Unified Test Format

• Status: Accepted
• Minimum Server Version: N/A
• Current Schema Version: 1.19.0

Abstract

This project defines a unified schema for YAML and JSON specification tests, which run operations against a MongoDB deployment. By conforming various spec tests to a single schema, drivers can implement a single test runner to execute acceptance tests for multiple specifications, thereby reducing maintenance of existing specs and implementation time for new specifications.

META

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

This document tends to use "SHOULD" more frequently than other specifications, but mainly in the context of providing guidance on writing test files. This is discussed in more detail in Design Rationale.

Goals

This test format can be used to define tests for the following specifications:

• Change Streams
• Command Logging and Monitoring
• CRUD
• GridFS
• Retryable Reads
• Retryable Writes
• Sessions
• Transactions
• Convenient API for Transactions
• Server Discovery and Monitoring

This is not an exhaustive list. Specifications that are known to not be supported by this format may be discussed under Future Work.

Specification

Terms

Entity Any object or value that is indexed by a unique name and stored in the Entity Map. This will typically be a driver object (e.g. client, session) defined in createEntities but may also be a saved operation result. A exhaustive list of supported types is presented in Supported Entity Types. Entities are referenced by name throughout the test file (e.g. Entity Test Operations).

Internal MongoClient A MongoClient created specifically for use with internal test operations, such as inserting collection data before a test, performing special assertions during a test, or asserting collection data after a test.

Iterable This term is used by various specifications as the return type for operations that return a sequence of items, which may be iterated. For example, the CRUD spec uses this as the return value for find and permit API flexibility rather than stipulate that a cursor object be returned directly.

Server Compatibility

The unified test format is intended to only run against enterprise servers. Additionally, many tests make use of Server Fail Points, so servers MUST be launched with the enableTestCommands parameter enabled.

Schema Version

This specification and the Test Format follow semantic versioning. The version is primarily used to validate test files with a JSON schema and also allow test runners to determine whether a particular test file is supported.

New tests files SHOULD always be written using the latest major version of this specification; however, test files SHOULD be conservative in the minor version they specify (as noted in schemaVersion).

JSON Schema Validation

Each major or minor version that changes the Test Format SHALL have a corresponding JSON schema. When a new schema file is introduced, any existing schema files MUST remain in place since they may be needed for validation. For example: if an additive change is made to version 1.0 of the spec, the schema-1.0.json file will be copied to schema-1.1.json and modified accordingly. A new or existing test file using schemaVersion "1.0" would then be expected to validate against both schema files. Schema version bumps MUST be noted in the Changelog.

A particular minor version MUST be capable of validating any and all test files in that major version series up to and including the minor version. For example, schema-2.1.json should validate test files with schemaVersion "2.0" and "2.1", but would not be expected to validate files specifying "1.0", "2.2", or "3.0".

The JSON schema MUST remain consistent with the Test Format section. If and when a new major version is introduced, the Breaking Changes section MUST be updated.

Ajv MAY be used to programmatically validate both YAML and JSON files using the JSON schema. The JSON schema MUST NOT use syntax that is unsupported by this tool, which bears mentioning because there are multiple versions of the JSON schema specification.

Test Runner Support

Each test file defines a schemaVersion, which test runners will use to determine compatibility (i.e. whether and how the test file will be interpreted). Test files are considered compatible with a test runner if their schemaVersion is less than or equal to a supported version in the test runner, given the same major version component. For example:

• A test runner supporting version 1.5.1 could execute test files with versions 1.0 and 1.5 but not 1.6 and 2.0.
• A test runner supporting version 2.1 could execute test files with versions 2.0 and 2.1 but not 1.0 and 1.5.
• A test runner supporting both versions 1.5.1 and 2.0 could execute test files with versions 1.4, 1.5, and 2.0, but not 1.6, 2.1, or 3.0.
• A test runner supporting version 2.0.1 could execute test files with versions 2.0 and 2.0.1 but not 2.0.2 or 2.1. This example is provided for completeness, but test files SHOULD NOT need to refer to patch versions (as previously mentioned).

Test runners MUST NOT process incompatible files and MUST raise an error if they encounter an incompatible file (as discussed in Executing a Test File). Test runners MAY support multiple schema versions (as demonstrated in the example above).

Impact of Spec Changes on Schema Version

Backwards-breaking changes SHALL warrant a new major version. These changes include, but are not limited to:

• Subtractive changes, such as removing a field, operation, or type of supported entity or event
• Changing an existing field from optional to required
• Introducing a new, required field in the test format
• Significant changes to test file execution (not BC)

Backwards-compatible changes SHALL warrant a new minor version. These changes include, but are not limited to:

• Additive changes, such as a introducing a new Special Test Operations or type of supported entity or event
• Changing an existing field from required to optional
• Introducing a new, optional field in the test format
• Minor changes to test file execution (BC)

Small fixes and internal spec changes (e.g. grammar, adding clarifying text to the spec) MAY warrant a new patch version; however, patch versions SHOULD NOT alter the structure of the test format and thus SHOULD NOT be relevant to test files (as noted in schemaVersion).

Entity Map

The entity map indexes arbitrary objects and values by unique names, so that they can be referenced from test constructs (e.g. operation.object). To ensure each test is executed in isolation, test runners MUST NOT share entity maps between tests. Most entities will be driver objects created by the createEntities directive during test setup, but the entity map may also be modified during test execution via the operation.saveResultAsEntity directive.

Test runners MAY choose to implement the entity map in a fashion most suited to their language, but implementations MUST enforce both uniqueness of entity names and referential integrity when fetching an entity. Test runners MUST raise an error if an attempt is made to store an entity with a name that already exists in the map and MUST raise an error if an entity is not found for a name or is found but has an unexpected type.

Test runners MUST provide a mechanism to retrieve entities from the entity map prior to the clearing of the entity map, as discussed in Executing a Test. There MUST be a way to retrieve an entity by its name (for example, to support retrieving the iteration count stored by the storeIterationsAsEntity option).

Test runners MAY restrict access to driver objects (e.g. MongoClient, ChangeStream) and only allow access to BSON types (see: Supported Entity Types). This restriction may be necessary if the test runner needs to ensure driver objects in its entity map are properly freed/destroyed between tests.

The entity map MUST be implemented in a way that allows for safe concurrent access, since a test may include multiple thread entities that all need to access the map concurrently. See entity_thread for more information on test runner threads.

Consider the following examples:

# Error due to a duplicate name (client0 was already defined)
createEntities:
  - client: { id: client0 }
  - client: { id: client0 }

# Error due to a missing entity (client1 is undefined)
createEntities:
  - client: { id: client0 }
  - session: { id: session0, client: client1 }

# Error due to an unexpected entity type (session instead of client)
createEntities:
  - client: { id: client0 }
  - session: { id: session0, client: client0 }
  - session: { id: session1, client: session0 }

Supported Entity Types

Test runners MUST support the following types of entities:

• MongoClient. See entity_client and Client Operations.
• ClientEncryption. See entity_clientEncryption and ClientEncryption Operations.
• Database. See entity_database and Database Operations.
• Collection. See entity_collection and Collection Operations
• ClientSession. See entity_session and Session Operations.
• GridFS Bucket. See entity_bucket and Bucket Operations.

• ChangeStream. Change stream entities are special in that they are not defined in createEntities but are instead created by using operation.saveResultAsEntity with a client_createChangeStream, database_createChangeStream, or collection_createChangeStream operation.

  Test files SHOULD NOT use a watch operation to create a change stream, as the implementation of that method may vary among drivers. For example, some implementations of watch immediately execute aggregate and construct the server-side cursor, while others may defer aggregate until the change stream object is iterated.

  See Cursor Operations for a list of operations.

• FindCursor. These entities are not defined in createEntities but are instead created by using operation.saveResultAsEntity with a collection_createFindCursor operation.

  See Cursor Operations for a list of operations.

• CommandCursor. These entities are not defined in createEntities but are instead created by using operation.saveResultAsEntity with a createCommandCursor operation.

  See Cursor Operations for a list of operations.

• Event list. See storeEventsAsEntities. The event list MUST store BSON documents. The type of the list itself is not prescribed by this specification. Test runner MAY use a BSON array or a thread-safe list data structure to implement the event list.

• All known BSON types and/or equivalent language types for the target driver. For the present version of the spec, the following BSON types are known: 0x01-0x13, 0x7F, 0xFF.

  Tests SHOULD NOT utilize deprecated types (e.g. 0x0E: Symbol), since they may not be supported by all drivers and could yield runtime errors (e.g. while loading a test file with an Extended JSON parser).

• Test runner thread. An entity representing a "thread" that can be used to concurrently execute operations. Thread entities MUST be able to run concurrently with the main test runner thread and other thread entities, but they do not have to be implemented as actual OS threads (e.g. they can be goroutines or async tasks). See entity_thread_object for more information on how they are created.

• TopologyDescription. An entity representing a client's TopologyDescription at a certain point in time. These entities are not defined in createEntities but are instead created via recordTopologyDescription test runner operations.

This is an exhaustive list of supported types for the entity map. Test runners MUST raise an error if an attempt is made to store an unsupported type in the entity map.

Adding new entity types (including known BSON types) to this list will require a minor version bump to the spec and schema version. Removing entity types will require a major version bump. See Impact of Spec Changes on Schema Version for more information.

Test Format

Each specification test file can define one or more tests, which inherit some top-level configuration (e.g. namespace, initial data). YAML and JSON test files are parsed as an object by the test runner. This section defines the top-level keys for that object and links to various sub-sections for definitions of nested structures (e.g. individual test, operation).

Although test runners are free to process YAML or JSON files, YAML is the canonical format for writing tests. YAML files may be converted to JSON using a tool such as js-yaml .

Top-level Fields

The top-level fields of a test file are as follows:

• description: Required string. The name of the test file.

  This SHOULD describe the common purpose of tests in this file and MAY refer to the filename (e.g. "updateOne-hint").

• schemaVersion: Required string. Version of this specification with which the test file complies.

  Test files SHOULD be conservative when specifying a schema version. For example, if the latest schema version is 1.1 but the test file complies with schema version 1.0, the test file should specify 1.0.

  Test runners will use this to determine compatibility (i.e. whether and how the test file will be interpreted). The format of this string is defined in Version String; however, test files SHOULD NOT need to refer to specific patch versions since patch-level changes SHOULD NOT alter the structure of the test format (as previously noted in Schema Version).

• runOnRequirements: Optional array of one or more runOnRequirement objects. List of server version and/or topology requirements for which the tests in this file can be run. If no requirements are met, the test runner MUST skip this test file.

• createEntities: Optional array of one or more entity objects. List of entities (e.g. client, collection, session objects) that SHALL be created before each test case is executed.

  Test files SHOULD define entities in dependency order, such that all referenced entities (e.g. client) are defined before any of their dependent entities (e.g. database, session).

• initialData: Optional array of one or more collectionData objects. Data that will exist in collections before each test case is executed.

• tests: Required array of one or more test objects. List of test cases to be executed independently of each other.
• _yamlAnchors: Optional object containing arbitrary data. This is only used to define anchors within the YAML files and MUST NOT be used by test runners.

runOnRequirement

A combination of server version and/or topology requirements for running the test(s).

The format of server version strings is defined in Version String. When comparing server version strings, each component SHALL be compared numerically. For example, "4.0.10" is greater than "4.0.9" and "3.6" and less than "4.2.0".

The structure of this object is as follows:

• minServerVersion: Optional string. The minimum server version (inclusive) required to successfully run the tests. If this field is omitted, there is no lower bound on the required server version. The format of this string is defined in Version String.

• maxServerVersion: Optional string. The maximum server version (inclusive) against which the tests can be run successfully. If this field is omitted, there is no upper bound on the required server version. The format of this string is defined in Version String.

• topologies: Optional array of one or more strings. Server topologies against which the tests can be run successfully. Valid topologies are "single", "replicaset", "sharded", "load-balanced", and "sharded-replicaset" (i.e. sharded cluster backed by replica sets). If this field is omitted, there is no topology requirement for the test.

  When matching a "sharded-replicaset" topology, test runners MUST ensure that all shards are backed by a replica set. The process for doing so is described in Determining if a Sharded Cluster Uses Replica Sets. When matching a "sharded" topology, test runners MUST accept any type of sharded cluster (i.e. "sharded" implies "sharded-replicaset", but not vice versa).

  The "sharded-replicaset" topology type is deprecated. MongoDB 3.6+ requires that all shard servers be replica sets. Therefore, tests SHOULD use "sharded" instead of "sharded-replicaset" when targeting 3.6+ server versions in order to avoid unnecessary overhead.

  Note: load balancers were introduced in MongoDB 5.0. Therefore, any sharded cluster behind a load balancer implicitly uses replica sets for its shards.

• serverless: Optional string. Whether or not the test should be run on Atlas Serverless instances. Valid values are "require", "forbid", and "allow". If "require", the test MUST only be run on Atlas Serverless instances. If "forbid", the test MUST NOT be run on Atlas Serverless instances. If omitted or "allow", this option has no effect.

  The test runner MUST be informed whether or not Atlas Serverless is being used in order to determine if this requirement is met (e.g. through an environment variable or configuration option).

  Note: the Atlas Serverless proxy imitates mongos, so the test runner is not capable of determining if Atlas Serverless is in use by issuing commands such as buildInfo or hello. Furthermore, connections to Atlas Serverless use a load balancer, so the topology will appear as "load-balanced".

• serverParameters: Optional object of server parameters to check against. To check server parameters, drivers send a { getParameter: 1, <parameter>: 1 } command to the server using an internal MongoClient. Drivers MAY also choose to send a { getParameter: '*' } command and fetch all parameters at once. The result SHOULD be cached to avoid repeated calls to fetch the same parameter. Test runners MUST apply the rules specified in Flexible Numeric Comparisons when comparing values. If a server does not support a parameter, test runners MUST treat the comparison as not equal and skip the test. This includes errors that occur when fetching a single parameter using getParameter.

• auth: Optional boolean. If true, the tests MUST only run if authentication is enabled. If false, tests MUST NOT run if authentication is enabled. If this field is omitted, there is no authentication requirement.

• authMechanism: Optional string. Specifies an authentication mechanism that the server needs to support for the test. If set, tests MUST only run if the given string matches (case-insensitive) one of the strings in the authenticationMechanisms server parameter. If this field is omitted, there is no authentication mechanism requirement.

• csfle: Optional boolean. If true, the tests MUST only run if the driver and server support Client-Side Field Level Encryption. CSFLE is supported when all of the following are true:

  • Server version is 4.2.0 or higher
  • Driver has libmongocrypt enabled
  • At least one of crypt_shared and/or mongocryptd is available

  If false, tests MUST NOT run if CSFLE is supported. If this field is omitted, there is no CSFLE requirement.

Test runners MAY evaluate these conditions in any order. For example, it may be more efficient to evaluate serverless or auth before communicating with a server to check its version.

entity

An entity (e.g. client, collection, session object) that will be created in the Entity Map before each test is executed.

This object MUST contain exactly one top-level key that identifies the entity type and maps to a nested object, which specifies a unique name for the entity (id key) and any other parameters necessary for its construction. Tests SHOULD use sequential names based on the entity type (e.g. "session0", "session1").

When defining an entity object in YAML, a node anchor SHOULD be created on the entity's id key. This anchor will allow the unique name to be referenced with an alias node later in the file (e.g. from another entity or operation object) and also leverage YAML's parser for reference validation.

The structure of this object is as follows:

• client: Optional object. Defines a MongoClient object. In addition to the configuration defined below, test runners for drivers that implement connection pooling MUST track the number of connections checked out at any given time for the constructed MongoClient. This can be done using a single counter and CMAP events. Each ConnectionCheckedOutEvent should increment the counter and each ConnectionCheckedInEvent should decrement it.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &client0 client0).

  • uriOptions: Optional object. Additional URI options to apply to the test suite's connection string that is used to create this client. Any keys in this object MUST override conflicting keys in the connection string.

    Documentation for supported options may be found in the URI Options spec, with one notable exception: if readPreferenceTags is specified in this object, the key will map to an array of strings, each representing a tag set, since it is not feasible to define multiple readPreferenceTags keys in the object.

    Note also that when specifying directConnection as true, the connection string used to instantiate a client MUST only have a single seed and MUST NOT specify the replicaSet option. See the URI Options spec for more information.

    Any field in uriOptions may be a $$placeholder document and the test runner MUST support replacing the placeholder document with values loaded from the test environment. For example:

    uriOptions:
      authMechanism: "MONGODB-OIDC"
      authMechanismProperties:
        ENVIRONMENT: { $$placeholder: 1 }
    

  • useMultipleMongoses: Optional boolean. If true and the topology is a sharded cluster, the test runner MUST assert that this MongoClient connects to multiple mongos hosts (e.g. by inspecting the connection string). If false and the topology is a sharded cluster, the test runner MUST ensure that this MongoClient connects to only a single mongos host (e.g. by modifying the connection string).

    If this option is not specified and the topology is a sharded cluster, the test runner MUST NOT enforce any limit on the number of mongos hosts in the connection string and any tests using this client SHOULD NOT depend on a particular number of mongos hosts.

    This option SHOULD be set to true in test files if the resulting entity is used to conduct transactions against a sharded cluster. This is advised because connecting to multiple mongos servers is necessary to test session pinning.

    If the topology type is LoadBalanced and Atlas Serverless is not being used, the test runner MUST use one of the two load balancer URIs described in Initializing the Test Runner to configure the MongoClient. If useMultipleMongoses is true or unset, the test runner MUST use the URI of the load balancer fronting multiple servers. Otherwise, the test runner MUST use the URI of the load balancer fronting a single server.

    If the topology type is LoadBalanced and Atlas Serverless is being used, this option has no effect. This is because provisioning an Atlas Serverless instance yields a single URI (i.e. a load balancer fronting a single Atlas Serverless proxy).

    This option has no effect for topologies that are not sharded or load balanced.

  • observeEvents: Optional array of one or more strings. Types of events that can be observed for this client. Unspecified event types MUST be ignored by this client's event listeners and SHOULD NOT be included in test.expectEvents for this client.

    Supported types correspond to the top-level keys (strings) documented in expectedEvent and are as follows:

    • commandStartedEvent
    • commandSucceededEvent
    • commandFailedEvent
    • poolCreatedEvent
    • poolReadyEvent
    • poolClearedEvent
    • poolClosedEvent
    • connectionCreatedEvent
    • connectionReadyEvent
    • connectionClosedEvent
    • connectionCheckOutStartedEvent
    • connectionCheckOutFailedEvent
    • connectionCheckedOutEvent
    • connectionCheckedInEvent
    • serverDescriptionChangedEvent
    • serverHeartbeatStartedEvent
    • serverHeartbeatSucceededEvent
    • serverHeartbeatFailedEvent
    • topologyDescriptionChangedEvent

  • ignoreCommandMonitoringEvents: Optional array of one or more strings. Command names for which the test runner MUST ignore any observed command monitoring events. The command(s) will be ignored in addition to configureFailPoint and any commands containing sensitive information (per the Command Logging and Monitoring spec) unless observeSensitiveCommands is true.

    Test files SHOULD NOT use this option unless one or more command monitoring events are specified in observeEvents.

  • observeSensitiveCommands: Optional boolean. If true, events associated with sensitive commands (per the Command Logging and Monitoring spec) will be observed for this client. Note that the command and replies for such events will already have been redacted by the driver. If false or not specified, events for commands containing sensitive information MUST be ignored. Authentication SHOULD be disabled when this property is true, i.e. auth should be false for each runOnRequirement. See rationale_observeSensitiveCommands.

  • storeEventsAsEntities: Optional array of one or more storeEventsAsEntity objects. Each object denotes an entity name and one or more events to be collected and stored in that entity. See storeEventsAsEntity for implementation details.

    Note: the implementation of storeEventsAsEntities is wholly independent from observeEvents and ignoreCommandMonitoringEvents.

    Example option value:

    storeEventsAsEntities:
      - id: client0_events
        events: [PoolCreatedEvent, ConnectionCreatedEvent, CommandStartedEvent]
    

  • observeLogMessages: Optional object where the key names are log components and the values are minimum log severity levels indicating which components to collect log messages for and what the minimum severity level of collected messages should be. Messages for unspecified components and/or with lower severity levels than those specified MUST be ignored by this client's log collector(s) and SHOULD NOT be included in test.expectLogMessages for this client.
  • serverApi: Optional serverApi object.

• clientEncryption: Optional object. Defines a ClientEncryption object.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &clientEncryption0 clientEncryption0).

  • clientEncryptionOpts: Required document. A value corresponding to a ClientEncryptionOpts.

    Note: the tlsOptions document is intentionally omitted from the test format. However, drivers MAY internally configure TLS options as needed to satisfy the requirements of configured KMS providers.

    The structure of this document is as follows:

    • keyVaultClient: Required string. Client entity from which this ClientEncryption will be created. The YAML file SHOULD use an alias node for a client entity's id field (e.g. client: *client0).

    • keyVaultNamespace: Required string. The database and collection to use as the key vault collection for this clientEncryption. The namespace takes the form database.collection (e.g. keyVaultNamespace: keyvault.datakeys).

    • kmsProviders: Required document. Drivers MUST NOT configure a KMS provider if it is not given. This is to permit testing conditions where a required KMS provider is not configured. If a KMS provider is given as an empty document (e.g. kmsProviders: { aws: {} }), drivers MUST configure the KMS provider without credentials to permit testing conditions where KMS credentials are needed. If a KMS credentials field has a placeholder value (e.g. kmsProviders: { aws: { accessKeyId: { $$placeholder: 1 }, secretAccessKey: { $$placeholder: 1 } } }), drivers MUST replace the field with credentials that satisfy the operations required by the unified test files. Drivers MAY load the credentials from the environment or a configuration file as needed to satisfy the requirements of the given KMS provider and tests. If a KMS credentials field is not given (e.g. the required field secretAccessKey is omitted in: kmsProviders: { aws: { accessKeyId: { $$placeholder: 1 } }), drivers MUST NOT include the field during KMS configuration. This is to permit testing conditions where required KMS credentials fields are not provided. Otherwise, drivers MUST configure the KMS provider with the explicit value of KMS credentials field given in the test file (e.g. kmsProviders: { aws: { accessKeyId: abc, secretAccessKey: def } }). This is to permit testing conditions where invalid KMS credentials are provided.

      Tests may also reference named KMS providers. KMS providers with the name name1 are expected to be configured exactly as the unnamed KMS providers. The aws:name2 KMS provider and aws:name1 KMS providers deliberately use separate AWS accounts that do not have permission to the other's keys.

      See the Client-Side Encryption test README for instructions to obtain test credentials.

• database: Optional object. Defines a Database object.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &database0 database0).
  • client: Required string. Client entity from which this database will be created. The YAML file SHOULD use an alias node for a client entity's id field (e.g. client: *client0).
  • databaseName: Required string. Database name. The YAML file SHOULD define a node anchor for this field (e.g. databaseName: &database0Name foo).
  • databaseOptions: Optional collectionOrDatabaseOptions object.

• collection: Optional object. Defines a Collection object.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &collection0 collection0).
  • database: Required string. Database entity from which this collection will be created. The YAML file SHOULD use an alias node for a database entity's id field (e.g. database: *database0).
  • collectionName: Required string. Collection name. The YAML file SHOULD define a node anchor for this field (e.g. collectionName: &collection0Name foo).
  • collectionOptions: Optional collectionOrDatabaseOptions object.

• session: Optional object. Defines an explicit ClientSession object.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &session0 session0).

  • client: Required string. Client entity from which this session will be created. The YAML file SHOULD use an alias node for a client entity's id field (e.g. client: *client0).

  • sessionOptions: Optional object. Map of parameters to pass to MongoClient.startSession when creating the session. Supported options are defined in the following specifications:

    • Causal Consistency
    • Snapshot Reads
    • Transactions
    • Client Side Operations Timeout

    When specifying TransactionOptions for defaultTransactionOptions, the transaction options MUST remain nested under defaultTransactionOptions and MUST NOT be flattened into sessionOptions.

• bucket: Optional object. Defines a Bucket object, as defined in the GridFS spec.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &bucket0 bucket0).
  • database: Required string. Database entity from which this bucket will be created. The YAML file SHOULD use an alias node for a database entity's id field (e.g. database: *database0).
  • bucketOptions: Optional object. Additional options used to construct the bucket object. Supported options are defined in the GridFS specification. The readConcern, readPreference, and writeConcern options use the same structure as defined in Common Options.

• thread: Optional object. Defines a test runner "thread". Once the "thread" has been created, it should be idle and waiting for operations to be dispatched to it later on by runOnThread operations.

  The structure of this object is as follows:

  • id: Required string. Unique name for this entity. The YAML file SHOULD define a node anchor for this field (e.g. id: &thread0 thread0).

storeEventsAsEntity

A list of one or more events that will be observed on a client and collectively stored within an entity. This object is used within storeEventsAsEntities.

The structure of this object is as follows:

• id: Required string. Unique name for this entity.
• events: Required array of one or more strings, which denote the events to be collected. Currently, only the following CMAP and command monitoring events MUST be supported:
  • PoolCreatedEvent
  • PoolReadyEvent
  • PoolClearedEvent
  • PoolClosedEvent
  • ConnectionCreatedEvent
  • ConnectionReadyEvent
  • ConnectionClosedEvent
  • ConnectionCheckOutStartedEvent
  • ConnectionCheckOutFailedEvent
  • ConnectionCheckedOutEvent
  • ConnectionCheckedInEvent
  • CommandStartedEvent
  • CommandSucceededEvent
  • CommandFailedEvent

For the specified entity name, the test runner MUST create the respective entity with a type of "event list", as described in Supported Entity Types. If the entity already exists (such as from a previous storeEventsAsEntity object) the test runner MUST raise an error.

The test runner MUST set up an event subscriber for each event named. The event subscriber MUST serialize the events it receives into a document, using the documented properties of the event as field names, and append the document to the list stored in the specified entity. Additionally, the following fields MUST be stored with each event document:

• name: The name of the event (e.g. PoolCreatedEvent). The name of the event MUST be the name used in the respective specification that defines the event in question.
• observedAt: The time, as the floating-point number of seconds since the Unix epoch, when the event was observed by the test runner.

The test runner MAY omit the command field for CommandStartedEvent and reply field for CommandSucceededEvent.

If an event field in the driver is of a type that does not directly map to a BSON type (e.g. Exception for the failure field of CommandFailedEvent) the test runner MUST convert values of that field to one of the BSON types. For example, a test runner MAY store the exception's error message string as the failure field of CommandFailedEvent.

If the specification defining an event permits deviation in field names, such as connectionId field for CommandStartedEvent, the test runner SHOULD use the field names used in the specification when serializing events to documents even if the respective field name is different in the driver's event object.

serverApi

Declares an API version for a client entity.

The structure of this object is as follows:

• version: Required string. Test runners MUST fail if the given version string is not supported by the driver.

  Note: the format of this string is unrelated to Version String.

• strict: Optional boolean.

• deprecationErrors: Optional boolean.

See the Stable API spec for more details on these fields.

collectionData

List of documents corresponding to the contents of a collection. This structure is used by both initialData and test.outcome, which insert and read documents, respectively.

The structure of this object is as follows:

• collectionName: Required string. See commonOptions_collectionName.
• databaseName: Required string. See commonOptions_databaseName.
• createOptions: Optional object. When used in initialData, these options MUST be passed to the create command when creating the collection. Test files MUST NOT specify writeConcern in this options document as that could conflict with the use of the majority write concern when the collection is created during test execution.
• documents: Required array of objects. List of documents corresponding to the contents of the collection. This list may be empty.

test

Test case consisting of a sequence of operations to be executed.

The structure of this object is as follows:

• description: Required string. The name of the test.

  This SHOULD describe the purpose of this test (e.g. "insertOne is retried").

• runOnRequirements: Optional array of one or more runOnRequirement objects. List of server version and/or topology requirements for which this test can be run. If specified, these requirements are evaluated independently and in addition to any top-level runOnRequirements. If no requirements in this array are met, the test runner MUST skip this test.

  These requirements SHOULD be more restrictive than those specified in the top-level runOnRequirements (if any) and SHOULD NOT be more permissive. This is advised because both sets of requirements MUST be satisfied in order for a test to be executed and more permissive requirements at the test-level could be taken out of context on their own.

• skipReason: Optional string. If set, the test will be skipped. The string SHOULD explain the reason for skipping the test (e.g. JIRA ticket).

• operations: Required array of operation objects. List of operations to be executed for the test case.

• expectEvents: Optional array of one or more expectedEventsForClient objects. For one or more clients, a list of events that are expected to be observed in a particular order.

  If a driver only supports configuring event listeners globally (for all clients), the test runner SHOULD associate each observed event with a client in order to perform these assertions.

  Tests SHOULD NOT specify multiple expectedEventsForClient objects for a single client entity with the same eventType field. For example, a test containing two expectedEventsForClient objects with the eventType set to cmap for both would either be redundant (if the events arrays were identical) or likely to fail (if the events arrays differed).

• expectLogMessages: Optional array of one or more expectedLogMessagesForClient objects. For one or more clients, a list of log messages that are expected to be observed in a particular order.

  If a driver only supports configuring log collectors globally (for all clients), the test runner SHOULD associate each observed message with a client in order to perform these assertions. One possible implementation is to add a test-only option to MongoClient which enables the client to store its entity name and add the entity name to each log message to enable filtering messages by client.

  Tests SHOULD NOT specify multiple expectedLogMessagesForClient objects for a single client entity.

• outcome: Optional array of one or more collectionData objects. Data that is expected to exist in collections after each test case is executed.

  The list of documents herein SHOULD be sorted ascendingly by the _id field to allow for deterministic comparisons. The procedure for asserting collection contents is discussed in Executing a Test.

operation

An operation to be executed as part of the test.

The structure of this object is as follows:

• name: Required string. Name of the operation (e.g. method) to perform on the object.

• object: Required string. Name of the object on which to perform the operation. This SHOULD correspond to either an entity name (for Entity Test Operations) or "testRunner" (for Special Test Operations). If the object is an entity, The YAML file SHOULD use an alias node for its id field (e.g. object: *collection0).

• arguments: Optional object. Map of parameter names and values for the operation. The structure of this object will vary based on the operation. See Entity Test Operations and Special Test Operations.

  The session parameter is handled specially (see commonOptions_session).

• ignoreResultAndError: Optional boolean. If true, both the error and result for the operation MUST be ignored.

  This field is mutually exclusive with expectResult, expectError, and saveResultAsEntity.

  This field SHOULD NOT be used for Special Test Operations (i.e. object: testRunner).

• expectError: Optional expectedError object. One or more assertions for an error expected to be raised by the operation.

  This field is mutually exclusive with expectResult and saveResultAsEntity.

  This field SHOULD NOT be used for Special Test Operations (i.e. object: testRunner).

• expectResult: Optional mixed type. A value corresponding to the expected result of the operation. This field may be a scalar value, a single document, or an array of values. Test runners MUST follow the rules in Evaluating Matches when processing this assertion.

  This field is mutually exclusive with expectError.

  This field SHOULD NOT be used for Special Test Operations (i.e. object: testRunner).

• saveResultAsEntity: Optional string. If specified, the actual result returned by the operation (if any) will be saved with this name in the Entity Map. The test runner MUST raise an error if the name is already in use or if the result does not comply with Supported Entity Types.

  This field is mutually exclusive with expectError.

  This field SHOULD NOT be used for Special Test Operations (i.e. object: testRunner).

expectedError

One or more assertions for an error/exception, which is expected to be raised by an executed operation. At least one key is required in this object.

The structure of this object is as follows:

• isError: Optional boolean. If true, the test runner MUST assert that an error was raised. This is primarily used when no other error assertions apply but the test still needs to assert an expected error. Test files MUST NOT specify false, as expectedError is only applicable when an operation is expected to raise an error.

• isClientError: Optional boolean. If true, the test runner MUST assert that the error originates from the client (i.e. it is not derived from a server response). If false, the test runner MUST assert that the error does not originate from the client.

  Client errors include, but are not limited to: parameter validation errors before a command is sent to the server; network errors.

• isTimeoutError: Optional boolean. If true, the test runner MUST assert that the error represents a timeout due to use of the timeoutMS option. If false, the test runner MUST assert that the error does not represent a timeout.

• errorContains: Optional string. A substring of the expected error message (e.g. "errmsg" field in a server error document). The test runner MUST assert that the error message contains this string using a case-insensitive match.

  See bulkWrite for special considerations for BulkWriteExceptions.

• errorCode: Optional integer. The expected "code" field in the server-generated error response. The test runner MUST assert that the error includes a server-generated response whose "code" field equals this value. In the interest of readability, YAML files SHOULD use a comment to note the corresponding code name (e.g. errorCode: 26 # NamespaceNotFound).

  Server error codes are defined in error_codes.yml.

  Test files SHOULD NOT assert error codes for client errors, as specifications do not define standardized codes for client errors.

• errorCodeName: Optional string. The expected "codeName" field in the server-generated error response. The test runner MUST assert that the error includes a server-generated response whose "codeName" field equals this value using a case-insensitive comparison.

  See bulkWrite for special considerations for BulkWriteExceptions.

  Server error codes are defined in error_codes.yml.

  Test files SHOULD NOT assert error codes for client errors, as specifications do not define standardized codes for client errors.

• errorLabelsContain: Optional array of one or more strings. A list of error label strings that the error is expected to have. The test runner MUST assert that the error contains all of the specified labels (e.g. using the hasErrorLabel method).

• errorLabelsOmit: Optional array of one or more strings. A list of error label strings that the error is expected not to have. The test runner MUST assert that the error does not contain any of the specified labels (e.g. using the hasErrorLabel method).

• writeErrors: Optional document. The write errors expected to be present in the error. The writeErrors document contains numeric keys representing the index of the write that failed and writeError object values. The test runner MUST assert that the error contains a writeError for each index present in writeErrors and MUST assert that the writeErrors match as root-level documents according to the rules in Evaluating Matches. The test runner MUST assert that the error does not contain any additional writeErrors. This field is only intended for use with the clientBulkWrite operation.

• writeConcernErrors: Optional array of one or more objects. An ordered list of write concern errors expected to be present in the error. The test runner MUST assert that each writeConcernError in this list matches the writeConcernError present at the same index in the error's list of writeConcernErrors as a root-level document according to the rules in Evaluating Matches. The test runner MUST assert that the error does not contain any additional writeConcernErrorss. This field is only intended for use with the clientBulkWrite operation.

• errorResponse: Optional document. A value corresponding to the expected server response. The test runner MUST assert that the error includes a server response that matches this value as a root-level document according to the rules in Evaluating Matches.

  Note that some drivers may not be able to evaluate errorResponse for write commands (i.e. insert, update, delete) and bulk write operations. For example, a BulkWriteException is derived from potentially multiple server responses and may not provide direct access to a single response. Tests SHOULD avoid using errorResponse for such operations if possible; otherwise, affected drivers SHOULD skip such tests if necessary.

• expectResult: Optional mixed type. This field follows the same rules as operation.expectResult and is only used in cases where the error includes a result (e.g. bulkWrite). If specified, the test runner MUST assert that the error includes a result and that it matches this value. If the result is optional (e.g. BulkWriteResult reported through the writeResult property of a BulkWriteException), this assertion SHOULD utilize the $$unsetOrMatches operator.

expectedEventsForClient

A list of events that are expected to be observed (in that order) for a client while executing operations.

The structure of each object is as follows:

• client: Required string. Client entity on which the events are expected to be observed. See commonOptions_client.
• eventType: Optional string. Specifies the type of the monitor which captured the events. Valid values are command for Command Monitoring events, cmap for CMAP events, and sdam for SDAM events. Defaults to command if omitted.
• events: Required array of expectedEvent objects. List of events, which are expected to be observed (in this order) on the corresponding client while executing operations. If the array is empty, the test runner MUST assert that no events were observed on the client (excluding ignored events).
• ignoreExtraEvents: Optional boolean. Specifies how the events array is matched against the observed events. If false, observed events after all specified events have matched MUST cause a test failure; if true, observed events after all specified events have been matched MUST NOT cause a test failure. Defaults to false.

expectedEvent

An event (e.g. APM), which is expected to be observed while executing the test's operations.

This object MUST contain exactly one top-level key that identifies the event type and maps to a nested object, which contains one or more assertions for the event's properties.

Some event properties are omitted in the following structures because they cannot be reliably tested. Taking command monitoring events as an example, requestId and operationId are nondeterministic and types for connectionId and failure can vary by implementation.

The events allowed in an expectedEvent object depend on the value of eventType in the corresponding expectedEventsForClient object, which can have one of the following values:

• command or omitted: only the event types defined in expectedCommandEvent are allowed.
• cmap: only the event types defined in expectedCmapEvent are allowed.
• sdam: only the event types defined in expectedSdamEvent are allowed.

expectedCommandEvent

The structure of this object is as follows:

• commandStartedEvent: Optional object. Assertions for one or more CommandStartedEvent fields.

  The structure of this object is as follows:

  • command: Optional document. A value corresponding to the expected command document. Test runners MUST follow the rules in Evaluating Matches when processing this assertion and match the value as a root-level document.
  • commandName: Optional string. Test runners MUST assert that the command name matches this value.
  • databaseName: Optional string. Test runners MUST assert that the database name matches this value. The YAML file SHOULD use an alias node for this value (e.g. databaseName: *database0Name).
  • hasServiceId: Defined in hasServiceId.
  • hasServerConnectionId: Defined in hasServerConnectionId.

• commandSucceededEvent: Optional object. Assertions for one or more CommandSucceededEvent fields.

  The structure of this object is as follows:

  • reply: Optional document. A value corresponding to the expected reply document. Test runners MUST follow the rules in Evaluating Matches when processing this assertion and match the value as a root-level document.
  • commandName: Optional string. Test runners MUST assert that the command name matches this value.
  • databaseName: Optional string. Test runners MUST assert that the database name matches this value. The YAML file SHOULD use an alias node for this value (e.g. databaseName: *database0Name).
  • hasServiceId: Defined in hasServiceId.
  • hasServerConnectionId: Defined in hasServerConnectionId.

• commandFailedEvent: Optional object. Assertions for one or more CommandFailedEvent fields.

  The structure of this object is as follows:

  • commandName: Optional string. Test runners MUST assert that the command name matches this value.
  • databaseName: Optional string. Test runners MUST assert that the database name matches this value. The YAML file SHOULD use an alias node for this value (e.g. databaseName: *database0Name).
  • hasServiceId: Defined in hasServiceId.
  • hasServerConnectionId: Defined in hasServerConnectionId.

expectedCmapEvent

• poolCreatedEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• poolReadyEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• poolClearedEvent: Optional object. Assertions for one or more PoolClearedEvent fields.

  The structure of this object is as follows:

  • hasServiceId: Defined in hasServiceId.
  • interruptInUseConnections: Optional boolean. If specified, test runners MUST assert that the field is set and matches this value.

• poolClosedEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• connectionCreatedEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• connectionReadyEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• connectionClosedEvent: Optional object. Assertions for one or more ConnectionClosedEvent fields.

  The structure of this object is as follows:

  • reason: Optional string. Test runners MUST assert that the reason in the published event matches this value. Valid values for this field are defined in the CMAP spec.

• connectionCheckOutStartedEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• connectionCheckOutFailedEvent: Optional object. Assertions for one or more ConnectionCheckOutFailedEvent fields.

  The structure of this object is as follows:

  • reason: Optional string. Test runners MUST assert that the reason in the published event matches this value. Valid values for this field are defined in the CMAP spec.

• connectionCheckedOutEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

• connectionCheckedInEvent: Optional object. If present, this object MUST be an empty document as all fields in this event are non-deterministic.

expectedSdamEvent

The structure of this object is as follows:

• serverDescriptionChangedEvent: Optional object. Assertions for one or more ServerDescriptionChangedEvent fields.

  The structure of this object is as follows:

  • previousDescription: Optional object. A value corresponding to the server description as it was before the change that triggered this event.
  • newDescription: Optional object. A value corresponding to the server description as it was after the change that triggered this event.

  The structure of a server description object (which the previousDescription and newDescription fields contain) is as follows:

  • type: Optional string. The type of the server in the description. Test runners MUST assert that the type in the published event matches this value. See SDAM: ServerType for a list of valid values.

• serverHeartbeatStartedEvent: Optional object. Assertions for one or more ServerHeartbeatStartedEvent fields.

  The structure of this object is as follows:

  • awaited: Optional boolean. If specified, test runners MUST assert that the field is set and matches this value.

• serverHeartbeatSucceededEvent: Optional object. Assertions for one or more ServerHeartbeatSucceededEvent fields.

  The structure of this object is as follows:

  • awaited: Optional boolean. If specified, test runners MUST assert that the field is set and matches this value.

• serverHeartbeatFailedEvent: Optional object. Assertions for one or more ServerHeartbeatFailedEvent fields.

  The structure of this object is as follows:

  • awaited: Optional boolean. If specified, test runners MUST assert that the field is set and matches this value.

• topologyDescriptionChangedEvent: Optional object. Assertions for one TopologyDescriptionChangedEvent object.

  The structure of this object is as follows:

  • previousDescription: Optional Object. A value corresponding to the topology description as it was before the change that triggered the event.

  • newDescription : Optional Object. A value corresponding to the topology description as it is after the change that triggered the event.

    Test runners SHOULD ignore any other fields than the previousDescription and newDescription fields.

    The structure of a topology description object (which the previousDescription and newDescription fields contain is as follows:

    • type: Optional string. The type of the topology in the description. Test runners MUST assert that the type in the published event matches this value. See SDAM: TopologyType for a list of valid values.

    Test runners SHOULD ignore any other fields present on the previousDescription and newDescription fields of the captured topologyDescriptionChangedEvent.

hasServiceId

This field is an optional boolean that specifies whether or not the serviceId field of an event is set. If true, test runners MUST assert that the field is set and is a non-empty BSON ObjectId (i.e. all bytes of the ObjectId are not 0). If false, test runners MUST assert that the field is not set or is an empty BSON ObjectId.

hasServerConnectionId

This field is an optional boolean that specifies whether or not the serverConnectionId field of an event is set. If true, test runners MUST assert that the field is set and is a positive Int32. If false, test runners MUST assert that the field is not set, or, if the driver uses a nonpositive Int32 value to indicate the field being unset, MUST assert that serverConnectionId is a nonpositive Int32.

expectedLogMessagesForClient

A list of log messages that are expected to be observed (in that order) for a client while executing operations.

The structure of each object is as follows:

• client: Required string. Client entity for which the messages are expected to be observed. See commonOptions_client.
• messages: Required array of expectedLogMessage objects. List of messages, which are expected to be observed (in this order) on the corresponding client while executing operations. If the array is empty, the test runner MUST assert that no messages were observed on the client. The driver MUST assert that the messages produced are an exact match, i.e. that the expected and actual message counts are the same and that there are no extra messages emitted by the client during the test run. Note: ignoreMessages and ignoreExtraMessages may exclude log messages from this evaluation.
• ignoreMessages: Optional array of expectedLogMessage objects. Unordered set of messages, which MUST be ignored on the corresponding client while executing operations. The test runner MUST exclude all log messages from observed messages that match any of the messages in ignoreMessages array before messages evaluation. Matching rules used to match messages in ignoreMessages are identical to match rules used for messages matching.
• ignoreExtraMessages: Optional boolean. Specifies how the messages array is matched against the observed logs. If false, observed logs after all specified logs have matched MUST cause a test failure; if true, observed logs after all specified logs have been matched MUST NOT cause a test failure. Defaults to false.

expectedLogMessage

A log message which is expected to be observed while executing the test's operations.

The structure of each object is as follows:

• level: Required string. This MUST be one of the level names listed in log severity levels. This specifies the expected level for the log message and corresponds to the level used for the message in the specification that defines it. Note that since not all drivers will necessarily support all log levels, some driver may need to map the specified level to the corresponding driver-supported level. Test runners MUST assert that the actual level matches this value.

• component: Required string. This MUST be one of the component names listed in components. This specifies the expected component for the log message. Note that since naming variations are permitted for components, some drivers may need to map this to a corresponding language-specific component name. Test runners MUST assert that the actual component matches this value.

• failureIsRedacted: Optional boolean. This field SHOULD only be specified when the log message data is expected to contain a failure value.

  When failureIsRedacted is present and its value is true, the test runner MUST assert that a failure is present and that the failure has been redacted according to the rules defined for error redaction in the command logging and monitoring specification.

  When false, the test runner MUST assert that a failure is present and that the failure has NOT been redacted.

  The exact form of these assertions and how thorough they are will vary based on the driver's chosen error representation in logs; e.g. drivers that use strings may only be able to assert on the presence/absence of substrings.

• data: Required object. Contains key-value pairs that are expected to be attached to the log message. Test runners MUST assert that the actual data contained in the log message matches the expected data, and MUST treat the log message data as a root-level document.

  A suggested implementation approach is to decode data as a BSON document and serialize the data attached to each log message to a BSON document, and match those documents.

  Note that for drivers that do not implement structured logging, this requires designing logging internals such that data is first gathered in a structured form (e.g. a document or hashmap) which can be intercepted for testing purposes.

collectionOrDatabaseOptions

Map of parameters used to construct a collection or database object.

The structure of this object is as follows:

• readConcern: Optional object. See commonOptions_readConcern.
• readPreference: Optional object. See commonOptions_readPreference.
• writeConcern: Optional object. See commonOptions_writeConcern.

Common Options

This section defines the structure of common options that are referenced from various contexts in the test format. Comprehensive documentation for some of these types and their parameters may be found in the following specifications:

• Read and Write Concern.
• Server Selection: Read Preference.
• Server Discovery and Monitoring: TopologyDescription.

The structure of these common options is as follows:

• collectionName: String. Collection name. The YAML file SHOULD use an alias node for a collection entity's collectionName field (e.g. collectionName: *collection0Name).

• databaseName: String. Database name. The YAML file SHOULD use an alias node for a database entity's databaseName field (e.g. databaseName: *database0Name).

• readConcern: Object. Map of parameters to construct a read concern.

  The structure of this object is as follows:

  • level: Required string.

• readPreference: Object. Map of parameters to construct a read preference.

  The structure of this object is as follows:

  • mode: Required string.
  • tagSets: Optional array of objects.
  • maxStalenessSeconds: Optional integer.
  • hedge: Optional object.

• client: String. Client entity name, which the test runner MUST resolve to a MongoClient object. The YAML file SHOULD use an alias node for a client entity's id field (e.g. client: *client0).

• session: String. Session entity name, which the test runner MUST resolve to a ClientSession object. The YAML file SHOULD use an alias node for a session entity's id field (e.g. session: *session0).

• writeConcern: Object. Map of parameters to construct a write concern.

  The structure of this object is as follows:

  • journal: Optional boolean.
  • w: Optional integer or string.
  • wtimeoutMS: Optional integer.

Version String

Version strings, which are used for schemaVersion and runOnRequirement, MUST conform to one of the following formats, where each component is a non-negative integer:

• <major>.<minor>.<patch>
• <major>.<minor> (<patch> is assumed to be zero)
• <major> (<minor> and <patch> are assumed to be zero)

Any component other than major, minor, and patch MUST be discarded prior to comparing versions. This is necessary to ensure that spec tests run on pre-release versions of the MongoDB server. As an example, when checking if a server with the version 4.9.0-alpha4-271-g7d5cf02 passes the requirement for a test, only 4.9.0 is relevant for the comparison. When reading the server version from the buildInfo command reply, the three elements of the versionArray field MUST be used, and all other fields MUST be discarded for this comparison.

Entity Test Operations

Entity operations correspond to an API method on a driver object. If operation.object refers to an entity name (e.g. "collection0") then operation.name is expected to reference an API method on that class.

Test files SHALL use camelCase when referring to API methods and parameters, even if the defining specifications use other forms (e.g. snake_case in GridFS). Test files SHOULD use the exact API method names defined in specifications for entity test operations. Test files MAY use a different descriptive name if a naming conflict occurs. For example, the name "clientBulkWrite" is used for the client-level bulk write operation to differentiate it from the collection-level bulk write operation.

This spec does not provide exhaustive documentation for all possible API methods that may appear in a test; however, the following sections discuss all supported entities and their operations in some level of detail. Special handling for certain operations is also discussed as needed.

Expressing Required and Optional Parameters

Some specifications group optional parameters for API methods under an options parameter (e.g. options: Optional<UpdateOptions> in the CRUD spec); however, driver APIs vary in how they accept options (e.g. Python's keyword/named arguments, session as either an option or required parameter depending on whether a language supports method overloading). Therefore, test files SHALL declare all required and optional parameters for an API method directly within operation.arguments (e.g. upsert for updateOne is not nested under an options key).

Special Handling for Arguments

If session is specified in operation.arguments, it is defined according to commonOptions_session. Test runners MUST resolve the session argument to session entity before passing it as a parameter to any API method.

If readConcern, readPreference, or writeConcern are specified in operation.arguments, test runners MUST interpret them according to the corresponding definition in Common Options and MUST convert the value into the appropriate object before passing it as a parameter to any API method.

Converting Returned Model Objects to Documents

For operations that return a model object (e.g. BulkWriteResult for bulkWrite), the test runner MUST convert the model object to a document when evaluating expectResult or saveResultAsEntity. Similarly, for operations that may return iterables of model objects (e.g. DatabaseInfo for listDatabases), the test runner MUST convert the iterable to an array of documents when evaluating expectResult or saveResultAsEntity.

Iterating Returned Iterables

Unless otherwise stated by an operation below, test runners MUST fully iterate any iterable returned by an operation as part of that operation's execution. This is necessary to ensure consistent behavior among drivers, as discussed in collection_aggregate and find, and also ensures that error and event assertions can be evaluated consistently.

Client Operations

These operations and their arguments may be documented in the following specifications:

• Change Streams
• Enumerating Databases

Client operations that require special handling or are not documented by an existing specification are described below.

close

Closes the client, i.e. close underlying connection pool(s) and cease monitoring the topology. For languages that rely on built-in language mechanisms such as reference counting to automatically close/deinitialize clients once they go out of scope, this may require implementing an abstraction to allow a client entity's underlying client to be set to null. Because drivers do not consistently propagate errors encountered while closing a client, test files SHOULD NOT specify expectResult or expectError for this operation. Test files SHOULD NOT specify any operations for a client entity or any entity descended from it following a close operation on it, as driver behavior when an operation is attempted on a closed client or one of its descendant objects is not consistent.

createChangeStream

Creates a cluster-level change stream and ensures that the server-side cursor has been created.

This operation proxies the client's watch method and supports the same arguments and options. Test files SHOULD NOT use the client's watch operation directly for reasons discussed in ChangeStream. Test runners MUST ensure that the server-side cursor is created (i.e. aggregate is executed) as part of this operation and before the resulting change stream might be saved with operation.saveResultAsEntity.

Test runners MUST NOT iterate the change stream when executing this operation and test files SHOULD NOT specify operation.expectResult for this operation.

clientBulkWrite

These considerations only apply to the MongoClient.bulkWrite method. See bulkWrite for special considerations for MongoCollection.bulkWrite.

The models parameter for clientBulkWrite is documented as a list of WriteModel interfaces. Each WriteModel implementation (e.g. InsertOneModel) provides important context to the method, but that type information is not easily expressed in YAML and JSON. To account for this, test files MUST nest each WriteModel object in a single-key object, where the key identifies the request type (e.g. "insertOne") and its value is an object expressing the parameters, as in the following example:

arguments:
  models:
    - insertOne:
        document: { _id: 1, x: 1 }
    - replaceOne:
        filter: { _id: 2 }
        replacement: { x: 2 }
        upsert: true
    - updateOne:
        filter: { _id: 3 }
        update: { $set: { x: 3 } }
        upsert: true
    - updateMany:
        filter: { }
        update: { $inc: { x: 1 } }
    - deleteOne:
        filter: { x: 2 }
    - deleteMany:
        filter: { x: { $gt: 2 } }
  ordered: true

Because the insertResults, updateResults, and deleteResults may be absent or empty in the BulkWriteResult returned from a summary-only bulk write, the clientBulkWrite operation SHOULD use the $$unsetOrMatches operator for assertions on these fields when verboseResults is not set to true. This also applies to result objects defined in the expectedResult field of expectedError.

The BulkWriteException thrown by MongoClient.bulkWrite contains an optional error field that stores a top-level error that occurred during the bulk write. Test runners MUST inspect the contents of this field when making assertions based on the contents of the errorCode and errorContains fields in expectedError.

BulkWriteException also contains writeErrors and writeConcernErrors fields that define the individual write errors and write concern errors that occurred during the bulk write. Unified tests SHOULD use writeErrors and writeConcernErrors in expectedError to assert on the contents of these fields. Test runners MUST NOT inspect the contents of these fields when making assertions based on any other fields defined in expectedError.

While operations typically raise an error or return a result, the MongoClient.bulkWrite operation may report both via the partialResult property of a BulkWriteException. In this case, the intermediary write result may be matched with expectedError_expectResult

watch

This operation SHOULD NOT be used in test files. See client_createChangeStream.

ClientEncryption Operations

These operations and their arguments may be documented in the following specifications:

• Client Side Encryption

Operations that require sending and receiving KMS requests to encrypt or decrypt data keys may require appropriate KMS credentials to be loaded by the driver. Drivers MUST load appropriate KMS credentials (i.e. from the environment or a configuration file) when prompted by a test providing a placeholder value in a corresponding kmsProviders field as described under entity.clientEncryption.

See the Client-Side Encryption test README for instructions to obtain test credentials.

Drivers MUST be running the mock KMS KMIP server when evaluating tests that require KMS requests to a KMIP KMS provider.

Drivers MAY enforce a unique index on keyAltNames as described in the Client Side Field Level Encryption spec when running key management operations on the key vault collection. Although unified tests are written assuming the existence of the unique index, no unified test currently requires its implementation for correctness (e.g. no unified test currently attempts to create a data key with an existing keyAltName or add an existing keyAltName to a data key).

Database Operations

These operations and their arguments may be documented in the following specifications:

• Change Streams
• CRUD
• Enumerating Collections

Database operations that require special handling or are not documented by an existing specification are described below.

aggregate

When executing an aggregate operation, the test runner MUST fully iterate the result. This will ensure consistent behavior between drivers that eagerly create a server-side cursor and those that do so lazily when iteration begins.

createChangeStream

Creates a database-level change stream and ensures that the server-side cursor has been created.

This operation proxies the database's watch method and supports the same arguments and options. Test files SHOULD NOT use the database's watch operation directly for reasons discussed in ChangeStream. Test runners MUST ensure that the server-side cursor is created (i.e. aggregate is executed) as part of this operation and before the resulting change stream might be saved with operation.saveResultAsEntity.

Test runners MUST NOT iterate the change stream when executing this operation and test files SHOULD NOT specify operation.expectResult for this operation.

listCollections

When executing a listCollections operation, the test runner MUST fully iterate the resulting cursor.

runCommand

Generic command runner.

This method does not inherit a read preference (per the Server Selection spec); however, readPreference may be specified as an argument.

The following arguments are supported:

• command: Required document. The command to be executed.
• commandName: Required string. The name of the command to run. This is used by languages that are unable preserve the order of keys in the command argument when parsing YAML/JSON.
• readPreference: Optional object. See commonOptions_readPreference.
• session: Optional string. See commonOptions_session.

runCursorCommand

Generic cursor returning command runner.

This method does not inherit a read preference (per the Server Selection spec); however, readPreference may be specified as an argument.

This operation proxies the database's runCursorCommand method and supports the same arguments and options (note: handling for getMore options may vary by driver implementation).

When executing the provided command, the test runner MUST fully iterate the cursor. This will ensure consistent behavior between drivers that eagerly create a server-side cursor and those that do so lazily when iteration begins.

The following arguments are supported:

• command: Required document. The command to be executed.
• commandName: Required string. The name of the command to run. This is used by languages that are unable preserve the order of keys in the command argument when parsing YAML/JSON.
• readPreference: Optional object. See commonOptions_readPreference.
• session: Optional string. See commonOptions_session.
• batchSize: Optional positive integer value. Use this value to configure the batchSize option sent on subsequent getMore commands.
• maxTimeMS: Optional non-negative integer value. Use this value to configure the maxTimeMS option sent on subsequent getMore commands.
• comment: Optional BSON value. Use this value to configure the comment option sent on subsequent getMore commands.
• cursorType: Optional string enum value, one of 'tailable' | 'tailableAwait' | 'nonTailable'. Use this value to configure the enum passed to the cursorType option.
• timeoutMode: Optional string enum value, one of 'iteration' | 'cursorLifetime'. Use this value to configure the enum passed to the timeoutMode option.

createCommandCursor

This operation proxies the database's runCursorCommand method and supports the same arguments and options (note: handling for getMore options may vary by driver implementation). Test runners MUST ensure that the server-side cursor is created (i.e. the command document has executed) as part of this operation and before the resulting cursor might be saved with operation.saveResultAsEntity. Test runners for drivers that lazily execute the command on the first iteration of the cursor MUST iterate the resulting cursor once. The result from this iteration MUST be used as the result for the first iteration operation on the cursor.

Test runners MUST NOT iterate the resulting cursor when executing this operation and test files SHOULD NOT specify operation.expectResult for this operation.

watch

This operation SHOULD NOT be used in test files. See database_createChangeStream.

Collection Operations

These operations and their arguments may be documented in the following specifications:

• Change Streams
• CRUD
• Index Management

Collection operations that require special handling or are not documented by an existing specification are described below.

aggregate

When executing an aggregate operation, the test runner MUST fully iterate the result. This will ensure consistent behavior between drivers that eagerly create a server-side cursor and those that do so lazily when iteration begins.

When evaluating the iterated result for expectResult, the number of actual and expected documents MUST be equal and each document value within the expectResult array MUST be matched as a root-level document (for Evaluating Matches).

bulkWrite

These considerations only apply to the MongoCollection.bulkWrite method. See clientBulkWrite for special considerations for MongoClient.bulkWrite.

The requests parameter for bulkWrite is documented as a list of WriteModel interfaces. Each WriteModel implementation (e.g. InsertOneModel) provides important context to the method, but that type information is not easily expressed in YAML and JSON. To account for this, test files MUST nest each WriteModel object in a single-key object, where the key identifies the request type (e.g. "insertOne") and its value is an object expressing the parameters, as in the following example:

arguments:
  requests:
    - insertOne:
        document: { _id: 1, x: 1 }
    - replaceOne:
        filter: { _id: 2 }
        replacement: { x: 2 }
        upsert: true
    - updateOne:
        filter: { _id: 3 }
        update: { $set: { x: 3 } }
        upsert: true
    - updateMany:
        filter: { }
        update: { $inc: { x: 1 } }
    - deleteOne:
        filter: { x: 2 }
    - deleteMany:
        filter: { x: { $gt: 2 } }
  ordered: true

Because the insertedIds field of BulkWriteResult is optional for drivers to implement, assertions for that field SHOULD utilize the $$unsetOrMatches operator.

While operations typically raise an error or return a result, the bulkWrite operation is unique in that it may report both via the writeResult property of a BulkWriteException. In this case, the intermediary write result may be matched with expectedError_expectResult. Because writeResult is optional for drivers to implement, such assertions SHOULD utilize the $$unsetOrMatches operator.

Additionally, BulkWriteException is unique in that it aggregates one or more server errors in its writeConcernError and writeErrors properties. When test runners evaluate expectedError assertions for errorContains and errorCodeName, they MUST examine the aggregated errors and consider any match therein to satisfy the assertion(s). Drivers that concatenate all write and write concern error messages into the BulkWriteException message MAY optimize the check for errorContains by examining the concatenated message. Drivers that expose code but not codeName through BulkWriteException MAY translate the expected code name to a number (see: error_codes.yml) and compare with code instead, but MUST raise an error if the comparison cannot be attempted (e.g. code is also not available, translation fails).

createChangeStream

Creates a collection-level change stream and ensures that the server-side cursor has been created.

This operation proxies the collection's watch method and supports the same arguments and options. Test files SHOULD NOT use the collection's watch operation directly for reasons discussed in ChangeStream. Test runners MUST ensure that the server-side cursor is created (i.e. aggregate is executed) as part of this operation and before the resulting change stream might be saved with operation.saveResultAsEntity.

Test runners MUST NOT iterate the change stream when executing this operation and test files SHOULD NOT specify operation.expectResult for this operation.

createFindCursor

This operation proxies the collection's find method and supports the same arguments and options. Test runners MUST ensure that the server-side cursor is created (i.e. a find command is executed) as part of this operation and before the resulting cursor might be saved with operation.saveResultAsEntity. Test runners for drivers that lazily execute the find command on the first iteration of the cursor MUST iterate the resulting cursor once. The result from this iteration MUST be used as the result for the first iteration operation on the cursor.

Test runners MUST NOT iterate the resulting cursor when executing this operation and test files SHOULD NOT specify operation.expectResult for this operation.

createSearchIndex

This operations proxies the collection's createSearchIndex helper with the same arguments.

Each createSearchIndex operation receives a SearchIndexModel. If a driver has chosen to implement the createSearchIndex(name: String, definition: Document) overload of createSearchIndex, then the SearchIndexModel should be parsed by createSearchIndex unified test runner helper and the correct arguments should be passed into the driver's helper.

createSearchIndexes

This operations proxies the collection's createSearchIndexes helper with the same arguments.

dropSearchIndex

This operation proxies the collection's dropSearchIndex helper with the same arguments.

find

When executing a find operation, the test runner MUST fully iterate the result. This will ensure consistent behavior between drivers that eagerly create a server-side cursor and those that do so lazily when iteration begins.

When evaluating the iterated result for expectResult, the number of actual and expected documents MUST be equal and each document value within the expectResult array MUST be matched as a root-level document (for Evaluating Matches).

findOneAndReplace and findOneAndUpdate

The returnDocument option for findOneAndReplace and findOneAndUpdate is documented as an enum with possible values "Before" and "After". Test files SHOULD express returnDocument as a string and test runners MUST raise an error if its value does not case-insensitively match either enum value.

When evaluating the result for expectResult, the document MUST be matched as a root-level document (for Evaluating Matches).

insertMany

The CRUD spec documents insertMany as returning a BulkWriteResult. Because the insertedIds field of BulkWriteResult is optional for drivers to implement, assertions for that field SHOULD utilize the $$unsetOrMatches operator.

insertOne

The CRUD spec documents insertOne as returning an InsertOneResult; however, because all fields InsertOneResult are optional drivers are permitted to forgo it entirely and have insertOne return nothing (i.e. void method). Tests asserting InsertOneResult SHOULD utilize the $$unsetOrMatches operator for both the result object and any optional fields within, as in the following examples:

- name: insertOne
  object: *collection0
  arguments:
    document: { _id: 2 }
  expectResult:
    $$unsetOrMatches:
      insertedId: { $$unsetOrMatches: 2 }

listSearchIndexes

This operation proxies the collection's listSearchIndexes helper and returns the result of the cursor as a list.

updateSearchIndex

This operation proxies the collection's updateSearchIndex helper with the same arguments.

watch

This operation SHOULD NOT be used in test files. See collection_createChangeStream.

Session Operations

These operations and their arguments may be documented in the following specifications:

• Convenient API for Transactions
• Driver Sessions

Session operations that require special handling or are not documented by an existing specification are described below.

withTransaction

The withTransaction operation's callback parameter is a function and not easily expressed in YAML/JSON. For ease of testing, this parameter is expressed as an array of operation objects (analogous to test.operations). Test runners MUST evaluate error and result assertions when executing these operations in the callback.

Test runners MUST allow any errors from the callback operation(s) to propagate to withTransaction, irrespective of ignoreResultAndError or expectError. For example, if a callback operation raises an error, it should be possible to assert that error at both the callback operation and withTransaction level.

Bucket Operations

These operations and their arguments may be documented in the following specifications:

• GridFS

Bucket operations that require special handling or are not documented by an existing specification are described below.

download and downloadByName

These operations proxy the bucket's openDownloadStream and openDownloadStreamByName methods and support the same parameters and options, but return a string containing the stream's contents instead of the stream itself. Test runners MUST fully read the stream to yield the returned string. This is also necessary to ensure that any expected errors are raised (e.g. missing chunks). Test files SHOULD use $$matchesHexBytes in expectResult to assert the contents of the returned string.

downloadToStream and downloadToStreamByName

These operations SHOULD NOT be used in test files. See IO operations for GridFS streams in Future Work.

openDownloadStream and openDownloadStreamByName

These operations SHOULD NOT be used in test files. See download and downloadByName.

openUploadStream and openUploadStreamWithId

These operations SHOULD NOT be used in test files. See IO operations for GridFS streams in Future Work.

upload and uploadWithId

These operations proxy the bucket's uploadFromStream and uploadFromStreamWithId methods and support the same parameters and options with one exception: the source parameter is an object specifying hex bytes from which test runners MUST construct a readable stream for the underlying methods. The structure of source is as follows:

{ $$hexBytes: <string> }

The string MUST contain an even number of hexadecimal characters (case-insensitive) and MAY be empty. The test runner MUST raise an error if the structure of source or its string is malformed. The test runner MUST convert the string to a byte sequence denoting the stream's readable data (if any). For example, "12ab" would denote a stream with two bytes: "0x12" and "0xab".

uploadFromStream and uploadFromStreamWithId

These operations SHOULD NOT be used in test files. See upload and uploadWithId.

Cursor Operations

There are no defined APIs for change streams and cursors since the mechanisms for iteration may differ between synchronous and asynchronous drivers. To account for this, this section explicitly defines the supported operations for the ChangeStream, FindCursor, and CommandCursor entity types.

Test runners MUST ensure that the iteration operations defined in this section will not inadvertently skip the first document for a cursor. Albeit rare, this could happen if an operation were to blindly invoke next (or equivalent) on a cursor in a driver where newly created cursors are already positioned at their first element and the cursor had a non-empty firstBatch. Alternatively, some drivers may use a different iterator method for advancing a cursor to its first position (e.g. rewind in PHP).

iterateUntilDocumentOrError

Iterates the cursor until either a single document is returned or an error is raised. This operation takes no arguments. If expectResult is specified, it SHOULD be a single document and MUST be matched as a root-level document according to the rules in Evaluating Matches.

Some specification sections (e.g. Iterating the Change Stream) caution drivers that implement a blocking mode of iteration (e.g. asynchronous drivers) not to iterate the cursor unnecessarily, as doing so could cause the test runner to block indefinitely. This should not be a concern for iterateUntilDocumentOrError as iteration only continues until either a document or error is encountered.

iterateOnce

Performs a single iteration of the cursor. If the cursor's current batch is empty, one getMore MUST be attempted to get more results. This operation takes no arguments. If expectResult is specified, it SHOULD be a single document.

Due to the non-deterministic nature of some cursor types (e.g. change streams on sharded clusters), test files SHOULD only use this operation to perform command monitoring assertions on the getMore command. Tests that perform assertions about the result of iteration should use iterateUntilDocumentOrError instead.

close

Closes the cursor. Because drivers do not consistently propagate errors from the killCursors command, test runners MUST suppress all errors when closing the cursor. Test files SHOULD NOT specify expectResult or expectError for this operation. To assert whether the killCursors command succeeded or failed, test files SHOULD use command monitoring assertions with commandSucceededEvent and commandFailedEvent events.

Special Test Operations

Certain operations do not correspond to API methods but instead represent special test operations (e.g. assertions). These operations are distinguished by operation.object having a value of "testRunner". The operation.name field will correspond to an operation defined below.

Special test operations return no result and are always expected to succeed. These operations SHOULD NOT be combined with expectError, expectResult, or saveResultAsEntity.

failPoint

The failPoint operation instructs the test runner to configure a fail point using a "primary" read preference using the specified client entity (fail points are not configured using an internal MongoClient).

The following arguments are supported:

• failPoint: Required document. The configureFailPoint command to be executed.

• client: Required string. See commonOptions_client.

  The client entity SHOULD specify false for useMultipleMongoses if this operation could be executed on a sharded topology (according to runOnRequirements or test.runOnRequirements). This is advised because server selection rules for mongos could lead to unpredictable behavior if different servers were selected for configuring the fail point and executing subsequent operations.

When executing this operation, the test runner MUST keep a record of the fail point so that it can be disabled after the test. The test runner MUST also ensure that the configureFailPoint command is excluded from the list of observed command monitoring events for this client (if applicable).

An example of this operation follows:

# Enable the fail point on the server selected with a primary read preference
- name: failPoint
  object: testRunner
  arguments:
    client: *client0
    failPoint:
      configureFailPoint: failCommand
      mode: { times: 1 }
      data:
        failCommands: ["insert"]
        closeConnection: true

targetedFailPoint

The targetedFailPoint operation instructs the test runner to configure a fail point on a specific mongos.

The following arguments are supported:

• failPoint: Required document. The configureFailPoint command to be executed.

• session: Required string. See commonOptions_session.

  The client entity associated with this session SHOULD specify true for useMultipleMongoses. This is advised because targeted fail points are intended to test mongos pinning, which warrants multiple mongoses.

The mongos on which to set the fail point is determined by the session argument (after resolution to a session entity). Test runners MUST error if the session is not pinned to a mongos server at the time this operation is executed.

If the driver exposes an API to target a specific server for a command, the test runner SHOULD use the client entity associated with the session to execute the configureFailPoint command. In this case, the test runner MUST also ensure that this command is excluded from the list of observed command monitoring events for this client (if applicable). If such an API is not available, but the test runner creates an internal MongoClient for each mongos, the test runner SHOULD use the internal MongoClient corresponding to the session's pinned server for this operation. Otherwise, test runners MUST create a new MongoClient that is directly connected to the session's pinned server for this operation. The new MongoClient instance MUST be closed once the command has finished executing.

A test utilizing targetedFailPoint SHOULD NOT be permitted execute on a load balancer (according to runOnRequirements or test.runOnRequirements). This is advised because the configureFailPoint command does not use the session directly, which means there is no guarantee that the load balancer will direct the command to the intended mongos.

When executing this operation, the test runner MUST keep a record of both the fail point and pinned mongos server so that the fail point can be disabled on the same mongos server after the test.

An example of this operation follows:

# Enable the fail point on the mongos to which session0 is pinned
- name: targetedFailPoint
  object: testRunner
  arguments:
    session: *session0
    failPoint:
      configureFailPoint: failCommand
      mode: { times: 1 }
      data:
        failCommands: ["commitTransaction"]
        closeConnection: true

Since mongos pinning only applies when multiple mongoses are used, tests SHOULD NOT use targetedFailPoint unless the session's MongoClient is configured with useMultipleMongoses: true.

assertSessionTransactionState

The assertSessionTransactionState operation instructs the test runner to assert that the given session has a particular transaction state.

The following arguments are supported:

• session: Required string. See commonOptions_session.
• state: Required string. Expected transaction state for the session. Possible values are as follows: none, starting, in_progress, committed, and aborted.

An example of this operation follows:

- name: assertSessionTransactionState
  object: testRunner
  arguments:
    session: *session0
    state: in_progress

assertSessionPinned

The assertSessionPinned operation instructs the test runner to assert that the given session is pinned to a mongos server.

The following arguments are supported:

• session: Required string. See commonOptions_session.

An example of this operation follows:

- name: assertSessionPinned
  object: testRunner
  arguments:
    session: *session0

assertSessionUnpinned

The assertSessionUnpinned operation instructs the test runner to assert that the given session is not pinned to a mongos server.

The following arguments are supported:

• session: Required string. See commonOptions_session.

An example of this operation follows:

- name: assertSessionUnpinned
  object: testRunner
  arguments:
    session: *session0

assertDifferentLsidOnLastTwoCommands

The assertDifferentLsidOnLastTwoCommands operation instructs the test runner to assert that the last two CommandStartedEvents observed on the client have different lsid fields. This assertion is primarily used to test that dirty server sessions are discarded from the pool.

The following arguments are supported:

• client: Required string. See commonOptions_client.

  The client entity SHOULD include "commandStartedEvent" in observeEvents.

The test runner MUST fail this assertion if fewer than two CommandStartedEvents have been observed on the client or if either command does not include an lsid field.

An example of this operation follows:

- name: assertDifferentLsidOnLastTwoCommands
  object: testRunner
  arguments:
    client: *client0

assertSameLsidOnLastTwoCommands

The assertSameLsidOnLastTwoCommands operation instructs the test runner to assert that the last two CommandStartedEvents observed on the client have identical lsid fields. This assertion is primarily used to test that non-dirty server sessions are not discarded from the pool.

The following arguments are supported:

• client: Required string. See commonOptions_client.

  The client entity SHOULD include "commandStartedEvent" in observeEvents.

The test runner MUST fail this assertion if fewer than two CommandStartedEvents have been observed on the client or if either command does not include an lsid field.

An example of this operation follows:

- name: assertSameLsidOnLastTwoCommands
  object: testRunner
  arguments:
    client: *client0

assertSessionDirty

The assertSessionDirty operation instructs the test runner to assert that the given session is marked dirty.

The following arguments are supported:

• session: Required string. See commonOptions_session.

An example of this operation follows:

- name: assertSessionDirty
  object: testRunner
  arguments:
    session: *session0

assertSessionNotDirty

The assertSessionNotDirty operation instructs the test runner to assert that the given session is not marked dirty.

The following arguments are supported:

• session: Required string. See commonOptions_session.

An example of this operation follows:

- name: assertSessionNotDirty
  object: testRunner
  arguments:
    session: *session0

assertCollectionExists

The assertCollectionExists operation instructs the test runner to assert that the given collection exists in the database. The test runner MUST use an internal MongoClient for this operation.

The following arguments are supported:

• collectionName: Required string. See commonOptions_collectionName.
• databaseName: Required string. See commonOptions_databaseName.

An example of this operation follows:

- name: assertCollectionExists
  object: testRunner
  arguments:
    collectionName: *collection0Name
    databaseName:  *database0Name

Use a listCollections command to check whether the collection exists. Note that it is currently not possible to run listCollections from within a transaction.

assertCollectionNotExists

The assertCollectionNotExists operation instructs the test runner to assert that the given collection does not exist in the database. The test runner MUST use an internal MongoClient for this operation.

The following arguments are supported:

• collectionName: Required string. See commonOptions_collectionName.
• databaseName: Required string. See commonOptions_databaseName.

An example of this operation follows:

- name: assertCollectionNotExists
  object: testRunner
  arguments:
    collectionName: *collection0Name
    databaseName:  *database0Name

Use a listCollections command to check whether the collection exists. Note that it is currently not possible to run listCollections from within a transaction.

assertIndexExists

The assertIndexExists operation instructs the test runner to assert that an index with the given name exists on the collection. The test runner MUST use an internal MongoClient for this operation.

The following arguments are supported:

• collectionName: Required string. See commonOptions_collectionName.
• databaseName: Required string. See commonOptions_databaseName.
• indexName: Required string. Index name.

An example of this operation follows:

- name: assertIndexExists
  object: testRunner
  arguments:
    collectionName: *collection0Name
    databaseName:  *database0Name
    indexName: t_1

Use a listIndexes command to check whether the index exists. Note that it is currently not possible to run listIndexes from within a transaction.

assertIndexNotExists

The assertIndexNotExists operation instructs the test runner to assert that an index with the given name does not exist on the collection. The test runner MUST use an internal MongoClient for this operation.

The following arguments are supported:

• collectionName: Required string. See commonOptions_collectionName.
• databaseName: Required string. See commonOptions_databaseName.
• indexName: Required string. Index name.

An example of this operation follows:

- name: assertIndexNotExists
  object: testRunner
  arguments:
    collectionName: *collection0Name
    databaseName:  *database0Name
    indexName: t_1

Use a listIndexes command to check whether the index exists. Note that it is currently not possible to run listIndexes from within a transaction.

createEntities

The createEntities operation instructs the test runner to create the provided entities and store them in the current test's Entity Map.

• entities: Required array of one or more entity objects. As with the file-level createEntities directive, test files SHOULD declare entities in dependency order, such that all referenced entities are defined before any of their dependent entities.

An example of this operation follows:

- name: createEntities
  object: testRunner
  arguments:
    entities:
      - client:
          id: &client0 client0
      - database:
          id: &database0 database0
          client: *client0
          databaseName: &database0Name test

loop

The loop operation executes sub-operations in a loop.

The following arguments are supported:

• operations: Required array of operation objects. List of operations (henceforth referred to as sub-operations) to run on each loop iteration. Each sub-operation must be a valid operation as described in Entity Test Operations.

  Sub-operations SHOULD NOT include the loop operation.

  If, in the course of executing sub-operations, a sub-operation yields an error or failure, the test runner MUST NOT execute subsequent sub-operations in the same loop iteration. If storeErrorsAsEntity and/or storeFailuresAsEntity options are specified, the loop MUST store the error/failure accordingly and continue to the next iteration (i.e. the error/failure will not interrupt the test). If neither storeErrorsAsEntity nor storeFailuresAsEntity are specified, the loop MUST terminate and raise the error/failure (i.e. the error/failure will interrupt the test).

• storeErrorsAsEntity: Optional string. If specified, the runner MUST capture errors arising during sub-operation execution and append a document with error information to the array stored in the specified entity.

  If this option is specified, the test runner MUST check the existence and the type of the entity with the specified name before executing the loop. If the entity does not exist, the test runner MUST create it with the type of BSON array. If the entity exists and is of type BSON array, the test runner MUST do nothing. If the entity exists and is of a different type, the test runner MUST raise an error.

  If this option is specified and storeFailuresAsEntity is not, failures MUST also be captured and appended to the array.

  Documents appended to the array MUST contain the following fields:

  • error: the textual description of the error encountered.
  • time: the number of (floating-point) seconds since the Unix epoch when the error was encountered.

• storeFailuresAsEntity: Optional string. If specified, the runner MUST capture failures arising during sub-operation execution and append a document with failure information to the array stored in the specified entity.

  If this option is specified, the test runner MUST check the existence and the type of the entity with the specified name before executing the loop. If the entity does not exist, the test runner MUST create it with the type of BSON array. If the entity exists and is of type BSON array, the test runner MUST do nothing. If the entity exists and is of a different type, the test runner MUST raise an error.

  If this option is specified and storeErrorsAsEntity is not, errors MUST also be captured and appended to the array.

  Documents appended to the array MUST contain the following fields:

  • error: the textual description of the failure encountered.
  • time: the number of (floating-point) seconds since the Unix epoch when the failure was encountered.

• storeSuccessesAsEntity: Optional string. If specified, the runner MUST keep track of the number of sub-operations that completed successfully, and store that number in the specified entity. For example, if the loop contains two sub-operations, and they complete successfully, each loop execution would increment the number of successes by two.

  If the entity of the specified name already exists, the test runner MUST raise an error.

• storeIterationsAsEntity: Optional string. If specified, the runner MUST keep track of the number of iterations of the loop performed, and store that number in the specified entity. The number of loop iterations is counted irrespective of whether sub-operations within the iteration succeed or fail.

  If the entity of the specified name already exists, the test runner MUST raise an error.

A failure is when the result or outcome of an operation executed by the test runner differs from its expected outcome. For example, an expectResult assertion failing to match a BSON document or an expectError assertion failing to match an error message would be considered a failure. An error is any other type of error raised by the test runner. For example, an unsupported operation or inability to resolve an entity name would be considered an error.

This specification permits the test runner to report some failures as errors and some errors as failures. When the test runner stores errors and failures as entities it MAY classify conditions as errors and failures in the same way as it would when used in the driver's test suite. This includes reporting all errors as failures or all failures as errors.

If the test runner does not distinguish errors and failures in its reporting, it MAY report both conditions under either category, but it MUST report any given condition in at most one category.

The following termination behavior MUST be implemented by the test runner:

• The test runner MUST provide a way to request termination of loops. This request will be made by the Atlas testing workload executor in response to receiving the termination signal from Astrolabe.
• When the termination request is received, the test runner MUST stop looping. If the test runner is looping when the termination request is received, the current loop iteration MUST complete to its natural conclusion (success or failure). If the test runner is not looping when the termination request is received, it MUST NOT start any new loop iterations in either the current test or subsequent tests for the lifetime of the test runner.
• The termination request MUST NOT affect non-loop operations, including any operations after the loop. The tests SHOULD NOT be written in such a way that the success or failure of operations that follow loops depends on how many loop iterations were performed.
• Receiving the termination request MUST NOT by itself be considered an error or a failure by the test runner.

The exact mechanism by which the workload executor requests termination of the loop in the test runner, including the respective API, is left to the driver.

Tests SHOULD NOT include multiple loop operations (nested or sequential).

An example of this operation follows:

- name: loop
  object: testRunner
  arguments:
    storeErrorsAsEntity: errors
    storeFailuresAsEntity: failures
    storeSuccessesAsEntity: successes
    storeIterationsAsEntity: iterations
    operations:
      - name: find
        object: *collection0
        arguments:
          filter: { _id: { $gt: 1 }}
          sort: { _id: 1 }
        expectResult:
          - _id: 2, x: 22
          - _id: 3, x: 33

assertNumberConnectionsCheckedOut

The assertNumberConnectionsCheckedOut operation instructs the test runner to assert that the given number of connections are currently checked out for the specified client entity. This operation only applies to drivers that implement connection pooling and should be skipped for drivers that do not.

The following arguments are supported:

• client: Required string. See commonOptions_client.
• connections: Required integer. The number of connections expected to be checked out.

An example of this operation follows:

- name: assertNumberConnectionsCheckedOut
  object: testRunner
  arguments:
    client: *client0
    connections: 1

runOnThread

The runOnThread operation instructs the test runner to schedule an operation to be run on a given thread. The given thread MUST begin executing the operation immediately. runOnThread MUST NOT wait for the operation to complete. If any of the operation's test assertions fail, the entire test case MUST fail as well.

When writing test cases that use runOnThread, it's important to note that certain entities are not concurrency-safe (e.g. sessions, cursors) and therefore SHOULD NOT be used in operations on multiple different threads entities.

The following arguments are supported:

• thread: Required string. Thread entity on which this operation should be scheduled.
• operation: Required operation object. The operation to schedule on the thread. This object must be a valid operation as described in Entity Test Operations.

An example of this operation follows:

- name: runOnThread
  object: testRunner
  arguments:
    thread: *thread0
    operation:
      name: insertOne
      object: *collection0
      arguments:
        document: { _id: 2 }
      expectResult:
        $$unsetOrMatches:
          insertedId: { $$unsetOrMatches: 2 }

waitForThread

The waitForThread operation instructs the test runner to notify the given thread that no more operations are forthcoming, wait for it to complete its last operation, and assert that it exited without any errors.

If the waitForThread operation is not satisfied after 10 seconds, this operation MUST cause a test failure.

The test.operations list SHOULD contain a waitForThread operation for each thread entity that the test creates.

The following arguments are supported:

• thread: Required string. Thread entity that should be stopped and awaited for completion.

An example of this operation follows:

- name: waitForThread
  object: testRunner
  arguments:
    thread: *thread0

waitForEvent

The waitForEvent operation instructs the test runner to wait until the specified MongoClient has published a specific, matching event a given number of times. Note that this includes any events published before the waitForEvent operation started.

If the waitForEvent operation is not satisfied after 10 seconds, this operation MUST cause a test failure.

The following arguments are supported:

• client: Required string. Client entity whose events the runner will be waiting for.
• event: Required expectedEvent object. The event which the test runner is waiting to be observed on the provided client. The assertions laid out in expectedEvent MUST be used to determine if an observed event matches event. event SHOULD have an event type that was included in the client's observeEvents field.
• count: Required integer. The number of matching events to wait for before resuming execution of subsequent operations.

For example, the following instructs the test runner to wait for at least one poolClearedEvent to be published:

- name: waitForEvent
  object: testRunner
  arguments:
    client: *client0
    event:
      poolClearedEvent: {}
    count: 1

assertEventCount

The assertEventCount operation instructs the test runner to assert the specified MongoClient has published a specific, matching event a given number of times so far in the test.

The following arguments are supported:

• client: Required string. Client entity whose events the runner will be counting.
• event: Required expectedEvent object. The event which the test runner will be counting on the provided client. The assertions laid out in expectedEvent MUST be used to determine if an observed event matches event. event SHOULD have an event type that was included in the client's observeEvents field.
• count: Required integer. The exact number of matching events that client should have seen so far.

For example, the following instructs the test runner to assert that a single PoolClearedEvent was published:

- name: assertEventCount
  object: testRunner
  arguments:
    client: *client0
    event:
      poolClearedEvent: {}
    count: 1

recordTopologyDescription

The recordTopologyDescription operation instructs the test runner to retrieve the specified MongoClient's current TopologyDescription and store it in the Entity Map.

The following arguments are supported:

• client: Required string. Client entity whose TopologyDescription will be recorded.
• id: Required string. The name with which the TopologyDescription will be stored in the Entity Map.

For example:

- name: recordTopologyDescription
  object: testRunner
  arguments:
    client: *client0
    id: &postInsertTopology postInsertTopology

assertTopologyType

The assertTopologyType operation instructs the test runner to assert that the given TopologyDescription has a particular TopologyType.

The following arguments are supported:

• topologyDescription: Required string. TopologyDescription entity whose TopologyType will be inspected.
• topologyType: Required string. Expected TopologyType for the TopologyDescription. See SDAM: TopologyType for a list of possible values.

For example:

- name: assertTopologyType
  object: testRunner
  arguments:
    topologyDescription: *postInsertTopology
    topologyType: ReplicaSetWithPrimary

waitForPrimaryChange

The waitForPrimaryChange operation instructs the test runner to wait until the provided MongoClient discovers a different primary from the one in the provided TopologyDescription. If the provided TopologyDescription does not include a primary, then this operation will wait until the client discovers any primary.

The following arguments are supported:

• client: Required string. See commonOptions_client.

  The client entity MUST be the same one from which topologyDescription was derived. Test runners do not need to verify this.

• priorTopologyDescription: Required string. The name of a TopologyDescription entity which will be used to determine if the primary has changed or not.

• timeoutMS: Optional integer. The number of milliseconds to wait for the primary change before timing out and failing the test. If unspecified, a default timeout of 10 seconds MUST be used.

For example:

- name: waitForPrimaryChange
  object: testRunner
  arguments:
    client: *client0
    priorTopologyDescription: *postInsertTopology
    timeoutMS: 1000

wait

The wait operation instructs the test runner to sleep for a provided number of milliseconds.

The following arguments are supported:

• ms: Required integer. The number of milliseconds for which the current test runner thread should sleep.

For example:

- name: wait
  object: testRunner
  arguments:
    ms: 1000

Special Placeholder Value

$$placeholder

Syntax:

{ field: { $$placeholder: 1 } }

This special key-value pair can be used anywhere the value for a key might be specified in an test file. It is intended to act as a placeholder value in contexts where the test runner cannot provide a definite value or may be expected to replace the placeholder with a value that cannot be specified by the test file (e.g. KMS provider credentials). The test runner MUST raise an error if a placeholder value is used in an unexpected context or a replacement cannot be made.

An example of using this placeholder value follows:

kmsProviders:
  aws:
    accessKeyId: { $$placeholder: 1 }
    privateAccessKey: { $$placeholder: 1 }

Note: the test runner is not required to validate the type or value of a $$placeholder field.

Evaluating Matches

Expected values in tests (e.g. operation.expectResult) are expressed as either relaxed or canonical Extended JSON.

The algorithm for matching expected and actual values is specified with the following pseudo-code:

function match (expected, actual):
  if expected is a document:
    // handle special operators (e.g. $$type)
    if first and only key of expected starts with "$$":
      execute any assertion(s) for the special operator
      return

    assert that actual is a document

    for every key/value in expected:
      // handle key-based operators (e.g. $$exists, $$unsetOrMatches)
      if value is a document and its first and only key starts with "$$":
        execute any assertion(s) for the special operator
        continue to the next iteration unless actual value must be matched

      assert that actual[key] exists
      assert that actual[key] matches value

    if expected is not the root document:
      assert that actual does not contain additional keys

    return

  if expected is an array:
    assert that actual is an array
    assert that actual and expected have the same number of elements

    for every index/value in expected:
      assert that actual[index] matches value

    return

  // expected is neither a document nor array
  assert that actual and expected are the same type, noting flexible numerics
  assert that actual and expected are equal

The rules for comparing documents and arrays are discussed in more detail in subsequent sections. When comparing types other than documents and arrays, test runners MAY adopt any of the following approaches to compare expected and actual values, as long as they are consistent:

• Convert both values to relaxed or canonical Extended JSON and compare strings
• Convert both values to BSON, and compare bytes
• Convert both values to native representations, and compare accordingly

When comparing types that contain documents as internal properties (e.g. CodeWScope), the rules in Evaluating Matches do not apply and the documents MUST match exactly; however, test runners MUST permit variation in document key order or otherwise normalize the documents before comparison.

Flexible Numeric Comparisons

When comparing numeric types (excluding Decimal128), test runners MUST consider 32-bit, 64-bit, and floating point numbers to be equal if their values are numerically equivalent. For example, an expected value of 1 would match an actual value of 1.0 (e.g. ok field in a server response) but would not match 1.5.

Allowing Extra Fields in Root-level Documents

When matching root-level documents, test runners MUST permit the actual document to contain additional fields not present in the expected document.

For example, the following documents match:

expected: { x: 1 }
actual: { x: 1, y: 1 }

The inverse is not true. For example, the following documents do not match:

expected: { x: 1, y: 1 }
actual: { x: 1 }

Test runners MUST NOT permit additional fields in nested documents. For example, the following documents do not match:

expected: { x: { y: 1 } }
actual: { x: { y: 1, z: 1 } }

It may be helpful to think of expected documents as a form of query criteria. The intention behind this rule is that it is not always feasible or relevant for a test to exhaustively specify all fields in an expected document (e.g. cluster time in command for CommandStartedEvent).

When the expected value is an array, test runners MUST differentiate between an array of values, which may be documents, (e.g. distinct) and an array of root-level documents derived from an iterable result (e.g. find, aggregate). For example, the following array of documents would not match if returned by distinct, but would match if returned via find (after iterating the cursor):

expected: [ { x: 1 }, { x: 2 } ]
actual: [ { x: 1, y: 1 }, { x: 2, y: 2 } ]

Examples of Root-level Documents

Contexts where one might encounter a root-level document include:

• command for CommandStartedEvent

• reply for CommandSucceededEvent

• expectResult for operations that return a document. Operations include:

  • findOneAndDelete, findOneAndReplace, and findOneAndUpdate
  • iterateUntilDocumentOrError
  • iterateOnce

• expectResult array elements for operations that return an iterable of documents. Operations include:

  • aggregate
  • find)
  • listCollections, listDatabases, and listIndexes
  • listSearchIndexes
  • runCursorCommand

• errorResponse for expectedError

• writeErrors object values for expectedError

• writeConcernErrors array elements for expectedError

• data for expectedLogMessage

Document Key Order Variation

When matching documents, test runners MUST NOT require keys in the expected and actual document to appear in the same order. For example, the following documents would match:

expected: { x: 1, y: 1 }
actual: { y: 1, x: 1 }

Arrays Must Contain the Same Number of Elements

When comparing arrays, expected and actual values MUST contain the same number of elements. For example, the following arrays corresponding to a distinct operation result would not match:

expected: [ 1, 2, 3 ]
actual: [ 1, 2, 3, 4 ]

Special Operators for Matching Assertions

When matching expected and actual values, an equality comparison is not always sufficient. For instance, a test file cannot anticipate what a session ID will be at runtime, but may still want to analyze the contents of an lsid field in a command document. To address this need, special operators can be used.

These operators are objects with a single key identifying the operator. Such keys are prefixed with $$ to ease in detecting an operator (test runners need only inspect the first key of each object) and differentiate the object from MongoDB query operators, which use a single $ prefix. The key will map to some value that influences the operator's behavior (if applicable).

When examining the structure of an expected value during a comparison, test runners MUST check if the value is an object whose first and only key starts with $$ and, if so, defer to the special logic defined in this section.

$$exists

Syntax:

{ field: { $$exists: <boolean> } }

This operator can be used anywhere the value for a key might be specified in an expected document. If true, the test runner MUST assert that the key exists in the actual document, irrespective of its value (e.g. a key with a null value would match). If false, the test runner MUST assert that the key does not exist in the actual document. This operator is modeled after the $exists query operator.

An example of this operator checking for a field's presence follows:

command:
  getMore: { $$exists: true }
  collection: *collectionName,
  batchSize: 5

An example of this operator checking for a field's absence follows:

command:
  update: *collectionName
  updates: [ { q: {}, u: { $set: { x: 1 } } } ]
  ordered: true
  writeConcern: { $$exists: false }

$$type

Syntax:

{ $$type: <string> }
{ $$type: [ <string>, <string>, ... ] }

This operator can be used anywhere a matched value is expected (including expectResult). The test runner MUST assert that the actual value exists and matches one of the expected types, which correspond to the documented string types for the $type query operator.

An example of this operator follows:

command:
  getMore: { $$type: [ "int", "long" ] }
  collection: { $$type: "string" }

When the actual value is an array, test runners MUST NOT examine types of the array's elements. Only the type of actual field SHALL be checked. This is admittedly inconsistent with the behavior of the $type query operator, but there is presently no need for this behavior in tests.

$$matchesEntity

Syntax, where entityName is a string:

{ $$matchesEntity: <entityName> }

This operator can be used to reference a BSON entity anywhere a matched value is expected (including expectResult). If the BSON entity is defined in the current test's Entity Map, the test runner MUST fetch that entity and assert that the actual value matches the entity using the standard rules in Evaluating Matches; otherwise, the test runner MUST raise an error for an undefined or mistyped entity. The YAML file SHOULD use an alias node for the entity name.

This operator does not influence whether or not an actual document value is considered a root-level document.

This operator is primarily used to assert identifiers for uploaded GridFS files.

An example of this operator follows:

operations:
  -
    object: *bucket0
    name: upload
    arguments:
      filename: "filename"
      source: { $$hexBytes: "12AB" }
    expectResult: { $$type: "objectId" }
    saveResultAsEntity: &objectid0 "objectid0"
  - object: *filesCollection
    name: find
    arguments:
      sort: { uploadDate: -1 }
      limit: 1
    expectResult:
      - _id: { $$matchesEntity: *objectid0 }

$$matchesHexBytes

Syntax, where hexBytes is an even number of hexadecimal characters (case-insensitive) and MAY be empty:

{ $$matchesHexBytes: <hexBytes> }

This operator can be used anywhere a matched value is expected (including expectResult) and the actual value is a string. The test runner MUST raise an error if the hexBytes string is malformed. This operator is primarily used to assert the results of download and downloadByName, which return stream contents as a string.

$$unsetOrMatches

Syntax:

{ $$unsetOrMatches: <anything> }

This operator can be used anywhere a matched value is expected (including expectResult), excluding an array element because Arrays Must Contain the Same Number of Elements. The test runner MUST assert that the actual value either does not exist or matches the expected value. Matching the expected value MUST use the standard rules in Evaluating Matches, which means that it may contain special operators.

This operator does not influence whether or not an actual document value is considered a root-level document.

This operator is primarily used to assert driver-optional fields from the CRUD spec (e.g. insertedId for InsertOneResult, writeResult for BulkWriteException).

An example of this operator used for a result's field follows:

expectResult:
  insertedId: { $$unsetOrMatches: 2 }

An example of this operator used for an entire result follows:

expectError:
  expectResult:
    $$unsetOrMatches:
      deletedCount: 0
      insertedCount: 2
      matchedCount: 0
      modifiedCount: 0
      upsertedCount: 0
      upsertedIds: { }

$$sessionLsid

Syntax:

{ $$sessionLsid: <sessionEntityName> }

This operator can be used anywhere a matched value is expected (including expectResult). If the session entity is defined in the current test's Entity Map, the test runner MUST assert that the actual value equals its logical session ID; otherwise, the test runner MUST raise an error for an undefined or mistyped entity. The YAML file SHOULD use an alias node for a session entity's id field (e.g. session: *session0).

An example of this operator follows:

command:
  ping: 1
  lsid: { $$sessionLsid: *session0 }

$$lte

Syntax:

{ $$lte: 5 }

This operator can be used anywhere a matched value is expected (including expectResult). The test runner MUST assert that the actual value is less than or equal to the specified value. Test runners MUST also apply the rules specified in Flexible Numeric Comparisons for this operator. For example, an expected value of 1 would match an actual value of 1.0 and 0.0 but would not match 1.1.

$$matchAsDocument

Syntax:

{ $$matchAsDocument: <anything> }

This operator may be used anywhere a matched value is expected (including expectResult) and the actual value is an extended JSON string. The test runner MUST parse the actual value into a BSON document and match it against the expected value.

Matching the expected value MUST use the standard rules in Evaluating Matches, which means that it may contain special operators. The actual value MUST NOT be considered a root-level document (i.e. extra fields are not permitted); however, $$matchAsRoot may be used to change that behavior.

This operator is primarily used to assert on extended JSON commands and command replies included in log messages.

$$matchAsRoot

This operator may be used anywhere a matched value is expected (including expectResult) and the expected and actual values are documents. The test runner MUST treat the actual value as a root-level document as described in Evaluating Matches and match it against the expected value.

Test Runner Implementation

The sections below describe instructions for instantiating the test runner, loading each test file, and executing each test within a test file. Test runners MUST NOT share state created by processing a test file with the processing of subsequent test files, and likewise for tests within a test file.

Initializing the Test Runner

The test runner MUST be configurable with a connection string (or equivalent configuration), which will be used to initialize any internal MongoClient(s) and any client entities (in combination with other URI options). This specification is not prescriptive about how this information is provided. For example, it may be read from an environment variable or configuration file.

Create a new MongoClient, which will be used for internal operations (e.g. processing initialData and test.outcome). This is referred to elsewhere in the specification as the internal MongoClient. If this MongoClient would connect multiple mongos nodes and the driver does not provide a way to target operations to specific servers, the test runner MAY construct internal MongoClients for each mongos.

Determine the server version and topology type using an internal MongoClient. This information will be used to evaluate any future runOnRequirement checks. Test environments SHOULD NOT use mixed version clusters, so it is not necessary to check multiple servers.

In addition to the aforementioned connection string, the test runner MUST also be configurable with two other connection strings (or equivalent configuration) that point to TCP load balancers: one fronting multiple servers and one fronting a single server. These will be used to initialize client entities when executing tests against a load balanced sharded cluster. If the topology type is LoadBalanced and Atlas Serverless is not being used, the test runner MUST error if either of these URIs is not provided. When testing against other topology types or Atlas Serverless, these URIs SHOULD NOT be provided and MUST be ignored if provided.

The test runner SHOULD terminate any open transactions (see: Terminating Open Transactions) using the internal MongoClient(s) before executing any tests.

Executing a Test File

The instructions in this section apply for each test file loaded by the test runner.

Test files, which may be YAML or JSON files, MUST be interpreted using an Extended JSON parser. The parser MUST accept relaxed and canonical Extended JSON (per Extended JSON: Parsers), as test files may use either.

Upon loading a file, the test runner MUST read the schemaVersion field and determine if the test file can be processed further. Test runners MAY support multiple versions and MUST NOT process incompatible files (as discussed in Test Runner Support). If a test file is incompatible, test runners MUST raise an error and MAY do so by reporting a test failure. Test runners MAY make an effort to infer the number of tests (and their descriptions) from an incompatible file and report a failure for each test.

If runOnRequirements is specified, the test runner MUST skip the test file unless one or more runOnRequirement objects are satisfied.

For each element in tests, follow the process in Executing a Test.

Executing a Test

The instructions in this section apply for each test occurring in a test file loaded by the test runner. After processing a test, test runners MUST reset any internal state that resulted from doing so. For example, the Entity Map created for one test MUST NOT be shared with another.

If at any point while executing this test an unexpected error is encountered or an assertion fails, the test runner MUST consider this test to have failed and SHOULD continue with the instructions in this section to ensure that the test environment is cleaned up (e.g. disable fail points, kill sessions) while also forgoing any additional assertions.

If test.skipReason is specified, the test runner MUST skip this test and MAY use the string value to log a message.

If test.runOnRequirements is specified, the test runner MUST skip the test unless one or more runOnRequirement objects are satisfied.

If initialData is specified, for each collectionData therein the test runner MUST set up the collection. All setup operations MUST use the internal MongoClient and a "majority" write concern. The test runner MUST first drop the collection. If a createOptions document is present, the test runner MUST execute a create command to create the collection with the specified options. The test runner MUST then insert the specified documents (if any). If no documents are present and createOptions is not set, the test runner MUST create the collection. If the topology is sharded, the test runner SHOULD use a single mongos for handling initialData to avoid possible runtime errors.

If the test might execute a transaction against a sharded deployment, the test runner MUST collect the latest cluster time from processing initialData. See MigrationConflict Errors on Sharded Clusters for more information.

Create a new Entity Map that will be used for this test. If createEntities is specified, the test runner MUST create each entity accordingly and add it to the map. If the topology is a sharded cluster, the test runner MUST handle useMultipleMongoses accordingly if it is specified for any client entities. If the topology type is LoadBalanced, client entities MUST be initialized with the appropriate load balancer connection string as discussed in useMultipleMongoses.

If the test might execute a transaction against a sharded deployment, the test runner MUST advance the cluster time of any session entities created during the test using the cluster time collected from processing initialData. See MigrationConflict Errors on Sharded Clusters for more information.

If the test might execute a distinct command within a sharded transaction, for each target collection the test runner SHOULD execute a non-transactional distinct command on each mongos server using an internal MongoClient. See StaleDbVersion Errors on Sharded Clusters for more information.

If the test might execute a configureFailPoint command, for each target client the test runner MAY specify a reduced value for heartbeatFrequencyMS (and minHeartbeatFrequencyMS if possible) to speed up SDAM recovery time and server selection after a failure; however, test runners MUST NOT do so for any client that specifies heartbeatFrequencyMS in its uriOptions.

For each client entity where observeEvents has been specified, the test runner MUST enable all event listeners necessary to collect the specified event types. Test runners MAY leave event listeners disabled for tests that do not assert events (i.e. tests that omit both test.expectEvents and special operations such as assertSameLsidOnLastTwoCommands).

For each client with command monitoring enabled, the test runner MUST ignore events for the following:

• Any command(s) specified in ignoreCommandMonitoringEvents.
• Any configureFailPoint commands executed for failPoint and targetedFailPoint operations.
• Any commands containing sensitive information (per the Command Logging and Monitoring spec) unless observeSensitiveCommands is true. Note that drivers will redact commands and replies for sensitive commands. For hello and legacy hello, which are conditionally sensitive based on the presence of a speculativeAuthenticate field, the test runner may need to infer that the events are sensitive based on whether or not the command and reply documents are redacted (i.e. empty documents).

For each element in test.operations, follow the process in Executing an Operation. If an unexpected error is encountered or an assertion fails, the test runner MUST consider this test to have failed.

If any event listeners were enabled on any client entities, the test runner MUST now disable those event listeners.

If any fail points were configured, the test runner MUST now disable those fail points (on the same server) to avoid spurious failures in subsequent tests. For any fail points configured using targetedFailPoint, the test runner MUST disable the fail point on the same mongos server on which it was originally configured. See Disabling Fail Points for more information.

If test.expectEvents is specified, for each object therein the test runner MUST assert that the number and sequence of expected events match the number and sequence of actual events observed on the specified client. If the list of expected events is empty, the test runner MUST assert that no events were observed on the client. The process for matching events is described in expectedEvent.

If test.outcome is specified, for each collectionData therein the test runner MUST assert that the collection contains exactly the expected data. The test runner MUST query each collection using the internal MongoClient, an ascending sort order on the _id field (i.e. { _id: 1 }), a "primary" read preference, and a "local" read concern. When comparing collection data, the rules in Evaluating Matches do not apply and the documents MUST match exactly; however, test runners MUST permit variations in document key order or otherwise normalize the documents before comparison. If the list of documents is empty, the test runner MUST assert that the collection is empty.

Before clearing the entity map at the end of each test, the test runner MUST allow its entities to be accessed externally. The exact mechanism for facilitating this access is not prescribed by this specification, but drivers should be mindful of concurrency if applicable. As an example, the test runner MAY be configured with a callback method, which will be invoked at the end of each test and provided with the entity map (or an equivalent data structure). As previously discussed in Entity Map, test runners MAY restrict access to driver objects if necessary.

Clear the entity map for this test. For each ClientSession in the entity map, the test runner MUST end the session (e.g. call endSession). For each ChangeStream and FindCursor in the entity map, the test runner MUST close the cursor.

If the test started a transaction (i.e. executed a startTransaction or withTransaction operation), the test runner MUST terminate any open transactions (see: Terminating Open Transactions).

Proceed to the subsequent test.

Executing an Operation

The instructions in this section apply for each operation occurring in a test contained within a test file loaded by the test runner.

If at any point while executing an operation an unexpected error is encountered or an assertion fails, the test runner MUST consider the parent test to have failed and proceed from Executing a Test accordingly.

If operation.object is "testRunner", this is a special operation. If operation.name is defined in Special Test Operations, the test runner MUST execute the operation accordingly and, if successful, proceed to the next operation in the test; otherwise, the test runner MUST raise an error for an undefined operation. The test runner MUST keep a record of any fail points configured by special operations so that they may be disabled after the current test.

If operation.object is not "testRunner", this is an entity operation. If operation.object is defined in the current test's Entity Map, the test runner MUST fetch that entity and note its type; otherwise, the test runner MUST raise an error for an undefined entity. If operation.name does not correspond to a known operation for the entity type (per Entity Test Operations), the test runner MUST raise an error for an unsupported operation. Test runners MAY skip tests that include operations that are intentionally unimplemented (e.g. listCollectionNames).

Proceed with preparing the operation's arguments. If session is specified in operation.arguments, the test runner MUST resolve it to a session entity and MUST raise an error if the name is undefined or maps to an unexpected type. If a key in operation.arguments does not correspond to a known parameter/option for the operation, the test runner MUST raise an error for an unsupported argument.

Before executing the operation, the test runner MUST be prepared to catch a potential error from the operation (e.g. enter a try block). Proceed with executing the operation and capture its result or error.

Note that some operations require special handling, as discussed in Entity Test Operations. For example, model objects may need to be converted to documents (before matching or saving in the entity map) and returned iterables may need to be fully iterated.

If operation.ignoreResultAndError is true, the test runner MUST NOT make any assertions regarding the result or error of the operation and MUST proceed to the subsequent operation.

If operation.expectError is specified, the test runner MUST assert that the operation yielded an error; otherwise, the test runner MUST assert that the operation did not yield an error. If an error was expected, the test runner MUST evaluate any assertions in expectedError accordingly.

If operation.expectResult is specified, the test MUST assert that it matches the actual result of the operation according to the rules outlined in Evaluating Matches.

If operation.saveResultAsEntity is specified, the test runner MUST store the result in the current test's entity map using the specified name. If the operation did not return a result or the result does not comply with Supported Entity Types then the test runner MUST raise an error.

After asserting the operation's error and/or result and optionally saving the result, proceed to the subsequent operation.

Special Procedures

This section describes some procedures that may be referenced from earlier sections.

Terminating Open Transactions

Open transactions can cause tests to block indiscriminately. When connected to MongoDB 3.6 or later, test runners SHOULD terminate all open transactions at the start of a test suite and after each failed test by killing all sessions in the cluster. Using the internal MongoClient(s), execute the killAllSessions command on either the primary or, if connected to a sharded cluster, each mongos server.

For example:

db.adminCommand({
  killAllSessions: []
});

The test runner MAY ignore the following command failures:

• Interrupted(11601) to work around SERVER-38335.
• Unauthorized(13) to work around SERVER-54216.
• CommandNotFound(59) if the command is executed on a pre-3.6 server

Note that Atlas, by design, does not allow database users to kill sessions belonging to other users. This makes it impossible to guarantee that an existing transaction will not block test execution. To work around this, test runners SHOULD either ignore Unauthorized(13) command failures or avoid calling killAllSessions altogether when connected to Atlas (e.g. by detecting mongodb.net in the hostname or allowing the test runner to be configured externally).

Test runners MUST NOT execute killAllSessions when connected to Atlas Data Lake.

MigrationConflict Errors on Sharded Clusters

Following SERVER-82353, drivers may encounter MigrationConflict errors when executing transactions on sharded clusters due to an outdated cluster time. For example:

Transaction fe0b9a7d-4b64-4e38-aad2-4c7dd5ab0c2b - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - :1 was aborted on statement 0 due to: a non-retryable snapshot error :: caused by :: Encountered error from localhost:27217 during a transaction :: caused by :: Database transaction-tests has undergone a catalog change operation at time Timestamp(1708062645, 94) and no longer satisfies the requirements for the current transaction which requires Timestamp(1708062645, 93). Transaction will be aborted.

To work around this issue, a test runner MUST collect the latest cluster time from processing initialData, which is executed using the internal MongoClient, and use it to advance the cluster time of every session entity created during the test, by either createEntities or the special test operation). This will ensure that the cluster time is gossipped to any other mongo hosts that may be used to execute a transaction during the test.

Depending on the test runner implementation, the cluster time may be collected in various ways. For example:

• Execute a ping command against the same mongos host used for initialData and read the $clusterTime response field
• Execute all operations for initialData using an explicit session and read its cluster time after the last operation.

This logic is only necessary for tests that might execute a transaction against a sharded deployment transaction (i.e. test.operations includes startTransaction or withTransaction and the topology is sharded or load-balanced). To ease the implementation, test runners MAY apply this logic to every test.

StaleDbVersion Errors on Sharded Clusters

When a shard receives its first command that contains a databaseVersion, the shard returns a StaleDbVersion error and mongos retries the operation. In a sharded transaction, mongos does not retry these operations and instead returns the error to the client. For example:

Command distinct failed: Transaction aa09e296-472a-494f-8334-48d57ab530b6:1 was aborted on statement 0 due to: an error from cluster data placement change :: caused by :: got stale databaseVersion response from shard sh01 at host localhost:27217 :: caused by :: don't know dbVersion.

To work around this limitation, a test runners MUST execute a non-transactional distinct command on each mongos server before running any test that might execute distinct within a transaction. To ease the implementation, test runners MAY execute distinct before every test.

Test runners can remove this workaround once SERVER-39704 is resolved, after which point mongos should retry the operation transparently. The distinct command is the only command allowed in a sharded transaction that uses the databaseVersion concept so it is the only command affected.

Server Fail Points

Many tests utilize the configureFailPoint command to trigger server-side errors such as dropped connections or command errors. Tests can configure fail points using the special failPoint or targetedFailPoint operations.

This internal command is not documented in the MongoDB manual (pending DOCS-10784); however, there is scattered documentation available on the server wiki (The "failCommand" Fail Point) and employee blogs (e.g. Intro to Fail Points, Testing Network Errors With MongoDB). Documentation can also be gleaned from JIRA tickets (e.g. SERVER-35004, SERVER-35083). This specification does not aim to provide comprehensive documentation for all fail points available for driver testing, but some fail points are documented in Fail Points Commonly Used in Tests.

Configuring Fail Points

The configureFailPoint command is executed on the admin database and has the following structure:

db.adminCommand({
    configureFailPoint: <string>,
    mode: <string|object>,
    data: <object>
});

The value of configureFailPoint is a string denoting the fail point to be configured (e.g. "failCommand").

The mode option is a generic fail point option and may be assigned a string or object value. The string values "alwaysOn" and "off" may be used to enable or disable the fail point, respectively. An object may be used to specify either times or skip, which are mutually exclusive:

• { times: <integer> } may be used to limit the number of times the fail point may trigger before transitioning to "off".
• { skip: <integer> } may be used to defer the first trigger of a fail point, after which it will transition to "alwaysOn".

The data option is an object that may be used to specify any options that control the particular fail point's behavior.

In order to use configureFailPoint, the undocumented enableTestCommands server parameter must be enabled by either the configuration file or command line option (e.g. --setParameter enableTestCommands=1). It cannot be enabled at runtime via the setParameter command). This parameter should already be enabled for most configuration files in mongo-orchestration.

Disabling Fail Points

A fail point may be disabled like so:

db.adminCommand({
    configureFailPoint: <string>,
    mode: "off"
});

Fail Points Commonly Used in Tests

failCommand

The failCommand fail point allows the client to force the server to return an error for commands listed in the data.failCommands field. Additionally, this fail point is documented in server wiki: The failCommand Fail Point.

The failCommand fail point was introduced in mongod 4.0.0 (SERVER-34551) and mongos 4.1.5 (SERVER-35518); however, the fail point was not usable for testing on mongos until version 4.1.7 (SERVER-34943).

The failCommand fail point may be configured like so:

db.adminCommand({
    configureFailPoint: "failCommand",
    mode: <string|object>,
    data: {
      failCommands: [<string>, ...],
      closeConnection: <boolean>,
      errorCode: <integer>,
      errorLabels: [<string>, ...],
      writeConcernError: <object>,
      appName: <string>,
      blockConnection: <boolean>,
      blockTimeMS: <integer>,
      namespace: <string>,
    }
});

failCommand supports the following data options, which may be combined if desired:

• failCommands: Required array of strings. Lists the command names to fail.
• closeConnection: Optional boolean, which defaults to false. If true, the command will not be executed, the connection will be closed, and the client will see a network error.
• errorCode: Optional integer, which is unset by default. If set, the command will not be executed and the specified command error code will be returned as a command error.
• errorLabels: Optional array of strings. If set, this list overrides the server's normal behavior for adding error labels. An empty array may be used to suppress the server from adding error labels to the response. New in server 4.3.1 (SERVER-43941).
• appName: Optional string, which is unset by default. If set, the fail point will only apply to connections for MongoClients created with this appname. New in server 4.4.0-rc2 and backported to 4.2.9 (SERVER-47195).
• blockConnection: Optional boolean, which defaults to false. If true, the server should block the affected commands for blockTimeMS. New in server 4.3.4 and backported to 4.2.9 (SERVER-41070).
• blockTimeMS: Optional integer, which is required when blockConnection is true. The number of milliseconds for which the affected commands should be blocked. New in server 4.3.4 and backported to 4.2.9 (SERVER-41070).
• namespace: Optional string. If set, the fail point will only trigger for commands on the specified namespace (e.g. db.coll). New in server 4.3.1 and backported to 4.2.6 (SERVER-43011).

onPrimaryTransactionalWrite

The onPrimaryTransactionalWrite fail point allows the client to force a network error before the server would return a write result to the client. The fail point also allows control whether the server will successfully commit the write via its failBeforeCommitExceptionCode option. Keep in mind that the fail point only triggers for transaction writes (i.e. write commands including txnNumber and lsid fields).

The onPrimaryTransactionalWrite fail point was introduced in mongod 3.6.0 (SERVER-29606) to facilitate testing of retryable writes. It is only supported on mongod and cannot be used with sharded clusters.

onPrimaryTransactionalWrite supports the following data options:

• closeConnection: Optional boolean, which defaults to true. If true, the connection on which the write is executed will be closed before a result can be returned.
• failBeforeCommitExceptionCode: Optional integer, which is unset by default. If set, the specified exception code will be thrown and the write will not be committed. If unset, the write will be allowed to commit.

Determining if a Sharded Cluster Uses Replica Sets

When connected to a mongos server, the test runner can query the config.shards collection. Each shard in the cluster is represented by a document in this collection. If the shard is backed by a single server, the host field will contain a single host. If the shard is backed by a replica set, the host field contain the name of the replica followed by a forward slash and a comma-delimited list of hosts.

Note: MongoDB 3.6+ requires that all shard servers be replica sets.

Design Rationale

This specification was primarily derived from the test formats used by the Transactions and CRUD specs, which have served models or other specs.

This specification commonly uses "SHOULD" when providing guidance on writing test files. While this may appear contradictory to the driver mantra preferring "MUST", it is intentional. Some of this guidance addresses style (e.g. adding comments, using YAML anchors) and cannot be enforced with a JSON schema. Other guidance needs to be purposefully ignored in order to test the test runner implementation (e.g. defining entities out of order to trigger runtime errors). The specification does prefer "MUST" in other contexts, such as discussing parts of the test file format that are enforceable by the JSON schema or the test runner implementation.

Why can't observeSensitiveCommands be true when authentication is enabled?

When running against authentication-enabled clusters, the events observed by a client will always begin with auth-related commands (e.g. authenticate, saslStart, saslContinue) because the MongoClient will need to authenticate a connection before issuing the first command in the test specification. Since the exact form of the authentication command event will depend on whether authentication is enabled, as well as, the auth mechanism in use, it is not possible to anticipate the command monitoring output and perform the appropriate assertions. Consequently, we have restricted use of this property to situations where authentication is disabled on the server. This allows tests to explicitly test sensitive commands via the runCommand helper.

Breaking Changes

This section is reserved for future use. Any breaking changes to the test format SHOULD be described here in detail for historical reference, in addition to any shorter description that may be added to the Changelog.

Future Work

Assert expected log messages

When drivers support standardized logging, the test format may need to support assertions for messages expected to be logged while executing operations. Since log messages are strings, this may require an operator to match regex patterns within strings. Additionally, the test runner may need to support ignoring extra log output, similar to ignoreExtraEvents.

Target failPoint by read preference

The failPoint operation currently uses a "primary" read preference. To date, no spec has needed behavior to configure a fail point on a non-primary node. If the need does arise, failPoint can be enhanced to support a readPreference argument.

IO operations for GridFS streams

Original GridFS spec tests refer to "upload", "download", and "download_by_name" methods, which allow the tests to abstract stream IO and either upload a byte sequence or assert a downloaded byte sequence. These operations correspond to the download, downloadByName, upload, and uploadWithId Bucket Operations.

In order to support methods such as downloadToStream, openUploadStream, and openUploadStreamWithId, test runners would need to represent streams as entities and support IO operations to directly read from and write to a stream entity. This may not be worth the added complexity if the existing operations provide adequate test coverage for GridFS implementations.

Support Client-side Encryption integration tests

Supporting client-side encryption spec tests will require the following changes to the test format:

• json_schema will need to be specified when creating a collection, via either the collection entity definition or initialData.
• key_vault_data can be expressed via initialData
• autoEncryptOpts will need to be specified when defining a client entity. Preparation of this field may require reading AWS credentials from environment variables.

The process for executing tests should not require significant changes, but test files will need to express a dependency on mongocryptd.

Incorporate referenced entity operations into the schema version

The Schema Version is not impacted by changes to operations defined in other specs and referenced in Entity Test Operations (e.g. find for CRUD). The operation.name and operation.arguments fields are loosely defined in the JSON schema as string and object types, respectively.

Ideally, all operations (and their arguments) would be enforced by the JSON schema and any changes to operations would affect the schema version accordingly. For example, a new find option would warrant a minor version bump both for the CRUD spec and this spec and its schema.

As discussed in Executing an Operation, test runners MUST raise errors for unsupported operations and arguments. This is a concession until such time that better processes can be established for versioning other specs and collating spec changes developed in parallel or during the same release cycle.

Changelog

• 2024-10-31: Test operations array may be empty.

• 2024-10-29: List more examples of root-level documents

• 2024-10-24: Document namespace option for failCommand fail point.

• 2024-09-18: Note that failCommand appName option was backported

• 2024-05-08: Schema version 1.21.

  Add writeErrors and writeConcernErrors field to expectedError for the client-level bulk write API.

• 2024-04-15: Note that when directConnection is set to true test runners should only provide a single seed.

• 2024-03-25: Schema version 1.20.

  Add previousDescription and newDescription assertions to topologyDescriptionChangedEvent when checking events with expectEvents

• 2024-03-11: Note that killAllSessions should not be executed on Atlas Data Lake

• 2024-02-27: Document onPrimaryTransactionalWrite fail point, which is used in retryable writes tests.

• 2024-02-23: Require test runners to gossip cluster time from internal MongoClient to each session entity.

• 2024-02-14: Clarify that errors raised from callback operations should always propagate to withTransaction.

• 2024-02-12: Clarify that targetedFailPoint should only be used when useMultipleMongoses is true and not on load-balanced topologies.

• 2024-02-06: Migrated from reStructuredText to Markdown.

• 2024-01-17: Schema version 1.19.

  Add authMechanism to runOnRequirement and require that uriOptions supports placeholder documents.

• 2024-01-11: Schema version 1.18.

  Allow named KMS providers in kmsProviders. Note location of Client-Side Encryption test credentials.

• 2024-01-03: Document server version requirements for errorLabels and blockConnection options for failCommand fail point.

• 2023-10-04: Schema version 1.17.

  Add serverHeartbeatStartedEvent, serverHeartbeatSucceededEvent, and serverHeartbeatFailedEvent for asserting on SDAM server heartbeat events.

• 2023-09-25: Clarify that the UTR is intended to be run against enterprise servers.

• 2022-07-18: Schema version 1.16.

  Add ignoreMessages and ignoreExtraMessages fields to expectedLogMessagesForClient section.

• 2023-06-26: runOnRequirement.csfle should check for crypt_shared and/or mongocryptd.

• 2023-06-13: Schema version 1.15.

  Add databaseName field to CommandFailedEvent and CommandSucceededEvent.

• 2023-05-26: Schema version 1.14.

  Add topologyDescriptionChangedEvent.

• 2023-05-17: Add runCursorCommand and createCommandCursor operations. Added commandCursor entity type which can be used with existing cursor operations.

• 2023-05-12: Deprecate "sharded-replicaset" topology type. Note that server 3.6+ requires replica sets for shards, which is also relevant to load balanced topologies.

• 2023-04-13: Remove readConcern and writeConcern options from runCommand operation.

• 2023-02-24: Fix typo in the description of the $$matchAsRoot matching operator.

• 2022-10-17: Add description of a close operation for client entities.

• 2022-10-14: Schema version 1.13.

  Add support for logging assertions via the observeLogMessages field for client entities, along with a new top-level field expectLogMessages containing expectedLogMessagesForClient objects. Add new special matching operators to enable command logging assertions, $$matchAsDocument and $$matchAsRoot.

• 2022-10-14: Schema version 1.12.

  Add errorResponse to expectedError.

• 2022-10-05: Remove spec front matter, add "Current Schema Version" field, and reformat changelog. Add comment to remind editors to note schema version bumps in changelog updates (where applicable).

• 2022-09-02: Schema version 1.11.

  Add interruptInUseConnections field to poolClearedEvent

• 2022-07-28: Schema version 1.10.

  Add support for thread entities (runOnThread, waitForThread), TopologyDescription entities (recordTopologyDescription, waitForPrimaryChange, assertTopologyType), testRunner event assertion operations (waitForEvent, assertEventCount), expected SDAM events, and the wait operation.

• 2022-07-27: Retroactively note schema version bumps in the changelog and require doing so for future changes.

• 2022-07-11: Update Future Work to reflect that support for ignoring extra observed events was added in schema version 1.7.

• 2022-06-16: Require server 4.2+ for csfle: true.

• 2022-05-10: Add reference to Client Side Encryption spec under ClientEncryption Operations.

• 2022-04-27: Schema version 1.9.

  Added createOptions field to initialData, introduced a new timeoutMS field in collectionOrDatabaseOptions, and added an isTimeoutError field to expectedError. Also introduced the createEntities operation.

• 2022-04-27: Schema version 1.8.

  Add runOnRequirement.csfle.

• 2022-04-26: Add clientEncryption entity and $$placeholder syntax.

• 2022-04-22: Revise useMultipleMongoses and "Initializing the Test Runner" for Atlas Serverless URIs using a load balancer fronting a single proxy.

• 2022-03-01: Schema version 1.7.

  Add ignoreExtraEvents field to expectedEventsForClient.

• 2022-02-24: Rename Versioned API to Stable API

• 2021-08-30: Schema version 1.6.

  Add hasServerConnectionId field to commandStartedEvent, commandSuccededEvent and commandFailedEvent.

• 2021-08-30: Test runners may create an internal MongoClient for each mongos. Better clarify how internal MongoClients may be used. Clarify that drivers creating an internal MongoClient for each mongos should use those clients for targetedFailPoint operations.

• 2021-08-23: Allow runOnRequirement conditions to be evaluated in any order.

• 2021-08-09: Updated all existing schema files to require at least one element in test.expectEvents if specified.

• 2021-07-29: Note that events for sensitive commands will have redacted commands and replies when using observeSensitiveCommands, and how that affects conditionally sensitive commands such as hello and legacy hello.

• 2021-07-01: Note that expectError.expectResult should use $$unsetOrMatches when the result is optional.

• 2021-06-09: Schema version 1.5.

  Added an observeSensitiveCommands property to the client entity type.

• 2021-05-17: Ensure old JSON schema files remain in place

• 2021-04-19: Schema version 1.4.

  Introduce serverless runOnRequirement.

• 2021-04-12: Schema version 1.3.

  Added a FindCursor entity type. Defined a set of cursor operations. Added an auth property to runOnRequirements and modified the topologies property to accept load-balanced. Added CMAP events to the possible event types for expectedEvent. Add assertNumberConnectionsCheckedOut operation. Add ignoreResultAndError operation option.

• 2021-04-08: List additional error codes that may be ignored when calling killAllSessions and note that the command should not be called when connected to Atlas.

• 2021-03-22: Split serverApi into its own section. Note types for loop operation arguments. Clarify how loop iterations are counted for storeIterationsAsEntity.

• 2021-03-10: Clarify that observedAt field measures time in seconds for storeEventsAsEntities.

• 2021-03-09: Clarify which components of a version string are relevant for comparisons.

• 2021-03-04: Change storeEventsAsEntities from a map to an array of storeEventsAsEntity objects.

• 2021-03-01: Schema version 1.2.

  Added storeEventsAsEntities option for client entities and loop operation, which is needed for Atlas Driver Testing.

• 2020-12-23: Clarify how JSON schema is renamed for new minor versions.

• 2020-11-06: Schema version 1.1.

  Added serverApi option for client entities, _yamlAnchors property to define values for later use in YAML tests, and serverParameters property for runOnRequirements.