API Reference

Complete reference for all public classes and methods in the CosmosDB.InMemoryEmulator packages.

See also: Getting Started · Choosing Your Approach · Setup Guide · SQL Queries · Known Limitations

Package: CosmosDB.InMemoryEmulator

`InMemoryCosmos` (Static)

Entry point for creating in-memory Cosmos DB test infrastructure. New in 3.0.0.

Member	Type	Description
`DefaultDatabaseName`	`string`	`"default"` — default database for `AddContainer()`

Method	Returns	Description
`Create(containerName, partitionKeyPath, ...)`	`InMemoryCosmosResult`	Single-container setup (one-liner)
`Create(containerName, partitionKeyPaths, ...)`	`InMemoryCosmosResult`	Single-container with hierarchical PK
`Builder()`	`InMemoryCosmosBuilder`	Multi-container/advanced builder

`InMemoryCosmosBuilder`

Method	Returns	Description
`AddContainer(name, pkPath, configure?)`	`InMemoryCosmosBuilder`	Add container to default database
`AddContainer(name, pkPaths, configure?)`	`InMemoryCosmosBuilder`	Add container with hierarchical PK
`AddDatabase(dbName, configure)`	`InMemoryCosmosBuilder`	Add a named database with containers
`WrapHandler(wrapper)`	`InMemoryCosmosBuilder`	Add HTTP handler wrapper
`ConfigureOptions(configure)`	`InMemoryCosmosBuilder`	Configure `CosmosClientOptions`
`Build()`	`InMemoryCosmosResult`	Build the setup

`InMemoryCosmosResult` : `IDisposable`, `IAsyncDisposable`

Member	Type	Description
`Client`	`CosmosClient`	The in-memory-backed `CosmosClient`
`Container`	`Container`	SDK Container (single-container only)
`Containers`	`IReadOnlyDictionary<string, Container>`	All SDK Containers by name
`Handler`	`FakeCosmosHandler`	Handler (single-container only)
`Handlers`	`IReadOnlyDictionary<string, FakeCosmosHandler>`	All handlers by name

Method	Returns	Description
`SetupContainer(name?)`	`IContainerTestSetup`	Test setup for a container (registration)
`GetHandler(name)`	`FakeCosmosHandler`	Handler for a named container
`SetFaultInjector(injector)`	`void`	Set/clear fault injector on all handlers
`Database(dbName)`	`InMemoryDatabaseResult`	Database-scoped access
`Databases`	`IReadOnlyDictionary<string, InMemoryDatabaseResult>`	All databases
`ExportState(name?)`	`string`	Export container state as JSON
`ExportStateToFile(path, name?)`	`void`	Export container state to a file
`ImportState(json, name?)`	`void`	Import container state from JSON
`ImportStateFromFile(filePath, name?)`	`void`	Import container state from a file
`RestoreToPointInTime(timestamp, name?)`	`void`	Restore container to a point in time
`ClearItems(name?)`	`void`	Remove all items from the container

`InMemoryDatabaseResult`

Member	Type	Description
`DatabaseName`	`string`	The database name
`Containers`	`IReadOnlyDictionary<string, Container>`	Containers in this database
`Handlers`	`IReadOnlyDictionary<string, FakeCosmosHandler>`	Handlers in this database

Method	Returns	Description
`SetupContainer(name)`	`IContainerTestSetup`	Test setup for a container in this database
`GetHandler(name)`	`FakeCosmosHandler`	Handler for a container in this database
`SetFaultInjector(injector)`	`void`	Set/clear fault injector on this database's handlers
`ExportState(name)`	`string`	Export container state as JSON
`ExportStateToFile(name, path)`	`void`	Export container state to a file
`ImportState(name, json)`	`void`	Import container state from JSON
`ImportStateFromFile(name, filePath)`	`void`	Import container state from a file
`RestoreToPointInTime(name, timestamp)`	`void`	Restore container to a point in time
`ClearItems(name)`	`void`	Remove all items from the container

`IContainerTestSetup`

Focused interface for test-only operations. Implemented internally by InMemoryContainer.

Property	Type	Description
`DefaultTimeToLive`	`int?`	Container-level TTL in seconds
`FeedRangeCount`	`int`	Number of feed ranges (default 1). Set > 1 to simulate multiple physical partitions
`MaxChangeFeedSize`	`int`	Maximum change feed entries retained (default 1000). Set to `0` for unbounded
`StateFilePath`	`string?`	Path for automatic state persistence
`ItemCount`	`int`	Number of items currently stored
`PartitionKeyPaths`	`IReadOnlyList<string>`	Partition key path(s)
`JsTriggerEngine`	`IJsTriggerEngine?`	JavaScript trigger engine
`SprocEngine`	`ISprocEngine?`	JavaScript stored procedure engine

Method	Returns	Description
`RegisterStoredProcedure(name, handler)`	`void`	Register C# stored procedure
`RegisterStoredProcedure(name, jsBody)`	`void`	Register JS stored procedure (requires JsTriggers package)
`RegisterUdf(name, handler)`	`void`	Register C# UDF
`RegisterUdf(name, jsBody)`	`void`	Register JS UDF (requires JsTriggers package)
`RegisterTrigger(name, type, operation, handler)`	`void`	Register C# trigger
`RegisterTrigger(name, type, operation, jsBody)`	`void`	Register JS trigger (requires JsTriggers package)
`ExportState()`	`string`	Export container state as JSON
`ExportStateToFile(path)`	`void`	Export container state to a file
`ImportState(json)`	`void`	Import container state from JSON
`ImportStateFromFile(filePath)`	`void`	Import container state from a file
`RestoreToPointInTime(timestamp)`	`void`	Restore container to a point in time via change feed replay
`ClearItems()`	`void`	Remove all items from the container

`FakeCosmosHandler`

HTTP message handler that intercepts Cosmos SDK requests and serves them from an in-memory container. Used internally by all integration approaches — see the Setup Guide for usage examples. Obtain via InMemoryCosmosResult.Handler or InMemoryCosmosResult.GetHandler(name).

Namespace: CosmosDB.InMemoryEmulator
Inherits: System.Net.Http.HttpMessageHandler

Note: Constructors are internal. Use InMemoryCosmos.Create() or InMemoryCosmos.Builder() to obtain handler instances.

Properties

Property	Type	Description
`BackingContainer`	`Container`	The underlying in-memory container (as SDK `Container`)
`RequestLog`	`IReadOnlyCollection<string>`	Recorded HTTP requests
`QueryLog`	`IReadOnlyCollection<string>`	Recorded SQL queries
`FaultInjector`	`Func<HttpRequestMessage, HttpResponseMessage?>?`	Fault injection delegate
`FaultInjectorIncludesMetadata`	`bool`	Whether faults affect metadata routes

Static Methods

Method	Returns	Description
`VerifySdkCompatibilityAsync()`	`Task`	SDK compatibility self-test

In-memory implementation of User.

Namespace: CosmosDB.InMemoryEmulator
Inherits: Microsoft.Azure.Cosmos.User
Sealed: Yes

Properties

Property	Type	Description
`Id`	`string`	User identifier

Methods

Method	Returns	Description
`ReadAsync(...)`	`UserResponse`	Read user properties
`ReplaceAsync(UserProperties, ...)`	`UserResponse`	Replace user properties
`DeleteAsync(...)`	`UserResponse`	Delete user
`GetPermission(string id)`	`Permission`	Get permission by id
`CreatePermissionAsync(PermissionProperties, int?, ...)`	`PermissionResponse`	Create permission (409 if exists)
`UpsertPermissionAsync(PermissionProperties, int?, ...)`	`PermissionResponse`	Create or replace permission
`GetPermissionQueryIterator<T>(string?, string?, QueryRequestOptions?)`	`FeedIterator<T>`	List permissions
`GetPermissionQueryIterator<T>(QueryDefinition?, string?, QueryRequestOptions?)`	`FeedIterator<T>`	List permissions by query

`InMemoryPermission`

In-memory implementation of Permission.

Namespace: CosmosDB.InMemoryEmulator
Inherits: Microsoft.Azure.Cosmos.Permission
Sealed: Yes

Properties

Property	Type	Description
`Id`	`string`	Permission identifier

Methods

Method	Returns	Description
`ReadAsync(int?, ...)`	`PermissionResponse`	Read permission properties
`ReplaceAsync(PermissionProperties, int?, ...)`	`PermissionResponse`	Replace permission properties
`DeleteAsync(...)`	`PermissionResponse`	Delete permission

`FakeCosmosHandlerOptions`

Configuration for FakeCosmosHandler.

Namespace: CosmosDB.InMemoryEmulator
Sealed: Yes

Property	Type	Default	Description
`CacheTtl`	`TimeSpan`	5 min	Query result cache TTL
`CacheMaxEntries`	`int`	100	Max cached query results
`PartitionKeyRangeCount`	`int`	1	Number of simulated partition ranges

`InMemoryFeedIterator<T>`

In-memory implementation of FeedIterator<T>.

Namespace: CosmosDB.InMemoryEmulator
Inherits: Microsoft.Azure.Cosmos.FeedIterator<T>

Constructors

InMemoryFeedIterator(IReadOnlyList<T> items, int? maxItemCount = null, int initialOffset = 0)
InMemoryFeedIterator(IEnumerable<T> source, int? maxItemCount = null)
InMemoryFeedIterator(Func<IReadOnlyList<T>> factory, int? maxItemCount = null)

`InMemoryTransactionalBatch`

In-memory implementation of TransactionalBatch. Supports CreateItem, UpsertItem, ReplaceItem, DeleteItem, ReadItem, PatchItem, and their stream variants. All operations execute atomically via ExecuteAsync.

Namespace: CosmosDB.InMemoryEmulator
Inherits: Microsoft.Azure.Cosmos.TransactionalBatch

Note: Internal class. Obtained via Container.CreateTransactionalBatch(partitionKey).

`InMemoryFeedIteratorSetup`

Deprecated. All recommended approaches now use FakeCosmosHandler, which handles .ToFeedIterator() natively. See How Does ToFeedIterator() Work? for details.

Namespace: CosmosDB.InMemoryEmulator

Method	Description
`Register()`	Enable in-memory feed iterator interception (legacy)
`Deregister()`	Disable interception, revert to SDK behaviour

`IJsTriggerEngine`

Interface for executing JavaScript trigger bodies. Implemented by JintTriggerEngine in the JsTriggers package, or provide a custom implementation.

Namespace: CosmosDB.InMemoryEmulator

Method	Returns	Description
`ExecutePreTrigger(string jsBody, JObject document)`	`JObject`	Execute pre-trigger, returns (possibly modified) document
`ExecutePreTrigger(string jsBody, JObject document, ICollectionContext context)`	`JObject`	Execute pre-trigger with collection CRUD access
`ExecutePostTrigger(string jsBody, JObject document)`	`JObject?`	Execute post-trigger
`ExecutePostTrigger(string jsBody, JObject document, ICollectionContext context)`	`JObject?`	Execute post-trigger with collection CRUD access

`IJsUdfEngine`

Interface for executing JavaScript UDF bodies. Implemented by JintTriggerEngine.

Namespace: CosmosDB.InMemoryEmulator

Method	Returns	Description
`ExecuteUdf(string jsBody, object[] args)`	`object?`	Execute a JavaScript UDF function body

`ICollectionContext`

Partition-scoped document CRUD operations for use inside JavaScript stored procedures and triggers.

Namespace: CosmosDB.InMemoryEmulator

Member	Returns	Description
`CreateDocument(JObject document)`	`JObject`	Insert a document
`ReadDocument(string id)`	`JObject`	Read a document by ID
`QueryDocuments(string sql)`	`IReadOnlyList<JObject>`	Execute SQL query within partition
`ReplaceDocument(string id, JObject document)`	`JObject`	Replace a document
`DeleteDocument(string id)`	`void`	Delete a document by ID
`SelfLink`	`string`	Collection self link

`ServiceCollectionExtensions`

DI extension methods for IServiceCollection. See the Setup Guide for usage examples.

Namespace: CosmosDB.InMemoryEmulator

Method	Description
`UseInMemoryCosmosDB(Action<InMemoryCosmosOptions>?)`	Replace `CosmosClient` + `Container` registrations using `FakeCosmosHandler`
`UseInMemoryCosmosContainers(Action<InMemoryContainerOptions>?)`	Replace `Container` registrations only
`UseInMemoryCosmosDB<TClient>(Action<InMemoryCosmosOptions>?)`	Replace typed `CosmosClient` subclass + `Container` registrations

`InMemoryCosmosOptions`

Options for UseInMemoryCosmosDB() and UseInMemoryCosmosDB<TClient>().

Namespace: CosmosDB.InMemoryEmulator

Property	Type	Default	Description
`Containers`	`List<ContainerConfig>`	Empty	Container configurations
`DatabaseName`	`string?`	`"in-memory-db"`	Default database name
`RegisterFeedIteratorSetup`	`bool`	`true`	Ignored — all DI methods now use `FakeCosmosHandler` which handles `.ToFeedIterator()` natively
`OnClientCreated`	`Action<CosmosClient>?`	null	Post-creation callback (receives real `CosmosClient` backed by `FakeCosmosHandler`, or a Castle.Core dynamic proxy for the `<TClient>` overload)
`OnHandlerCreated`	`Action<string, FakeCosmosHandler>?`	null	Per-container handler callback. Fires for all DI methods including `UseInMemoryCosmosDB<TClient>()`
`HttpMessageHandlerWrapper`	`Func<HttpMessageHandler, HttpMessageHandler>?`	null	Wraps the `FakeCosmosHandler`/router before it's passed to `HttpClientFactory`. Applies to all DI methods including `UseInMemoryCosmosDB<TClient>()`
`StatePersistenceDirectory`	`string?`	null	Directory for automatic state persistence. Container state is loaded on creation and saved on disposal. Files are named `{DatabaseName}_{ContainerName}.json`. See State Persistence
Method	Returns	Description
--------	---------	-------------
`AddContainer(string containerName, string partitionKeyPath = "/id", string? databaseName = null)`	`InMemoryCosmosOptions`	Fluent helper to add a container configuration
`WithHttpMessageHandlerWrapper(Func<HttpMessageHandler, HttpMessageHandler> wrapper)`	`InMemoryCosmosOptions`	Fluent helper to set `HttpMessageHandlerWrapper`

`InMemoryContainerOptions`

Options for UseInMemoryCosmosContainers().

Namespace: CosmosDB.InMemoryEmulator

Property	Type	Default	Description
`Containers`	`List<ContainerConfig>`	Empty	Container configurations
~~`RegisterFeedIteratorSetup`~~	`bool`	`true`	Obsolete. Ignored — `FakeCosmosHandler` handles `.ToFeedIterator()` natively
`OnContainerCreated`	`Action<IContainerTestSetup>?`	null	Per-container callback
`StatePersistenceDirectory`	`string?`	null	Directory for automatic state persistence. Container state is loaded on creation and saved on disposal. Files are named `{ContainerName}.json`. See State Persistence

Method	Returns	Description
`AddContainer(string containerName = "in-memory-container", string partitionKeyPath = "/id")`	`InMemoryContainerOptions`	Fluent helper to add a container configuration

`ContainerConfig`

public record ContainerConfig(
    string ContainerName,
    string PartitionKeyPath = "/id",
    string? DatabaseName = null);

`CosmosSqlParser`

Cosmos DB SQL parser (internal details exposed for advanced use).

Namespace: CosmosDB.InMemoryEmulator

Method	Returns	Description
`Parse(string sql)`	`CosmosSqlQuery`	Parse SQL (throws on failure)
`TryParse(string sql, out CosmosSqlQuery)`	`bool`	Parse SQL (returns false on failure)

Package: CosmosDB.InMemoryEmulator.ProductionExtensions

Deprecated. This package is no longer needed. All recommended approaches use FakeCosmosHandler, which handles .ToFeedIterator() natively. See How Does ToFeedIterator() Work? and What's New in 4.0 for details.

Package: CosmosDB.InMemoryEmulator.JsTriggers

Optional package that provides a Jint-based JavaScript engine for executing real Cosmos DB trigger scripts in tests.

`JintTriggerEngine`

JavaScript trigger engine built on Jint.

Namespace: CosmosDB.InMemoryEmulator.JsTriggers
Implements: IJsTriggerEngine, IJsUdfEngine

Method	Returns	Description
`ExecutePreTrigger(string jsBody, JObject document)`	`JObject`	Execute pre-trigger JavaScript, returns modified document
`ExecutePreTrigger(string jsBody, JObject document, ICollectionContext context)`	`JObject`	Execute pre-trigger with collection CRUD access
`ExecutePostTrigger(string jsBody, JObject document)`	`JObject?`	Execute post-trigger JavaScript
`ExecutePostTrigger(string jsBody, JObject document, ICollectionContext context)`	`JObject?`	Execute post-trigger with collection CRUD access
`ExecuteUdf(string jsBody, object[] args)`	`object?`	Execute JavaScript UDF body

`JintSprocEngine`

JavaScript stored procedure engine built on Jint.

Namespace: CosmosDB.InMemoryEmulator.JsTriggers
Implements: ISprocEngine

Method	Returns	Description
`Execute(string jsBody, PartitionKey pk, dynamic[] args)`	`string?`	Execute stored procedure without collection access
`Execute(string jsBody, PartitionKey pk, dynamic[] args, ICollectionContext ctx)`	`string?`	Execute stored procedure with partition-scoped collection CRUD
`CapturedLogs`	`IReadOnlyList<string>`	Console.log output from last execution

`JsTriggerExtensions`

Extension method to wire up the Jint engine.

Namespace: CosmosDB.InMemoryEmulator.JsTriggers

Method	Returns	Description
`UseJsTriggers(this IContainerTestSetup)`	`IContainerTestSetup`	Sets `JsTriggerEngine` to a `JintTriggerEngine` instance

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API Reference

Package: CosmosDB.InMemoryEmulator

InMemoryCosmos (Static)

InMemoryCosmosBuilder

InMemoryCosmosResult : IDisposable, IAsyncDisposable

InMemoryDatabaseResult

IContainerTestSetup

FakeCosmosHandler

Properties

Static Methods

Properties

Methods

InMemoryPermission

Properties

Methods

FakeCosmosHandlerOptions

InMemoryFeedIterator<T>

Constructors

InMemoryTransactionalBatch

InMemoryFeedIteratorSetup

IJsTriggerEngine

IJsUdfEngine

ICollectionContext

ServiceCollectionExtensions

InMemoryCosmosOptions

InMemoryContainerOptions

ContainerConfig

CosmosSqlParser

Package: CosmosDB.InMemoryEmulator.ProductionExtensions

Package: CosmosDB.InMemoryEmulator.JsTriggers

JintTriggerEngine

JintSprocEngine

JsTriggerExtensions

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Clone this wiki locally

`InMemoryCosmos` (Static)

`InMemoryCosmosBuilder`

`InMemoryCosmosResult` : `IDisposable`, `IAsyncDisposable`

`InMemoryDatabaseResult`

`IContainerTestSetup`

`FakeCosmosHandler`

`InMemoryPermission`

`FakeCosmosHandlerOptions`

`InMemoryFeedIterator<T>`

`InMemoryTransactionalBatch`

`InMemoryFeedIteratorSetup`

`IJsTriggerEngine`

`IJsUdfEngine`

`ICollectionContext`

`ServiceCollectionExtensions`

`InMemoryCosmosOptions`

`InMemoryContainerOptions`

`ContainerConfig`

`CosmosSqlParser`

`JintTriggerEngine`

`JintSprocEngine`

`JsTriggerExtensions`