API Reference

API Reference

Core Classes

InMemoryMongo

Static factory for creating in-memory MongoDB instances.

Method	Returns	Description
Create<T>(collectionName)	InMemoryMongoResult<T>	Creates a single-collection setup
Builder()	InMemoryMongoBuilder	Creates a multi-database builder

InMemoryMongoResult<T>

Property	Type	Description
Client	IMongoClient	The in-memory client
Database	IMongoDatabase	The in-memory database
Collection	IMongoCollection<T>	The in-memory collection

InMemoryMongoBuilder

Method	Returns	Description
AddDatabase(name, configure)	InMemoryMongoBuilder	Add a database with collections
Build()	IMongoClient	Build the multi-database setup

DatabaseBuilder

Method	Returns	Description
AddCollection<T>(name)	DatabaseBuilder	Add a typed collection

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InMemoryMongoClient : IMongoClient

Method	Description
GetDatabase(name)	Get or create an in-memory database
ListDatabases()	List all databases
ListDatabaseNames()	List all database names
DropDatabase(name)	Drop a database
StartSession()	Start a client session (transactions)
Watch()	Open a client-level change stream
WithReadConcern() / WithWriteConcern() / WithReadPreference()	Return configured client (settings stored, not enforced)
Dispose()	No-op. IMongoClient extends IDisposable in Driver 3.x

InMemoryMongoDatabase : IMongoDatabase

Method	Description
GetCollection<T>(name)	Get or create a collection
CreateCollection(name, options)	Create a collection (capped, validation, time series)
DropCollection(name)	Drop a collection
ListCollections()	List all collections
ListCollectionNames()	List collection names
RenameCollection(old, new)	Rename a collection
RunCommand<T>(command)	Execute a database command
Aggregate<T>(pipeline)	Database-level aggregation
CreateView(viewName, source, pipeline)	Create a view
Watch()	Open a database-level change stream
ExportState() / ImportState(json)	Export/import all collection data as JSON
ExportStateToFile(path) / ImportStateFromFile(path)	File-based export/import
ClearDocuments()	Clear all documents from all collections

InMemoryMongoCollection<T> : IMongoCollection<T>

CRUD

Method	Description
InsertOne / InsertOneAsync	Insert a single document
InsertMany / InsertManyAsync	Insert multiple documents
Find / FindSync / FindAsync	Query documents
UpdateOne / UpdateOneAsync	Update first matching document
UpdateMany / UpdateManyAsync	Update all matching documents
ReplaceOne / ReplaceOneAsync	Replace first matching document
DeleteOne / DeleteOneAsync	Delete first matching document
DeleteMany / DeleteManyAsync	Delete all matching documents
FindOneAndDelete / FindOneAndReplace / FindOneAndUpdate	Atomic find-and-modify
BulkWrite / BulkWriteAsync	Execute multiple write operations
CountDocuments / EstimatedDocumentCount	Count documents
Distinct / DistinctMany	Get distinct field values

Aggregation

Method	Description
Aggregate / AggregateAsync	Execute aggregation pipeline
AggregateToCollection	Execute pipeline, write results to collection

Change Streams

Method	Description
Watch / WatchAsync	Open a change stream on this collection

Indexes

Property	Description
Indexes	IMongoIndexManager<T> - create, drop, list indexes

Testing Utilities

Property	Type	Description
FaultInjector	Action<string, BsonDocument?>?	Hook to simulate failures
OperationLog	OperationLog	Records all operations for test assertions

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InMemoryGridFSBucket

Method	Description
UploadFromBytes / UploadFromBytesAsync	Upload file from byte array
UploadFromStream / UploadFromStreamAsync	Upload file from stream
DownloadAsBytes / DownloadAsBytesAsync	Download file as byte array
DownloadToStream / DownloadToStreamAsync	Download file to stream
DownloadAsBytesByName / DownloadToStreamByName	Download by filename
Delete / DeleteAsync	Delete a file
Rename / RenameAsync	Rename a file
Find / FindAsync	Find files by filter
Drop / DropAsync	Drop the entire bucket

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OperationLog

Method	Description
GetAll()	Get all recorded operations
GetByType(type)	Get operations by type (e.g., "InsertOne")
Clear()	Clear all recorded operations
Count	Number of recorded operations

OperationRecord

Property	Type	Description
Type	string	Operation type (e.g., "InsertOne", "UpdateOne")
Filter	BsonDocument?	The filter used
Update	BsonDocument?	The update document
Document	BsonDocument?	The document involved
Pipeline	BsonDocument[]?	The pipeline stages
Timestamp	DateTimeOffset	When the operation occurred

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DI Extension Methods

ServiceCollectionExtensions

Method	Description
UseInMemoryMongoDB(options)	Replace IMongoClient + IMongoDatabase + IMongoCollection
UseInMemoryMongoCollections(options)	Replace only IMongoCollection registrations

See Also

• Features — Feature reference
• Setup Guide — DI patterns