An in-memory data store that speaks enough mongodb protocol to use in place of a live mongodb in your tests.

• Designed for testing applications that are hard-coded against the mgo driver.
• Implements enough of a subset of the mongodb protocol to fool mgo for most purposes.
• Easy to set up and tear down in unit tests.
• Can easily introspect or dump on contents after a test is run.

• Can connect with mongo command line client, mgo driver.
• mgo-based test cases.
• Simple-case CRUD is working for query, insert, update, delete.
• Some database and admin commands are supported.

• More complete coverage of query operators (comparison, other matching)
• Sub-document selector matching, modification
• findAndModify

• Cursors
• Auth commands
• TLS
• Indexes
• Capped collections
• Backend refactoring
• Moar backends (PostgreSQL JSONB, Cassandra, Riak, etc.)

• http://docs.mongodb.org/meta-driver/latest/legacy/mongodb-wire-protocol/

Other in-memory MongoDB protocol servers:

• https://github.com/bwaldvogel/mongo-java-server
• https://github.com/rick446/MongoTools/blob/master/mongotools/mim/mim.py