A final step for full OP_MSG support is to teach our mock server to speak the protocol. The existing OP_QUERY support in the mock server is very limited, because the implementation was copied from the driver in pieces. There are a few pieces required to realize this dream:

• Decouple Connection from the Pool by not passing in a messageHandler to the constructor, but use a message event instead
• Move the "connect" logic for creating and initially connection connections out of Connection into its own method, a la net.connect