Mocha is a library for mocking and stubbing using a syntax like that of JMock, and SchMock. Most commonly Mocha is used in conjunction with Test::Unit, but it can be used in other contexts.

One of its main advantages is that it allows you to mock and stub methods on real (non-mock) classes and instances. You can for example stub ActiveRecord instance methods like create, save, destroy and even class methods like find to avoid hitting the database in unit tests.

Mocha provides a unified, simple and readable syntax for both traditional mocking and for mocking with real objects.

Mocha has been harvested from projects at Reevoo by me (James) and my colleagues Ben, Chris and Paul. Mocha is in use on real-world Rails projects.