Five types of Test doubles

• Dummy

  Mainly used to fill in parameter lists

• Fake

  A lightweight example of an object that the unit under test requires - e.g. inmemory DB

• Stub

  An object that only writes pre-programmed answers - naive implementation

• Spy

  Like a stub but with the capability to remember how it was called

• Mock

  Configured with expectations which are a description of the calls they expect to recieve during the test Only mocks insist in behaviour testing