Unit Testing with Mocks: Mocking Exceptions & Using Spies

Unlike a mock, which has no real state, and in which all behavior must be stubbed, a spy is built atop a real object of the class being mocked and has almost full functionality. Only specific methods of the spy are stubbed, which is useful if it is too complex or cumbersome to mock.

Use this course to learn how to identify when spies are a better choice than mocks, how to construct spies and stub specific methods, and how to raise exceptions in stubbed methods of your mocks. Then, use different methods to check how the object under test copes with those exceptions.

Moving on, learn how to stub void methods and when to make use of the doNothing().when() syntax.

When you're done, you'll be able to correctly use spies, mock exceptions and test their handling, mock void methods, and use argument captors.