How to mock void methods with Mockito

Question

How to mock methods with void return type?

I implemented an observer pattern but I can\'t mock it with Mockito because I don\'t know how.

And I tried to fin

Answer 1

First of all: you should always import mockito static, this way the code will be much more readable (and intuitive):

import static org.mockito.Mockito.*;

For partial mocking and still keeping original functionality on the rest mockito offers "Spy".

You can use it as follows:

private World world = spy(new World());

To eliminate a method from being executed you could use something like this:

doNothing().when(someObject).someMethod(anyObject());

to give some custom behaviour to a method use "when" with an "thenReturn":

doReturn("something").when(this.world).someMethod(anyObject());

For more examples please find the excellent mockito samples in the doc.