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

Adding to what @sateesh said, when you just want to mock a void method in order to prevent the test from calling it, you could use a Spy this way:

World world = new World();
World spy = Mockito.spy(world);
Mockito.doNothing().when(spy).methodToMock();

When you want to run your test, make sure you call the method in test on the spy object and not on the world object. For example:

assertEquals(0, spy.methodToTestThatShouldReturnZero());