How to tell a Mockito mock object to return something different the next time it is called?

You could also Stub Consecutive Calls (#10 in 2.8.9 api). In this case, you would use multiple thenReturn calls or one thenReturn call with multiple parameters (varargs).

import static org.junit.Assert.assertEquals;import static org.mockito.Mockito.mock;import static org.mockito.Mockito.when;import org.junit.Before;import org.junit.Test;public class TestClass {    private Foo mockFoo;    @Before    public void setup() {        setupFoo();    }    @Test    public void testFoo() {        TestObject testObj = new TestObject(mockFoo);        assertEquals(0, testObj.bar());        assertEquals(1, testObj.bar());        assertEquals(-1, testObj.bar());        assertEquals(-1, testObj.bar());    }    private void setupFoo() {        mockFoo = mock(Foo.class);        when(mockFoo.someMethod())            .thenReturn(0)            .thenReturn(1)            .thenReturn(-1); //any subsequent call will return -1        // Or a bit shorter with varargs:        when(mockFoo.someMethod())            .thenReturn(0, 1, -1); //any subsequent call will return -1    }}

For all who search to return something and then for another call throw exception:

when(mockFoo.someMethod())        .thenReturn(obj1)        .thenReturn(obj2)        .thenThrow(new RuntimeException("Fail"));

or

when(mockFoo.someMethod())        .thenReturn(obj1, obj2)        .thenThrow(new RuntimeException("Fail"));

First of all don't make the mock static. Make it a private field. Just put your setUp class in the @Before not @BeforeClass. It might be run a bunch, but it's cheap.

Secondly, the way you have it right now is the correct way to get a mock to return something different depending on the test.