Mockito and JUnit issue - junit

Question

I have this test:
#Test
public void shouldReturn2Hours() {
Float expectedHours = 2f;
WorkChronometer workChronometer = Mockito.mock(WorkChronometer.class);
Mockito.when(workChronometer.getAccumulatedMinutes()).thenReturn(120);
Assert.assertEquals(expectedHours, workChronometer.getAccumulatedHours());
}
and the implementation of WorkChronometer:
public class WorkChronometer {
private DateTime startingInstant;
private DateTime stoppingInstant;
private Boolean counting;
//More methods
public Integer getAccumulatedMinutes() {
if (counting)
throw new RuntimeException("Call stopCount first!");
if (startingInstant == null || stoppingInstant == null)
return 0;
return Minutes.minutesBetween(startingInstant, stoppingInstant).getMinutes();
}
public Float getAccumulatedHours() {
Integer accumulatedMinutes = getAccumulatedMinutes();
return accumulatedMinutes / 60f;
}
}
When I execute the test, it fails:
junit.framework.AssertionFailedError: expected:<2.0> but was:<0.0>
But I don't know why. It seems the mock is not returning what I want.
What am I doing wrong?
Thanks.

Answer 1

You're mocking the class under test. Doing that relaces all the methods by methods doing nothing, and returning default values.
If you want to do that, you'll need a spy, or a partial mock.
With a spy:
#Test
public void shouldReturn2Hours() {
Float expectedHours = 2f;
WorkChronometer workChronometer = new WorkChronometer();
WorkChronometer spy = Mockito.spy(workChronometer);
doReturn(120).when(spy).getAccumulatedMinutes();
Assert.assertEquals(expectedHours, spy.getAccumulatedHours());
}
With a partial mock:
#Test
public void shouldReturn2Hours() {
Float expectedHours = 2f;
WorkChronometer workChronometer = Mockito.mock(WorkChronometer.class);
Mockito.when(workChronometer.getAccumulatedHours()).thenCallRealMethod();
Mockito.when(workChronometer.getAccumulatedMinutes()).thenReturn(120);
Assert.assertEquals(expectedHours, workChronometer.getAccumulatedHours());
}