How to use createMockHandler method of org.mockito.internal.handler.MockHandlerFactory class

it is because of the version conflict between PowerMockito and Mockito artifacts. "MockCreationSettings.isUsingConstructor" method is removed in new versions, so you need to be sure you are using correct versions. e.g use PowerMockito version 1.6.2 with Mockito version 1.10.19 (this version has that missing method)

In new Mockito versions you can use stubbing consecutive calls to throw exception on first can and returning a value on a second call.

when(mock.someMethod("some arg"))
    .thenThrow(new RuntimeException())
    .thenReturn("foo");

https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html#10

UPDATE: My answer is quite old. There is a built-in method in Mockito now to insert the delay directly: AnswersWithDelay. See Bogdan's response for more details.

There is already a CallsRealMethods Answer that you can extend and decorate with your delay:

public class CallsRealMethodsWithDelay extends CallsRealMethods {

    private final long delay;

    public CallsRealMethodsWithDelay(long delay) {
        this.delay = delay;
    }

    public Object answer(InvocationOnMock invocation) throws Throwable {
        Thread.sleep(delay);
        return super.answer(invocation);
    }

}

And then use it like that:

MyObject foobar = Mockito.spy(new MyObject(param1, param2, param3));
Mockito.doAnswer(new CallsRealMethodsWithDelay(2000))
           .when(foobar).myRealMethodName();

You can of course also use a static method to make everything even more beautiful:

public static Stubber doAnswerWithRealMethodAndDelay(long delay) {
    return Mockito.doAnswer(new CallsRealMethodsWithDelay(delay));
}

And use it like:

doAnswerWithRealMethodAndDelay(2000)
           .when(foobar).myRealMethodName();

I found only two disadvantages in the field injection.

• Hard to inject mocks when the object is under test. (Can be resolved with @InjectMocks from Mockito)

• Circle dependencies. If bean A depends on bean B and bean B needs bean A. If you have the constructor injection it easy to find it.

Fail the test if an exception is caught.

@Test
public void testGetBalanceForPerson() {

   // creating mock person
   Person person1 = mock(Person.class);
   when(person1.getId()).thenReturn("mockedId");

   // calling method under test
   try {
      myClass.getBalanceForPerson(person1);
   } catch(Exception e) {
      fail("Should not have thrown any exception");
   }
}

I had this issue and my problem was that I was calling my method with any() instead of anyInt(). So I had:

doAnswer(...).with(myMockObject).thisFuncTakesAnInt(any())

and I had to change it to:

doAnswer(...).with(myMockObject).thisFuncTakesAnInt(anyInt())

I have no idea why that produced a NullPointerException. Maybe this will help the next poor soul.

There are different ways to use Mockito - I'll go through them one by one.

Manually

Creating mocks manually with Mockito::mock works regardless of the JUnit version (or test framework for that matter).

Annotation Based

Using the @Mock-annotation and the corresponding call to MockitoAnnotations::initMocks to create mocks works regardless of the JUnit version (or test framework for that matter but Java 9 could interfere here, depending on whether the test code ends up in a module or not).

Mockito Extension

JUnit 5 has a powerful extension model and Mockito recently published one under the group / artifact ID org.mockito : mockito-junit-jupiter.

You can apply the extension by adding @ExtendWith(MockitoExtension.class) to the test class and annotating mocked fields with @Mock. From MockitoExtension's JavaDoc:

@ExtendWith(MockitoExtension.class)
public class ExampleTest {

    @Mock
    private List list;

    @Test
    public void shouldDoSomething() {
        list.add(100);
    }

}

The MockitoExtension documentation describes other ways to instantiate mocks, for example with constructor injection (if you rpefer final fields in test classes).

No Rules, No Runners

JUnit 4 rules and runners don't work in JUnit 5, so the MockitoRule and the Mockito runner can not be used.

You need to do this.

when(userRepository.save(Mockito.any(User.class)))
                .thenAnswer(i -> i.getArguments()[0]);

And now you can obtain user which you pass as argument.

You can mock the template but it's better to mock the interface.

    Sender sender = new Sender();
    KafkaOperations template = mock(KafkaOperations.class);
    SettableListenableFuture<SendResult<String, String>> future = new SettableListenableFuture<>();
    when(template.send(anyString(), any(Message.class))).thenReturn(future);
    sender.setTemplate(template);
    sender.send(...);

    future.set(new SendResult<>(...));

    ...or...

    future.setException(...