How to use DefaultAnswerValidator class of org.mockito.internal.stubbing.answers package

I wonder why you want to test, what method your method under tests invoke. Sounds pretty much like whitebox testing to me.

In my opinion, you want to verify the outcome of the invocation and not the way to get there, as this might easily change (i.e. when refactoring).

So if the outcome of doSecond() is the same as doFirst() you could write a test for doFirst() and use the same test (i.e. set of assertions) for testing doSecond().

But if you really want to test, whether doFirst() has been invoked by doSecond() you could wrap your service in a spy and then call the verification on the spy:

//given
SomeService service = new SomeService();
SomeService spy = Mockito.spy(service);
//when
spy.doSecond();
//then
verify(spy).doFirst();

You need to define the behavior for getPath() for folder as it gets called internally in File class.

You can do it as:

File folder = Mockito.mock(File.class);
when(folder.getPath()).thenReturn("C:\temp\");
File file = new Agent().createNewFile(folder, "fileName");

It will work only till you don't really create a new file but only calling new File.

You probably want to populate a normal list with your mocked objects. E.g.

List<User> mockList = new ArrayList<>();

User mockUser1 = Mockito.mock(User.class);
// ...    

mockList.add(mockUser1);
// etc.

Note that by default, Mockito returns an empty collection for any mocked methods that returns a collection. So if you just want to return an empty list, Mockito will already do that for you.

I had a similar issue and it was suggested to me to create a Resources.java class that Produced an Entity Manager.

@Stateful
public class Resources implements Serializable {

    @PersistenceContext (type = PersistenceContextType.TRANSACTION)
    private EntityManager entityManager;

    @Produces
    public EntityManager getEntityManager() {
        return entityManager;
    }

}

I'm still not exactly sure why this solution worked for me... but it did.

v/r Ace

Update July 29, 2015 by @durron597: This excellent answer was correct in 2013, however it has since been rendered obsolete by an update to Mockito. See this answer.

I use latest JUnit with Mockito core dependency and hamcrest 1.3 in many Maven projects at work. Till now nobody reported any problem with this. So if this works for your tests go with the newest Version for all three. Just ensure to use mockito core instead of all.

So I would recommend to go with option 2 to have all benefits of the newer versions. If you are really in doubt that anything could go wrong use option 4 which is the safest one. But of course you could go with option 2 and when in the near future anything would be wrong you could switch to option 2. Or since then a newer mockito is already out there solving this.

Note from mockito Issue 397: This problem does not appear with mockito-core.

Using Mockito, you can do spying on real objects like this:

import org.junit.Test;
import static org.mockito.Mockito.*;
public class MyClassTest {
    @Test
    public void otherMethodShouldBeCalled() {
        MyClass myClass = new MyClass();
        MyClass spy = spy(myClass);

        spy.myMethod(true);
        verify(spy).otherMethod();
    }
}

There are some gotchas, so take a look at the relevant documentation as well.

Powermock 1.6.3 uses javassist 3.15.2-GA which does not support certain types. Using 3.18.2-GA javassist worked for me. You may want to override dependency in your project.

    <dependency>
        <groupId>org.javassist</groupId>
        <artifactId>javassist</artifactId>
        <version>3.18.2-GA</version>
    </dependency>

You may face another problem for which the solution lies here Mockito + PowerMock LinkageError while mocking system class

Hope this helps.

To answer your second question first. If you're using JUnit 4, you can annotate your test with

@Test(expected=MyException.class)

to assert that an exception has occured. And to "mock" an exception with mockito, use

when(myMock.doSomething()).thenThrow(new MyException());

This code works fine. To set static field you need to pass a class to org.powermock.reflect.Whitebox.setInternalState. Please, ensure that you use PowerMock's class from the package org.powermock.reflect because Mockito has the class with the same name.

 @RunWith(PowerMockRunner.class)
 public class UtilitiesTest {

    @Mock
    private Logger.ALogger aLogger;

    @Before
    public void setUp() throws Exception {

        MockitoAnnotations.initMocks(this); // for case them used another runner
        Whitebox.setInternalState(CcpProcessorUtilities.class, "LOGGER", aLogger);
    }

    @Test
    public void testLogger() throws Exception {
        Utilities.convertToURl("");
        verify(aLogger).error(eq("Invalid Format"), any(IllegalArgumentException.class));
    }
}