How to use doQuery method of org.mockitousage.bugs.injection.ParentTestMockInjectionTest class

You should use thenReturn or doReturn when you know the return value at the time you mock a method call. This defined value is returned when you invoke the mocked method.

thenReturn(T value) Sets a return value to be returned when the method is called.

@Test
public void test_return() throws Exception {
    Dummy dummy = mock(Dummy.class);
    int returnValue = 5;

    // choose your preferred way
    when(dummy.stringLength("dummy")).thenReturn(returnValue);
    doReturn(returnValue).when(dummy).stringLength("dummy");
}

Answer is used when you need to do additional actions when a mocked method is invoked, e.g. when you need to compute the return value based on the parameters of this method call.

Use doAnswer() when you want to stub a void method with generic Answer.

Answer specifies an action that is executed and a return value that is returned when you interact with the mock.

@Test
public void test_answer() throws Exception {
    Dummy dummy = mock(Dummy.class);
    Answer<Integer> answer = new Answer<Integer>() {
        public Integer answer(InvocationOnMock invocation) throws Throwable {
            String string = invocation.getArgumentAt(0, String.class);
            return string.length() * 2;
        }
    };

    // choose your preferred way
    when(dummy.stringLength("dummy")).thenAnswer(answer);
    doAnswer(answer).when(dummy).stringLength("dummy");
}

Mockito itself doesn't seem to be able to mock native methods according to this Google Group thread. However you do have two options:

1. Wrap the TableElement class in an interface and mock that interface to properly test that your SUT calls the wrapped insertRow(...) method. The drawback is the extra interface that you need to add (when GWT project should've done this in their own API) and the overhead to use it. The code for the interface and the concrete implementation would look like this:

   // the mockable interface
   public interface ITableElementWrapper {
       public void insertRow(int index);
   }
   
   // the concrete implementation that you'll be using
   public class TableElementWrapper implements ITableElementWrapper {
       TableElement wrapped;
   
       public TableElementWrapper(TableElement te) {
           this.wrapped = te;
       }
   
       public void insertRow(int index) {
           wrapped.insertRow(index);
       }
   }
   
   // the factory that your SUT should be injected with and be 
   // using to wrap the table element with
   public interface IGwtWrapperFactory {
       public ITableElementWrapper wrap(TableElement te);
   }
   
   public class GwtWrapperFactory implements IGwtWrapperFactory {
       public ITableElementWrapper wrap(TableElement te) {
           return new TableElementWrapper(te);
       }
   }
   

2. Use Powermock and it's Mockito API extension called PowerMockito to mock the native method. The drawback is that you have another dependency to load into your test project (I'm aware this may be a problem with some organizations where a 3rd party library has to be audited first in order to be used).

Personally I'd go with option 2, as GWT project is not likely to wrap their own classes in interfaces (and it is more likely they have more native methods that needs to be mocked) and doing it for yourself to only wrap a native method call is just waste of your time.

Difference between a Spy and a Mock

When Mockito creates a mock – it does so from the Class of a Type, not from an actual instance. The mock simply creates a bare-bones shell instance of the Class, entirely instrumented to track interactions with it. On the other hand, the spy will wrap an existing instance. It will still behave in the same way as the normal instance – the only difference is that it will also be instrumented to track all the interactions with it.

In the following example – we create a mock of the ArrayList class:

@Test
public void whenCreateMock_thenCreated() {
    List mockedList = Mockito.mock(ArrayList.class);

    mockedList.add("one");
    Mockito.verify(mockedList).add("one");

    assertEquals(0, mockedList.size());
}

As you can see – adding an element into the mocked list doesn’t actually add anything – it just calls the method with no other side-effect. A spy on the other hand will behave differently – it will actually call the real implementation of the add method and add the element to the underlying list:

@Test
public void whenCreateSpy_thenCreate() {
    List spyList = Mockito.spy(new ArrayList());
    spyList.add("one");
    Mockito.verify(spyList).add("one");

    assertEquals(1, spyList.size());
}

Here we can surely say that the real internal method of the object was called because when you call the size() method you get the size as 1, but this size() method isn’t been mocked! So where does 1 come from? The internal real size() method is called as size() isn’t mocked (or stubbed) and hence we can say that the entry was added to the real object.

Source: http://www.baeldung.com/mockito-spy + self notes.

Cache.put is final, so you need to use PowerMock if you want to mock it.

Your test would look like this:

@RunWith(PowerMockRunner.class)
@PrepareForTest(Cache.class)
public class EhCacheBaseTest {
    private static final String CACHE_NAME = "testCache";
    private CacheManager cacheManager;
    private Cache cache;
    private EhCacheBase<String, Object> ehCacheBase;

    @Before
    public void init() {
        // You can statically import mock method, but left it this way 
        // for clarity
        cacheManager = PowerMockito.mock(CacheManager.class);
        cache = PowerMockito.mock(Cache.class);
        ehCacheBase = new EhCacheBase<String, Object>(CACHE_NAME);
        EhCacheBase.setCacheManager(cacheManager);
    }

    @Test
    public void shouldRetrieveCacheAndPutOneValueInIt() {
        //given
        Object o = new Object();
        when(cacheManager.getCache(CACHE_NAME)).thenReturn(cache);

        //when
        ehCacheBase.cache("KEY", o);

        //then
        verify(cacheManager, times(1)).getCache(CACHE_NAME);
        verify(cache, times(1)).put(any(Element.class));
    }
}

Use the doReturn-when alternate stubbing syntax.

System under test:

public class MyClass {
  Set<? extends Number> getSet() {
    return new HashSet<Integer>();
  }
}

and the test case:

import static org.mockito.Mockito.*;

import java.util.HashSet;
import java.util.Set;

import org.junit.Test;

public class TestMyClass {
  @Test
  public void testGetSet() {
    final MyClass mockInstance = mock(MyClass.class);

    final Set<Integer> resultSet = new HashSet<Integer>();
    resultSet.add(1);
    resultSet.add(2);
    resultSet.add(3);

    doReturn(resultSet).when(mockInstance).getSet();

    System.out.println(mockInstance.getSet());
  }
}

No errors or warning suppression needed

If I were you, I would simply mock the services A and B and your executors, then inject them thanks to the annotation @InjectMocks as they are fields of your class.

If you want mock the method execute of your Executor, you should rather proceed as next to simply call the method run of the provided Runnable:

doAnswer(
    (InvocationOnMock invocation) -> {
        ((Runnable) invocation.getArguments()[0]).run();
        return null;
    }
).when(serviceAExecutorService).execute(any(Runnable.class));

So basically your test would be something like this:

@RunWith(MockitoJUnitRunner.class)
public class CompletableFutureServiceTest {

    // The mock of my service A
    @Mock
    private ServiceA ServiceA;
    // The mock of my service B
    @Mock
    private ServiceB ServiceB;
    // The mock of your executor for the service A
    @Mock
    private Executor serviceAExecutorService;
    // The mock of your executor for the service B
    @Mock
    private Executor serviceBExecutorService;
    // My class in which I want to inject the mocks
    @InjectMocks
    private CompletableFutureService service;

    @Test
    public void testSomeMethod() {
        // Mock the method execute to call the run method of the provided Runnable
        doAnswer(
            (InvocationOnMock invocation) -> {
                ((Runnable) invocation.getArguments()[0]).run();
                return null;
            }
        ).when(serviceAExecutorService).execute(any(Runnable.class));
        doAnswer(
            (InvocationOnMock invocation) -> {
                ((Runnable) invocation.getArguments()[0]).run();
                return null;
            }
        ).when(serviceBExecutorService).execute(any(Runnable.class));

        ServiceAResponse serviceAResponse = ... // The answer to return by service A
        // Make the mock of my service A return my answer
        when(ServiceA.retrieve(any(ServiceARequest.class))).thenReturn(
            serviceAResponse
        );
        ServiceBResponse serviceBResponse = ... // The answer to return by service B
        // Make the mock of my service B return my answer
        when(ServiceB.retrieve(any(ServiceBRequest.class))).thenReturn(
            serviceBResponse
        );

        // Execute my method
        ServiceResponse response = service.someMethod(
            new ServiceARequest(), new ServiceBRequest()
        );

        // Test the result assuming that both responses are wrapped into a POJO
        Assert.assertEquals(serviceAResponse, response.getServiceAResponse());
        Assert.assertEquals(serviceBResponse, response.getServiceBResponse());
    }
}

You can use a spy on your static class and mock only specific methods:

@RunWith(PowerMockRunner.class)
@PrepareForTest(MyStaticTest.MyStaticClass.class)
public class MyStaticTest {

public static class MyStaticClass {
    public static String getA(String a) {
        return a;
    }
    public static String getB(String b) {
        return b;
    }
}

@Test
public void should_partial_mock_static_class() throws Exception {
    //given
    PowerMockito.spy(MyStaticClass.class);
    given(MyStaticClass.getB(Mockito.anyString())).willReturn("B");
    //then
    assertEquals("A", MyStaticClass.getA("A"));
    assertEquals("B", MyStaticClass.getA("B"));
    assertEquals("C", MyStaticClass.getA("C"));
    assertEquals("B", MyStaticClass.getB("A"));
    assertEquals("B", MyStaticClass.getB("B"));
    assertEquals("B", MyStaticClass.getB("C"));
}

}

You can implement this test functionality this way (Java 8):

myMock
    .expect(requestTo("http://myfakeurl.blabla"))
    .andExpect(method(HttpMethod.GET))
    .andRespond(request -> {
        try {
            Thread.sleep(TimeUnit.SECONDS.toMillis(1));
        } catch (InterruptedException ignored) {}
        return new MockClientHttpResponse(myJsonResponse, HttpStatus.OK);
    });

But, I should warn you, that since MockRestServiceServer simply replaces RestTemplate requestFactory any requestFactory settings you'd make will be lost in test environment.

You should avoid creating business objects with new in a Spring application. You should always get them from the application context - it will ease mocking them in your test.

In your use case, you should simply create your validator as a bean (say defaultTerminationValidator) and inject it in your controller :

public class TerminationController extends AbstractController {

    private TerminationValidator terminationValidator;

    @Autowired
    public setDefaultTerminationValidator(TerminationValidator validator) {
        this.terminationValidator = validator;
    }

    @InitBinder("termination")
    public void initBinder(WebDataBinder binder, HttpServletRequest request) {
        binder.setValidator(terminationValidator);
        binder.setAllowedFields(new String[] { "termId[**]", "terminationDate",
                "accountSelection", "iban", "bic" });
    }

    [...]
}

That way, you will be able to simply inject a mock in your test.