How to use IOOBExceptionShouldNotBeThrownWhenNotCodingFluentlyTest class of org.mockitousage.bugs package

You can mock without usage of the PowerMock it but in a slightly more complicated way:

KeyStoreSpi keyStoreSpiMock = mock(KeyStoreSpi.class);
KeyStore keyStoreMock = new KeyStore(keyStoreSpiMock, null, "test"){ };
keyStoreMock.load(null);  // this is important to put the internal state "initialized" to true

From now you just mock keyStoreSpiMock, for example:

when(keyStoreSpiMock.engineGetKey(any(), any())).thenReturn(mock(Key.class);

To to this, you can use PowerMockito.spy(...) and PowerMockito.doReturn(...).

Moreover, you have to specify the PowerMock runner at your test class, and prepare the class for testing, as follows:

@PrepareForTest(Util.class)
@RunWith(PowerMockRunner.class)
public class UtilTest {

   @Test
   public void testMethod() throws Exception {
      PowerMockito.spy(Util.class);
      PowerMockito.doReturn("abc").when(Util.class, "anotherMethod");

      String retrieved = Util.method();

      Assert.assertNotNull(retrieved);
      Assert.assertEquals(retrieved, "abc");
   }
}

Hope it helps you.

You have 3 possibilities to solve this:

Abstract factory: Instead of using a static method, use a concrete factory class:

public abstract class AppleFactory {
    public Apple createInstance(final String str);
}

public class AppleFactoryImpl implements AppleFactory {
    public Apple createInstance(final String str) { // Implementation }
}

In your test class, mock the factory:

@RunWith(MockitoJUnitRunner.class)
public class MyClassTest {

    @Mock
    private AppleFactory appleFactoryMock;

    @Mock
    private Apple appleMock;

    @InjectMocks 
    MyClass myClass;

    @Before
    public void setup() {
        when(appleFactoryMock.createInstance(Matchers.anyString()).thenReturn(appleMock);
    }

    @Test
    public void myMethod(){
     ...
     ...
     ...
    }
}

PowerMock: Use PowerMock to create a mock of a static method. Look at my answer to a relevant question to see how it's done.

Testable class: Make the Apple creation wrapped in a protected method and create a test class that overrides it:

public class MyClass {
   private Apple apple;

   public void myMethod() {
       apple = createApple();
       ....
       ....
       ....
   }

   protected Apple createApple() {
       return AppleFactory.createInstance(someStringVariable);
   }
}


@RunWith(MockitoJUnitRunner.class)
public class MyClassTest {

    @Mock
    private Apple appleMock;

    @InjectMocks 
    MyClass myClass;

    @Test
    public void myMethod(){
     ...
     ...
     ...
    }

    private class TestableMyClass extends MyClass {
       @Override
       public void createApple() {
          return appleMock;
       }
    }
}

Of course, in your test class you should test TestableMyClass and not MyClass.

I'll tell you my opinion on each of the methods:

1. The abstract factory method is the best one - This is a clear design that hides the implementation details

2. The testable class - Is the second option which requires minimum changes

3. The PowerMock option is my least favorite - Instead of going for a better design, you ignore and hide your problem. But that's still a valid option.

It is very likely that the Runnable hasn't been executed yet by the asyncTaskExecutor when you verify the invocation, resulting in a verification error in your unit test.

The best way to fix this is to join on the generated thread and wait for execution before verifying the invocations.

If you cannot get the instance of the thread, a possible work around is to mock the asyncTaskExecutor and implement it so it will execute the runnable directly.

private ExecutorService executor;

@Before
public void setup() {
    executor = mock(ExecutorService.class);
    implementAsDirectExecutor(executor);
}

protected void implementAsDirectExecutor(ExecutorService executor) {
    doAnswer(new Answer<Object>() {
        public Object answer(InvocationOnMock invocation) throws Exception {
            ((Runnable) invocation.getArguments()[0]).run();
            return null;
        }
    }).when(executor).submit(any(Runnable.class));
}

Mocks that return have the expectation that the return type matches the mocked object's return type.

Here's the mistake:

Mockito.when(remoteStore.get("a", "b")).thenReturn("lol");

"lol" isn't an Optional<String>, so it won't accept that as a valid return value.

The reason it worked when you did

Optional<Object> returnCacheValue = Optional.of((Object) returnCacheValueString);
Mockito.<Optional<Object>>when(remotestore.get("cache-name", "cache-key")).thenReturn(returnCacheValue);

is due to returnCacheValue being an Optional.

This is easy to fix: just change it to an Optional.of("lol") instead.

Mockito.when(remoteStore.get("a", "b")).thenReturn(Optional.of("lol"));

You can also do away with the type witnesses as well. The result above will be inferred to be Optional<String>.

The two syntaxes for stubbing are roughly equivalent. However, you can always use doReturn/when for stubbing; but there are cases where you can't use when/thenReturn. Stubbing void methods is one such. Others include use with Mockito spies, and stubbing the same method more than once.

One thing that when/thenReturn gives you, that doReturn/when doesn't, is type-checking of the value that you're returning, at compile time. However, I believe this is of almost no value - if you've got the type wrong, you'll find out as soon as you run your test.

I strongly recommend only using doReturn/when. There is no point in learning two syntaxes when one will do.

You may wish to refer to my answer at Forming Mockito "grammars" - a more detailed answer to a very closely related question.

The method you are mocking is not accessible to the Mockito code.

Because your test code and your code under test are in the same package, the compiler lets you set up your mock that way, but at runtime, the Mockito library has to try to access moveAttachment, but it's not working in your case. This appears to be a bug or known limitation in Mockito as it should support that case, (and in fact, does support it in most cases).

The easiest thing to do would be to make moveAttachment a public method. If that is not an option, then first question whether you want to even mock it. What happens if the real method gets called?

The last option is to use PowerMock to treat the moveAttachment method as a private method and mock it that way.

I think the answer is no -- perhaps you could pull it off with some intense reflection wrangling, but if so I don't think it would be worth your time.

But I think (without seeing your method), you can probably still get full coverage on your method:

• If your method takes any action after catching the exception, assert or verify that those actions happened.
  
  
• If no action happens after catching the exception, assert or verify that whatever actions were supposed to happen but were cut off by the exception, didn't happen.
  
  
• Finally, (again, not seeing your method I don't know exactly what you're dealing with) if your method is void, and nothing happens after catching the exception, and the last line of logic is what can throw the exception, then consider making your method return a boolean, have it return false if the exception is caught and true otherwise. Then in your test, make a scenario that should cause the exception to be thrown and caught, and test that the method returns false.
  
  

You have it right the second way:

verify(mock).someMethod(sampleCaptor.capture(), Matchers.eq(false));

When using Matchers (including ArgumentCaptor.capture), you have to use a Matcher for every value, because Matchers work via side-effects.

If the above doesn't work, you may be misusing matchers earlier in the method. It is sometimes helpful to explicitly call Mockito.validateMockitoUsage() immediately before your call to verify, to ensure that there's nothing wrong with Mockito's internal state. (Additional information about how it "does not work", including a minimal reproducible example, may be helpful in solving your specific case.)