How to use OngoingMockInjection method of org.mockito.internal.configuration.injection.MockInjection class

You are using the @InjectMocks for constructor incjection. This will work as long as Mockito finds the field not initalized (null). JUnit is creating a new instance of the test class before each test, so JUnit fans (like me) will never face such problem. TestNg is not creating a new instance of test class. It's keeping the state between test methods, so when MockitoAnnotations.initMocks(this) is called for the second time, Mockito will find subject field already initialized and will try to use field injection. This on the other turn will work until the field is not final.

Is this is a bug? I believe not - rather a natural consequence of the API design. Some workaround for you would be to add

this.subject = null;

in some @AfterMethod method.

You could simply put the thread to sleep for the desired time. Watch out tho - such things can really slow down your automated test execution, so you might want to isolate such tests in a separate suite

It would look similar to this:

when(mock.load("a")).thenAnswer(new Answer<String>() {
   @Override
   public String answer(InvocationOnMock invocation){
     Thread.sleep(5000);
     return "ABCD1234";
   }
});

Use @Spy annotation

@RunWith(MockitoJUnitRunner.class)
public class DemoTest {
    @Spy
    private SomeService service = new RealServiceImpl();

    @InjectMocks
    private Demo demo;

    /* ... */
}

Mockito will consider all fields having @Mock or @Spy annotation as potential candidates to be injected into the instance annotated with @InjectMocks annotation. In the above case 'RealServiceImpl' instance will get injected into the 'demo'

For more details refer

Mockito-home

@Spy

@Mock

Alright, I figured it out thanks to Stefan Birkner's reference

Here is the correction to my sample code:

import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Test1.class)
public class PowerMockTest {
    @Test
    public void staticVerifyTest() {
        PowerMockito.mockStatic(Test1.class);
        // Test
        Test1.staticMethod();
        PowerMockito.verifyStatic();
        Test1.staticMethod();
    }
}

After the static method is invoked, you need to verify that it was called by calling it again after your verifyStatic() call.

i.e.

        Test1.staticMethod();
        PowerMockito.verifyStatic();
        Test1.staticMethod();

You can also check if it was called multiple times like this...

Test1.staticMethod();
Test1.staticMethod();
Test1.staticMethod();
PowerMockito.verifyStatic(Mockito.times(3));
Test1.staticMethod();

Some of the other answers offer alternatives to doing exactly what I want here, but this is doable by Spying the Consumer class itself and having the spy call the method you really want to execute. A helper method for wrapping the lambda to create the spy helps here:

/** Get a spied version of the given Consumer. */
private Consumer<Item> itemHandlerSpy(Consumer<Item> itemHandler) {
  // Create a spy of the Consumer functional interface itself.
  @SuppressWarnings("unchecked")
  Consumer<Item> spy = (Consumer<Item>) Mockito.spy(Consumer.class);
  // Tell the spy to run the given consumer when the Consumer is given something to consume. 
  Mockito.doAnswer(it -> {
    // Get the first (and only) argument passed to the Consumer.
    Item item = (Item) it.getArguments()[0];
    // Pass it to the real consumer so it gets processed.
    itemHandler.accept(item);
    return null;
  }).when(spy).accept(Mockito.any(Item.class));
  return spy;
}

And then the test method becomes very straightforward:

Consumer<Item> itemHandler = itemHandlerSpy(Item::foo);
instance.conditionalRun(itemHandler);
// This verifies conditionalRun called the Consumer exactly once.
Mockito.verify(itemHandler).accept(Mockito.any(Item.class));

I would strongly suggest that you avoid using System.currentTimeMillis (and new Date() etc) in your general code.

Instead, create a Clock interface representing "a service to give you the current time" and then create one implementation which does use System.currentTimeMillis or whatever, and a fake implementation that you can control explicitly.

Use dependency injection to make an instance of this service available to code which needs it. In production, use the System.currentTimeMillis version, and in testing use your fake.

This gives you the ability not just to stop time, but to set it to whatever you want - so you can have static test data which you know will never expire, and you can easily test tricky things around boundaries etc. I've used this approach very successfully in many projects, to the extent that in my Noda Time project it's the way of getting at "the current time".

Note that if you're doing any serious amount of time work in Java, I'd recommend using Joda Time, and making your Clock interface return an Instant:

public interface Clock {
    Instant now();
}

With mockito 2.x, JDK 8 default methods are supported.

With mockito 1.x it's not possible,

Old answer

Unfortunately it's not yet possible (mockito 1.10.19), from the README.md on the github'page

JDK8 status

Mockito should work fine with JDK8 if you stay away from default methods (aka defender methods). Lambda usage may work just as good for Answers. We're unsure about every JDK8 features at the moment, like serializing a mock that uses a lambda. Error report and pull request are welcome though (contributing guide).

EDIT 1: defender methods and default methods are different names for the same thing.

I hope for a mockmaker replacement that will handle java 8 opcodes properly for such cases as some opcodes have a different semantic in Java 8.

EDIT 2: Updated the mockito readme, and this quote accordingly

retryWhen() won't call repository.getObservable() a second time. Instead, it takes the Observable.error() that was returned the first time and resubscribes to it.

In order to use retryWhen() in this way, you'd have to return a single Observable that returns an error the first time it's subscribed to and does not do so in subsequent subscriptions. For example, you could do something like this:

Observable.defer(new Func0<Observable<String>>() {
  boolean hasBeenSubscribedTo = false;

  @Override public Observable<String> call() {
    if (!hasBeenSubscribedTo) {
      hasBeenSubscribedTo = true;
      return Observable.error(new Exception());
    }
    return Observable.just("Hello, world!");
  }
})
.retryWhen(/* ...etc... */)

They both achieve the same result. Using an annotation (@Mock) is usually considered "cleaner", as you don't fill up your code with boilerplate assignments that all look the same.

Note that in order to use the @Mock annotation, your test class should be annotated with @RunWith(MockitoJUnitRunner.class) or contain a call to MockitoAnnotations.initMocks(this) in its @Before method.