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Question

I have a JUnit test as:

@Spy
ParallelSender parallelSender = new ParallelSender();


@Test
public void send() {   
    // making some data...
    parallelSender.send(someData);
    // check that internal method has been called with Sender Task made from someData
    verify(parallelSender).doSend(any(SenderTask.class));
}

I however like to examine that SenderTask contains all the fields exactly as I need them. Can I tell the spy to intercept the doSend call, store its parameters in some array and then continue to real method?

Answer 1

Use the ArgumentCaptor:

@Test
public void send() {   
    // making some data...
    parallelSender.send(someData);

   // Define the captor for class
    ArgumentCaptor<SenderTask> captor =
        ArgumentCaptor.forClass(SenderTask.class);

    // Capture input while verifying
    verify(parallelSender).doSend(captor.capture());

    // Assert 
    SomeTask result = captor.getValue();
    // assertions on result
}