JMock triggers AssertionError: invokation expected once, never invoked - but it has been invoked

Question

I'm pretty new to programming with java but I've tried to directly start with unit-testing and therefore also used JMock. I have already implemented some test-cases (with JMock) that work, but this one I just can't get to run.

What I did: I wrote a test-class which creates a mock object and then I'm expectation one (using oneOf) invocation. After running the unit test it says it fails (but the logs say otherwise, as i print out the data I returned at the invocation using will(returnValue(x)).

The next funny/weird thing is - if I change the oneOf to "never" the unit test succeeds, but it throws an Exception:

Exception in thread "Thread-2" java.lang.AssertionError: unexpected invocation: blockingQueue.take()

expectations: expected never, never invoked: blockingQueue.take(); returns what happened before this: nothing!

Here the code:

@RunWith(JMock.class)
public class ExecuteGameRunnableTest {
    private Mockery context = new JUnit4Mockery();
    private Thread testObject;
    private BlockingQueue<Game> queueMock;
    private Executor executorMock;

    @SuppressWarnings("unchecked")
    @Before
    public void setUp() {
        queueMock = context.mock(BlockingQueue.class);
        executorMock = context.mock(Executor.class);
        testObject = new Thread(new ExecuteGameRunnable(queueMock, executorMock, true));
    }

    @After
    public void tearDown() {
        queueMock = null;
        executorMock = null;
        testObject = null;
    }

    @Test
    public void testQueueTake() throws InterruptedException {
        final Game game = new Game();
        game.setId(1);
        game.setProcessing(false);
        context.checking(new Expectations() {{
            never(queueMock).take(); will(returnValue(game));
        }});
        testObject.start();
        context.assertIsSatisfied();
    }
}

and the runnable that I'm testing:

public class ExecuteGameRunnable implements Runnable {
    private BlockingQueue<Game> queue;
    private Executor executor;
    private Boolean unitTesting = false;
    static Logger logger = Logger.getLogger(ExecuteGameRunnable.class);

    public ExecuteGameRunnable(BlockingQueue<Game> queue, Executor executor) {
        this.queue = queue;
        this.executor = executor;
    }

    public ExecuteGameRunnable (BlockingQueue<Game> queue, Executor executor, Boolean unitTesting) {
        this(queue,executor);
        this.unitTesting = unitTesting;
    }

    public void run() {
        try {
            do {
                if (Thread.interrupted()) throw new InterruptedException();
                Game game = queue.take();
                logger.info("Game "+game.getId()+" taken. Checking if it is processing"); // THIS ONE PRINTS OUT THE GAME ID THAT I RETURN WITH JMOCK-FRAMEWORK
                if (game.isProcessing()) {
                    continue;
                }
                game.updateProcessing(true);

                executor.execute(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub

                    }
                });
            } while (!unitTesting);
        } catch (InterruptedException ex) {
            logger.info("Game-Execution-Executor interrupted.");
            return;
        } catch (DataSourceException ex) {
            logger.fatal("Unable to connect to DB whilst executing game: "+id_game,ex);
            return;
        }
    }
}

strange, I got it running right now using: jmock.org/threading-executor.html — daskleinesys

Steve Freeman Steve Freeman · Accepted Answer · 2012-01-24T09:55:05

JMock isn't thread safe. It's intended to support unit testing, rather than what is a very small integration test. Frankly, in this case I'd use a real BlockingQueue rather than a mock one. And there is no way you should have a unitTesting flag in your production code.

One more thing, you don't need to set the fields in the test class to null, jUnit flushes the instance for every test.

JMock triggers AssertionError: invokation expected once, never invoked - but it has been invoked

1 Answers