How to mock DefaultMessageListenerContainer

Question

I'm struggling with mocking (using Mockito) the DefaultMessageListenerContainer (org.springframework.jms.listener.DefaultMessageListenerContainer). Here is my code:

@Mock
private DefaultMessageListenerContainer defaultMessageListenerContainer;

@Before
public void init() {

    MockitoAnnotations.initMocks( this );
    incomingFeedController = new IncomingFeedControllerImpl();

}

@Test 
public void testHandleConnectionState() { 
    List< DefaultMessageListenerContainer > listeners = 
        new ArrayList< DefaultMessageListenerContainer >(); 
    listeners.add( defaultMessageListenerContainer ); 
    incomingFeedController.setContainers( listeners ); 
    when( defaultMessageListenerContainer.isRunning() ).thenReturn( false );
}

Then I would like to do some proper tests like:

when( defaultMessageListenerContainer.isRunning() ).thenReturn( false );

But after junit run this line end up with:

java.lang.NullPointerException
    at org.springframework.jms.listener.AbstractJmsListeningContainer.isRunning(AbstractJmsListeningContainer.java:312)
    at com.source.etf.manager.integrationgateway.feedcontroller.IncomingFeedControllerTest.testHandleConnectionState(IncomingFeedControllerTest.java:37)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:59)
    at org.junit.internal.runners.MethodRoadie.runTestMethod(MethodRoadie.java:98)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:79)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:87)
    at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:77)
    at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:42)
    at org.junit.internal.runners.JUnit4ClassRunner.invokeTestMethod(JUnit4ClassRunner.java:88)
    at org.junit.internal.runners.JUnit4ClassRunner.runMethods(JUnit4ClassRunner.java:51)
    at org.junit.internal.runners.JUnit4ClassRunner$1.run(JUnit4ClassRunner.java:44)
    at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:27)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:37)
    at org.junit.internal.runners.JUnit4ClassRunner.run(JUnit4ClassRunner.java:42)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

I also checked the AbstractJmsListeningContainer and here is the code where NPE occures:

public final boolean isRunning() {
    synchronized (this.lifecycleMonitor) {
        return (this.running && runningAllowed());
    }
}

What I found is that the lifecycleMonitor object is not being instantiated. This object is declared in AbstractJmsListeningContainer just at the top:

protected final Object lifecycleMonitor = new Object();

Any idea how to properly mock DefaultMessageListenerContainer?

Answer 1

You still need to set the mock on the object you are initializing.

I see that you are testing IncomingFeedControllerImpl, and it is likely that your mocked object is a member of an instance of this class. Because you are not setting your mocked DefaultMessageListenerContainer on your IncomingFeedControllerImpl explicitly the AbstractJmsListeningContainer (which is probably @Autowired) is still hanging around and not being mocked.

You will need to either inject it by using a setter method or a constructor. (you can also @Autowired it)