How do I mock Spring ApplicationContext's getBean method using Mockito for writing unit tests with TestNG?

Question

I am writing unit tests for the following class

Class to Be Tested:

public class RandomManager {
        @Autowired
        private ApplicationContext context;

        @Autowired
        private ClassA objectA;

        public void methodToBeTested() {
            objectA.methodToBeVerified(context.getBean(Random.class,"Yaswanth","Yaswanth"));
        }
    }

Below is the test class:

public class RandomManagerTest {

    @Mock
    private ClassA objectA;

    @Mock
    private ApplicationContext context;

    @InjectMocks
    private RandomManager randomManager;

    @BeforeTest
    public void before() {
        MockitoAnnotations.initMocks(this);
        doReturn(any(Random.class)).when(context)
            .getBean(any(Class.class), any(), any());
    }

    @Test
    public void methodToBeTestedTest() {
        Random randomObject = new RandomObject("Yaswanth", "Yaswanth");
        randomManager.methodToBeTested();
        verify(objectA).methodToBeVerified(randomObject);
    }
}

The above code fails in the before method when I am trying to stub the applicationContext mock. I get the following error.

You cannot use argument matchers outside of verification or stubbing. Examples of correct usage of argument matchers: when(mock.get(anyInt())).thenReturn(null); doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject()); verify(mock).someMethod(contains("foo"))

This message may appear after an NullPointerException if the last matcher is returning an object like any() but the stubbed method signature expect a primitive argument, in this case, use primitive alternatives. when(mock.get(any())); // bad use, will raise NPE when(mock.get(anyInt())); // correct usage use

Also, this error might show up because you use argument matchers with methods that cannot be mocked. Following methods cannot be stubbed/verified: final/private/equals()/hashCode(). Mocking methods declared on non-public parent classes is not supported.

Can anyone please help me understand what am I doing wrong in the above code?

Note: I am using TestNG and Mockito. I can extend AbstractTestNGSpringContextTests and use a spring-test.xml, declare my beans and autowire applicationContext. I feel that is an overkill for my use case. I need to just mock applicationContext's getBean method.

Solution

The issue comes from doReturn(any(Random.class)) where you are not allowed to use any(). Just replace it by a real instance.