CODEWITHSUNDEEP
unit-testingmockito
Akhil Sharma
Akhil Sharma

Reputation: 151

Advantages of InjectMocks for ClassUnderTest

I am writing unit test for my service (ClassUnderTest) class. I am using @Mock for all the data members.

Now, to test the ClassUnderTest, I need to create an object for the ClassUnderTest.

I have two options, Create a new object for ClassUnderTest and send the mocks in the constructor.

Or use the @InjectMocks annotation for the ClassUnderTest.

I was wondering, are the two approaches same or are their some attentional benefits of using @InjectMocks?

@Mock
private NodeLaunchWorkflowService nodeLaunchWorkflowService;

@InjectMocks
private NodeLaunchWorkflowController nodeLaunchWorkflowController;

or

@Mock
private NodeLaunchWorkflowService nodeLaunchWorkflowService;

private NodeLaunchWorkflowController nodeLaunchWorkflowController; 
@Before
public void setUp() throws JSONException {
    MockitoAnnotations.initMocks(this);
    nodeLaunchWorkflowController = new NodeLaunchWorkflowController(nodeLaunchWorkflowService)
}

Upvotes: 0

Views: 235

Answers (1)

Jeff Bowman
Jeff Bowman

Reputation: 95704

It's quite the opposite: There is some clear advantage to using the constructor pattern rather than @InjectMocks. In particular, as the @InjectMocks documentation and other articles, there are a wide variety of reasons that Mockito will silently fail to inject mocks. This means that innocent-looking class changes may cause obscure failures in your test, as opposed to the clear compilation failures that a constructor call would cause.

With certain automated refactoring tools, you may even be able to change your class in ways that your test will change correctly and automatically as well; it won't with @InjectMocks, which makes the constructor call reflectively deep within Mockito.

@InjectMocks may be useful for very quick unit test coverage in legacy code, but in new development it's usually much better to structure your components to be easily-testable (with exposed constructor calls, for instance) and then to test them with clear calls.

Upvotes: 1

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