mockito与第三方课程

Question

I need to use a third party class in Mockito.when as parameter. The class does not have equals implementation and hence Mockito.when always returns null except the case where any() is used.

The below always returns null:

when(obj.process(new ThirdParytClass())).thenReturn(someObj);

however, this works

when(obj.process(any(ThirdParytClass.class))).thenReturn(someObj);

But, the problem is the process() method is called twice in the actual code and the use of any() is ambiguous and does not help in covering the multiple scenarios to test.

Extending the class does not help and also leads to other complications.

Is there a way to address the issue.

Answer 1

If a class doesn't implement a (sensible) equals(Object) , you can always match instances yourself by implementing your own ArgumentMatcher . Java 8's functional interfaces make this pretty easy to write (not that it was such a big hardship in earlier versions, but still):

when(obj.process(argThat(tpc -> someLogic()))).thenReturn(someObj);

More often than not, however, if you just want to compare the class' data members, the built-in refEq matcher would do the trick:

ThirdParytClass expected = new ThirdParytClass();
// set the expected properties of expected

when(obj.process(refEq(expected))).thenReturn(someObj);

Answer 2

Mockito provides the captor feature that may help you to bypass limitations of equals() method because overriding equals() to make a test pass may be desirable but it is not always the case.
And besides, sometimes, equals() may not be overridable. It is your use case.

Here is a example code with an ArgumentCaptor :

@Mock
MyMockedClass myMock;

@Captor
ArgumentCaptor argCaptor;

@Test
public void yourTest() {
    ThirdPartyClass myArgToPass = new ThirdPartyClass();
    // call the object under test
     ...
    //
    Mockito.verify(myMock).process(argCaptor.capture());
    // assert the value of the captor argument is the expected onoe
    assertEquals(myArgToPass , argCaptor.getValue());
}