Mockito Allow different argument types to mock overloaded method

Question

For JUnit testing I want to mock an overloaded method. There is no need to implement several methods in the mockbuilder though. I want to do something like this:

Mockito.when(mock.getSomeInfo(Mockito.any(ArgumentType1.class) OR Mockito.any(ArgumentType2.class), Mockito.any(ArgumentType3.class))).then(new Answer<AnswerType>() {..}

I know it doesn't work with the OR statement, but is there another way to do this in Mockito?

Answer 1

As mentioned on the mockito github:

It looks like this has to do with calling when the second time. I couldn't find what was going on, but the second when doesn't attempt to add the mock logic, it just calls the method. Replacing with doReturn().when() works.

    doReturn(expected1).when(overloadedMethods).getString(any());
    doReturn(expected2).when(overloadedMethods).getString(any(), any());

https://github.com/mockito/mockito/issues/1496#issuecomment-423310950 DavidTanner

Answer 2

You can do this with a custom matcher.

Warning: Be reasonable with using complicated argument matching, especially custom argument matchers, as it can make the test less readable. Sometimes it's better to implement equals() for arguments that are passed to mocks (Mockito naturally uses equals() for argument matching). This can make the test cleaner.

---

public class TypeOrMatcher extends ArgumentMatcher<Object> {

  private final List<Class<?>> clazzes;

  public TypeOrMatcher(Class<?>...clazzes) {
    this.clazzes = new ArrayList<Class<?>>(clazzes);
  }

  public boolean matches(Object actual) {
    if (actual == null) {
      return false;
    }
    Class<?> actualClass = actual.getClass();
    for (Class<?> clazz : clazzes) {
      if (clazz.isAssignableFrom(actualClass) {
        return true;
      }
    }
    return false;
  }
}

TypeOrMatcher isTypeOneOrTwo = new TypeOrMatcher(
    ArgumentType1.class, ArgumentType2.class); 

Some mockObj = mock(Some.class);
when(mockObj.someMethod(argThat(isTypeOneOrTwo), any(ArgumentType3.class))
    .thenReturn(true);