Mocked method doesn't return expected result

Question

I want to mock method mockedMethod(Object object) that accept Object param. This object param is created from testedMethod dynamically. mockedMethod doesn't return expected result despite of that both objects have the same data, but only different hashCode.

Here is example

public void testedMethod() {
    Object object = initObject(); // this object is initialized dynamically
    Long result = mockedMethod(object);
    ...
}

@Test
public void test() {
    Object object = new Object();
    when(api.mockedMethod(object).thenReturn(3L);
    testedMethod();
}

Is there any way how to mock method, that it will be respond with expected result?

Do you actually care what the object that is passed as an argument is or can it be anything? — geoand, May 31 '14 at 21:23
Then you could try `when(api.mockedMethod(notNull()).thenReturn(3L)`. Let me know if that is what you actually wanted so I can add it as answer if so — geoand, May 31 '14 at 22:12

score 2 · Accepted Answer · edited May 23 '17 at 12:20

Seems like you have two options here:

Accept anything

You can use any() or notNull(), as geoand mentioned in the comments. These define behavior for any parameter (any) or any non-null parameter (notNull).

when(api.mockedMethod(Mockito.any()).thenReturn(3L);
// or
when(api.mockedMethod(Mockito.notNull()).thenReturn(3L);

These static methods return argument matchers, and can be found on the Mockito object inherited from the Matchers object (to keep the APIs a little bit separated).

Write your own custom matcher

If you need to check that the object matches some custom criteria, you could use a custom ArgumentMatcher object. These objects (otherwise known as Hamcrest matchers, as they come directly from the Hamcrest library) have exactly one boolean method, that returns true if the object matches the condition.

/** Returns true if the passed object has FooBar anywhere in its class name. */
class HasFooBarInClassName extends ArgumentMatcher<Object> {
  @Override public boolean matches(Object object) {
    return object.getClass().getName().contains("FooBar");
  }
}

when(api.mockedMethod(argThat(new HasFooBarInClassName())).thenReturn(3L);

Bonus: Capturing the Object

Sometimes your code will need to "capture" the object for additional verification or processing, in a way that Mockito can't do alone. You can use an ArgumentCaptor to help you out there:

ArgumentCaptor<Object> captor = ArgumentCaptor.for(Object.class);
when(api.mockedMethod(any()).thenReturn(3L);
testedMethod();
verify(api).mockedMethod(captor.capture());

// Now you can check the object, as needed, using your own methods.
checkObjectAsNeeded(captor.getValue());

score 1 · Answer 2 · answered May 31 '14 at 13:33

1

Of course it's not "expected"; you're passing a completely different object into the when clause, and the method's using its own from initObject(). You should either inject object into the class under test, or mockedMethod belongs on a service interface, and you should mock that.

answered May 31 '14 at 13:33

chrylis -cautiouslyoptimistic-

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Okay, I know your suggested solutions. But it is obliging me to change the API. I'm therefore looking for some other way how to solve it. – misco May 31 '14 at 14:32

Mocked method doesn't return expected result

2 Answers2

Accept anything

Write your own custom matcher

Bonus: Capturing the Object