Mockito verify on Class object NotAMockException

Question

i'm trying to write a test for the following static method:

public static Field getField (Class<?> type, String fieldName) {
    for (Field field : type.getDeclaredFields()) {
        if (field.getName().equals(fieldName)) {
            return field;
        }
    }

    if (type.getSuperclass() != null) {
        return getField(type.getSuperclass(), fieldName);
    }

    return null;
}

This is my test code:

@Test
public void getFieldTest () {
    class StupidObject { Object stupidField; }
    class ReallyStupidObject extends StupidObject { Object reallyStupidField; }
    ReallyStupidObject reallyStupidObject = mock(ReallyStupidObject.class);
    // --------------------------------------------------
    Field field = FSUtils.getField(reallyStupidObject.getClass(), "stupidField");
    // --------------------------------------------------
    verify(reallyStupidObject.getClass()).getDeclaredFields();
    verify(reallyStupidObject.getClass()).getSuperclass();
    verify(reallyStupidObject.getClass().getSuperclass()).getDeclaredFields();
    verify(reallyStupidObject.getClass().getSuperclass(), never()).getSuperclass();
    assertEquals(field.getName(), "stupidField");
}

Which results in this error:

org.mockito.exceptions.misusing.NotAMockException: Argument passed to verify() is of type Class and is not a mock!

Can anyone shed some light on how i can verify methods are called on Class objects?

Many thanks!

Ben.

Answer 1

This doesn't seem like a problem that should be solved with mocking. I would opt for a concrete test like this:

@Test
public void getFieldTest() {
    class StupidObject { Object stupidField; }
    class ReallyStupidObject extends StupidObject { Object reallyStupidField; }

    // test the right field is found in the right class
    testFieldFind("stupidField", ReallyStupidObject.class,
            StupidObject.class);
    testFieldFind("reallyStupidField", ReallyStupidObject.class,
            ReallyStupidObject.class);

    // check that non-existent fields return null
    assertNull(FSUtils.getField(ReallyStupidObject.class, "fooballs"));
}

private static void testFieldFind(String fieldName, Class<?> classToSearch,
        Class<?> expectedDeclaringClass) {
    Field field = FSUtils.getField(classToSearch, fieldName);
    assertEquals(fieldName, field.getName());
    assertEquals(expectedDeclaringClass, field.getDeclaringClass());
}

As to why your original code failed - you have to call verify on your mocked object, i.e. verify(reallyStupidObject).doSomething().

Answer 2

The reallyStupidObject.getClass() - returns a class not a mock object.

Your mock is the reallyStupidObject.