@Test
public void superClasses_ConcreteMessage_returnsSuperClassTypes() {

    // given
    ClassTypeExtractor sut = new ClassTypeExtractor(ConcreteMessage.class);
    // when
    Iterable<Class<?>> classes = sut.allClasses();
    // then
    assertThat("Expected list of super classes.", classes, hasItems(ConcreteMessage.class, BaseMessage.class, Object.class));
}