@Test
public void scanHandledMessageTypes_sagaWithHandler_returnsHandler() throws ExecutionException {

    // given
    mockSaga(String.class);
    // when
    Map<Class<? extends Saga>, SagaHandlersMap> classSagaHandlersMapMap = sut.scanHandledMessageTypes();
    // then
    assertThat("Expected saga type to be present.", classSagaHandlersMapMap.containsKey(TestSaga.class), is(true));
    Collection<MessageHandler> handlers = classSagaHandlersMapMap.get(TestSaga.class).messageHandlers();
    assertThat("Expected handlers map to contain handler type.", handlers.iterator().next().getMessageType(), equalTo(String.class));
    assertThat("Expected handlers map to to be starting type.", handlers.iterator().next().getStartsSaga(), is(true));
}