@Test
public void execute() {

    RegistryContext registryContext = new ContextImpl();
    GetDMNMessagesCommand getDMNMessagesCommand = new GetDMNMessagesCommand();
    assertThatThrownBy(() -> getDMNMessagesCommand.execute(registryContext))
            .isInstanceOf(IllegalStateException.class)
            .hasMessage("There is no DMNResult available");
    DMNResultImpl dmnResult = new DMNResultImpl(null);
    dmnResult.setContext(new DMNContextImpl());
    registryContext.register(DMNResult.class, dmnResult);
    List<DMNMessage> result = getDMNMessagesCommand.execute(registryContext);
    assertEquals(0, result.size());
}