[英]Moq mocked call returns null if using setup
我正在使用Moq为C#应用程序编写测试。 我的测试初始化程序具有以下代码:
UnityContainer unityContainer = new UnityContainer();
_serviceMock = new Mock<IService>();
_serviceMock.Setup(mock => mock.GetSearchInfoAsync(It.IsAny<CancellationToken>(), It.IsAny<IEnumerable<string>>(), It.IsAny<identifierType>(), It.IsAny<bool>())).Callback(() => _count++);
unityContainer.RegisterInstance(typeof(IService), _serviceMock.Object, new ContainerControlledLifetimeManager());
我想测试一次呼叫只进行一次。 我这样想:
int _count = 0;
[TestMethod]
public void Properties_Test()
{
_serviceMock.Verify(mock => mock.GetSearchInfoAsync(It.IsAny<CancellationToken>(), It.IsAny<IEnumerable<string>>(), It.IsAny<identifierType>(), It.IsAny<bool>()), Times.Exactly(1), "Invocation was performed " + _count + " times but was expected only once!");
}
这是实际调用它的方法:
private void Search(string queryValue, identifierType identifierType)
{
CancellationToken cancellationToken;
lock (_syncLock)
{
_cancellationTokenSource.Cancel();
_cancellationTokenSource = new CancellationTokenSource();
cancellationToken = _cancellationTokenSource.Token;
}
IService Service = ServiceLocator.Current.GetInstance<IService>();
Service.GetSearchInfoAsync(cancellationToken, new[] {queryValue}, identifierType)
.ContinueWith(
task =>
{
// Do stuff
}, CancellationToken.None, TaskContinuationOptions.None, TaskScheduler.Default);
}
问题是,如果我如上所述使用此行,
_serviceMock.Setup(mock => mock.GetSearchInfoAsync(It.IsAny<CancellationToken>(), It.IsAny<IEnumerable<string>>(), It.IsAny<identifierType>(), It.IsAny<bool>())).Callback(() => _count++);
这将返回null并生成NullPointerException:
Service.GetSearchInfoAsync(cancellationToken, new[] {queryValue}, identifierType)
但是,如果我注释掉该行,则测试运行正常(尽管不计算调用次数)。
我究竟做错了什么? 这是我第一次使用Moq,据我所知,我已正确实现了计数功能。
编辑:按照Chris Sinclair的建议,我已将初始化更改为此,这解决了问题:
UnityContainer unityContainer = new UnityContainer();
_serviceMock = new Mock<IService>();
Task<IEnumerable<ISearchResult>> task = new Task<IEnumerable<ISearchResult>>(Enumerable.Empty<ISearchResult>);
_serviceMock.Setup(mock => mock.GetSearchInfoAsync(It.IsAny<CancellationToken>(), It.IsAny<IEnumerable<string>>(), It.IsAny<identifierType>(), It.IsAny<bool>())).Returns(task).Callback(() => _count++);
unityContainer.RegisterInstance(typeof(IService), _serviceMock.Object, new ContainerControlledLifetimeManager());
当您“设置”该方法时,您设置回调但不提供返回值。 因此,当调用mocked方法时,它将返回返回类型的默认值(在这种情况下, Task<>
类型将返回null
返回值)。 因此,当你的Search
方法调用你的嘲笑GetSearchInfoAsync
方法,它收到一个null
引用时,它后来试图调用这自然无法.ContinueWith
就可以了。
尝试添加.Returns()
,它将伪Task<>
给您的模拟方法:
_serviceMock.Setup(mock => mock.GetSearchInfoAsync(It.IsAny<CancellationToken>(), It.IsAny<IEnumerable<string>>(), It.IsAny<identifierType>(), It.IsAny<bool>()))
.Returns(new Task<IEnumerable<ISearchResult>>(Enumerable.Empty<ISearchResult>))
.Callback(() => _count++);
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