[英]Moq mocked call returns null if using setup
I am writing tests for a C# application, using Moq. 我正在使用Moq为C#应用程序编写测试。 My test initialiser has the following code:
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());
I want to test that a call is made only once. 我想测试一次呼叫只进行一次。 I am trying it like this:
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!");
}
This is the method where it actually gets called: 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);
}
The problem is that if I use this line as detailed above, 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++);
this returns null and generates a NullPointerException: 这将返回null并生成NullPointerException:
Service.GetSearchInfoAsync(cancellationToken, new[] {queryValue}, identifierType)
However, if I comment out that line, the tests run fine (albeit not counting the number of calls). 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)。
What am I doing wrong? 我究竟做错了什么? This is my first time using Moq for this and as far as I can tell I've implemented the count functionality correctly.
这是我第一次使用Moq,据我所知,我已正确实现了计数功能。
EDIT: Following Chris Sinclair's suggestion, I've changed the initialiser to this, which fixed the issue: 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());
When you "Setup" the method, you set a callback but you don't provide a return value. 当您“设置”该方法时,您设置回调但不提供返回值。 As such, when the mocked method is called, it will return the default value for the return type (in this case, a
Task<>
type will result in a null
return value). 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)。 As such, when your Search
method calls your mocked GetSearchInfoAsync
method, it receives a null
reference which naturally fails when it later attempts to invoke .ContinueWith
on it. 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。
Try adding a .Returns()
which feeds a dummy Task<>
to your mocked method: 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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