Moq SetupSequence 不起作用

Question

我尝试使用Moq 4.5框架的SetupSequence方法

Class 应该被嘲笑的：

public class OutputManager {
    public virtual string WriteMessage(string message) {
    // write a message
    }
}

模拟：

var outputManagerMock = new Mock<OutputManager>();
var writeMessageCalls = 0;
var currentMessage = String.Empty;

outputManagerMock.Setup(o => o.WriteMessage(It.IsAny<string>())).Callback((string m) => {
    writeMessageCalls++;
    message = m;
});

这段代码工作正常。但是我想对 WriteMessage 方法的每次调用进行不同的设置。好吧，我使用 SetupSequence 而不是 Setup:

var outputManagerMock = new Mock<OutputManager>();
var writeMessageCalls = 0;
var firstMessage = String.Empty;
var secondMessage = String.Empty;

outputManagerMock.SetupSequence(o => o.WriteMessage(It.IsAny<string>()))
.Callback((string m) => {
    writeMessageCalls++;
    firstMessage = m;
}).Callback((string m) => {
    writeMessageCalls++;
    secondMessage = m;
});

然后我得到了错误：

Error CS0411 The type arguments for method
'SequenceExtensions.SetupSequence<TMock, TResult>(Mock<TMock>, Expression<Func<TMock, TResult>>)' cannot be inferred from the usage.
Try specifying the type arguments explicitly.

我在这里找到了可能的解决方案 - SetupSequence in Moq。但它看起来像是一种解决方法。

Answer 1

SetupSequence 用于根据尝试使用正在设置的方法的次数设置 returns 的序列。基于您的代码的示例演示了我在说什么：

outputManagerMock.SetupSequence(o => o.WriteMessage(It.IsAny<string>()))
.Returns("Hello for the first attempt!")
.Returns("This is the second attempt to access me!")
.Throws(new Exception());

Answer 2

如果 OutputManager 是其他 classes 的依赖项，那么您应该考虑抽象化 class 以便更容易模拟您的测试。

public interface IOutputManager {
    string WriteMessage(string message);
}

那就意味着这个接口的实现看起来就像你最初添加接口的样子。

public class OutputManager : IOutputManager {
    public string WriteMessage(string message) {
        // write a message
    }
}

鉴于您最初尝试模拟 OutputManager 那么这里的假设是它不是被测系统，因为您通常不模拟测试目标而是模拟其依赖项。

所以让我们假设一个受抚养人 class 看起来像这样。

public class DependentOnIOutputManager {
    private IOutputManager outputManager;

    public DependentOnIOutputManager(IOutputManager outputManager) {
        this.outputManager = outputManager;
    }

    public string SomeMethod(string message) {        
        // write a message
        var output = outputManager.WriteMessage(message);
        //...other code
        return output;
    }
}

然后示例测试可能如下所示。

[TestMethod]
public void Moq_SetupSequence_Example() {
    //Arrange
    var mock = new Mock<IOutputManager>();

    mock.SetupSequence(x => x.WriteMessage(It.IsAny<string>()))
        .Returns("first")
        .Returns("second")
        .Throws<InvalidOperationException>();

    var outputManager = mock.Object;

    var sut = new DependentOnIOutputManager(outputManager);

    //Act
    var first = sut.SomeMethod("1st");

    var second = sut.SomeMethod("2nd");

    Exception e = null;
    try {
        sut.SomeMethod("3rd");
    } catch (InvalidOperationException ex) {
        e = ex;
    }

    //Assert
    Assert.IsNotNull(first);
    Assert.IsNotNull(second);
    Assert.IsNotNull(e);
}

Moq SetupSequence 不起作用

Moq SetupSequence doesn't work

c#

asp.net

unit-testing

moq