如何使用mock为不同的参数设置两次方法

Question

我想用Moq设置一个方法两次,但似乎最后一个覆盖了之前的方法.这是我的初始设置:

string username = "foo";
string password = "bar";

var principal = new GenericPrincipal(
    new GenericIdentity(username),
    new[] { "Admin" });

var membershipServiceMock = new Mock<IMembershipService>();
membershipServiceMock.Setup(ms =>
    ms.ValidateUser(username, password)
).Returns(new ValidUserContext { 
    Principal = principal
});

这很好但我希望这返回new ValidUserContext()如果用户名或密码而不是上面的username和password变量.为此,我添加了另一个设置,但这次它会覆盖上面的设置并始终应用它:

membershipServiceMock.Setup(ms =>
    ms.ValidateUser(It.IsAny<string>(), It.IsAny<string>())
).Returns(
    new ValidUserContext()
);

使用Moq处理此类情况的最优雅方式是什么？

编辑

我通过以下方法解决了问题,但我想有更好的方法来处理这个问题:

var membershipServiceMock = new Mock<IMembershipService>();
membershipServiceMock.Setup(ms =>
    ms.ValidateUser(It.IsAny<string>(), It.IsAny<string>())
).Returns<string, string>((u, p) => 
    (u == username && p == password) ?
    new ValidUserContext { 
        Principal = principal
    }
    : new ValidUserContext()
);

Answer 1

Moq通过参数约束支持这个开箱即用:

mock.Setup(ms => ms.ValidateUser(
        It.Is<string>(u => u == username), It.Is<string>(p => p == password))
    .Returns(new ValidUserContext { Principal = principal });
mock.Setup(ms => ms.ValidateUser(
        It.Is<string>(u => u != username), It.Is<string>(p => p != password))
    .Returns(new ValidUserContext());

Catch-all It.IsAny也有效,但订单很重要:

// general constraint first so that it doesn't overwrite more specific ones
mock.Setup(ms => ms.ValidateUser(
        It.IsAny<string>(), It.IsAny<string>())
    .Returns(new ValidUserContext());
mock.Setup(ms => ms.ValidateUser(
        It.Is<string>(u => u == username), It.Is<string>(p => p == password))
    .Returns(new ValidUserContext { Principal = principal });

Answer 2

如果您查看 的函数定义Setup()：

// Remarks:
//     If more than one setup is specified for the same method or property, the latest
//     one wins and is the one that will be executed.
public ISetup<T, TResult> Setup<TResult>(Expression<Func<T, TResult>> expression);

您需要做的就是切换两个调用的顺序Setup()：

membershipServiceMock.Setup(ms =>
    ms.ValidateUser(It.IsAny<string>(), It.IsAny<string>())
).Returns(
    new ValidUserContext()
);
membershipServiceMock.Setup(ms =>
    ms.ValidateUser(username, password)
).Returns(new ValidUserContext { 
    Principal = principal
});

因此，如果输入确实是usernameand password，则两个Setup()调用都符合条件，但由于规则而后一个调用获胜，并且当您有任何其他输入时，仅匹配并应用第一个调用。

Answer 3

另一个开箱即用的选项是使用 Return<> 版本根据参数返回不同的 ValidUserContext。它并不比上面的答案更好，只是另一种选择。

我们设置 ValidateUser() 返回函数 GetUserContext(string, string) 的结果，传入调用 ValidateUser() 时使用的用户名和密码。

[TestClass]
public class MultipleReturnValues {

    public class ValidUserContext {
        public string Principal { get; set; }
    }

    public interface IMembershipService {
        ValidUserContext ValidateUser(string name, string password);
    }

    [TestMethod]
    public void DifferentPricipals() {

        var mock = new Mock<IMembershipService>();
        mock.Setup(mk => mk.ValidateUser(It.IsAny<string>(), It.IsAny<string>())).Returns<string, string>(GetUserContext);

        var validUserContext = mock.Object.ValidateUser("abc", "cde");

        Assert.IsNull(validUserContext.Principal);


        validUserContext = mock.Object.ValidateUser("foo", "bar");

        Assert.AreEqual(sPrincipal, validUserContext.Principal);


    }

    private static string sPrincipal = "A Principal";
    private static ValidUserContext GetUserContext(string name, string password) {

        var ret = new ValidUserContext();

        if (name == "foo" && password == "bar") {
            ret = new ValidUserContext { Principal = sPrincipal };
        }
        return ret;

    }
}