Moq版本4.8(或更高版本)对by-ref参数的支持有了很大的改进:

public interface IGobbler
{
    bool Gobble(ref int amount);
}

delegate void GobbleCallback(ref int amount);     // needed for Callback
delegate bool GobbleReturns(ref int amount);      // needed for Returns

var mock = new Mock<IGobbler>();
mock.Setup(m => m.Gobble(ref It.Ref<int>.IsAny))  // match any value passed by-ref
    .Callback(new GobbleCallback((ref int amount) =>
     {
         if (amount > 0)
         {
             Console.WriteLine("Gobbling...");
             amount -= 1;
         }
     }))
    .Returns(new GobbleReturns((ref int amount) => amount > 0));

int a = 5;
bool gobbleSomeMore = true;
while (gobbleSomeMore)
{
    gobbleSomeMore = mock.Object.Gobble(ref a);
}

同样的模式也适用于参数。

It.Ref < T >。IsAny也适用于c# 7的参数(因为它们也是by-ref)。

下面是一个正在工作的例子。

[Fact]
public void DeclineLowIncomeApplicationsOutDemo()
{
    var mockValidator = new Mock<IFrequentFlyerNumberValidator>();

    var isValid = true; // Whatever we set here, thats what we will get.

    mockValidator.Setup(x => x.IsValid(It.IsAny<string>(), out isValid));

    var sut = new CreditCardApplicationEvaluator(mockValidator.Object);

    var application = new CreditCardApplication
    {
        GrossAnnualIncome = 19_999,
        Age = 42
    };

    var decision = sut.EvaluateUsingOut(application);

    Assert.Equal(CreditCardApplicationDecision.AutoDeclined, decision);
}

public interface IFrequentFlyerNumberValidator
{
    bool IsValid(string frequentFlyerNumber);
    void IsValid(string frequentFlyerNumber, out bool isValid);
}

注意，在设置中没有return，因为没有return。

这是来自Moq网站的文档:

// out arguments
var outString = "ack";
// TryParse will return true, and the out argument will return "ack", lazy evaluated
mock.Setup(foo => foo.TryParse("ping", out outString)).Returns(true);


// ref arguments
var instance = new Bar();
// Only matches if the ref argument to the invocation is the same instance
mock.Setup(foo => foo.Submit(ref instance)).Returns(true);

为了返回一个值和设置ref参数，这里有一段代码:

public static class MoqExtensions
{
    public static IReturnsResult<TMock> DelegateReturns<TMock, TReturn, T>(this IReturnsThrows<TMock, TReturn> mock, T func) where T : class
        where TMock : class
    {
        mock.GetType().Assembly.GetType("Moq.MethodCallReturn`2").MakeGenericType(typeof(TMock), typeof(TReturn))
            .InvokeMember("SetReturnDelegate", BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance, null, mock,
                new[] { func });
        return (IReturnsResult<TMock>)mock;
    }
}

然后声明自己的与要模拟方法的签名匹配的委托，并提供自己的方法实现。

public delegate int MyMethodDelegate(int x, ref int y);

    [TestMethod]
    public void TestSomething()
    {
        //Arrange
        var mock = new Mock<ISomeInterface>();
        var y = 0;
        mock.Setup(m => m.MyMethod(It.IsAny<int>(), ref y))
        .DelegateReturns((MyMethodDelegate)((int x, ref int y)=>
         {
            y = 1;
            return 2;
         }));
    }

在VS2022中，你可以简单地做:

foo.Setup(e => e.TryGetValue(out It.Ref<ExampleType>.IsAny))
.Returns((ref ExampleType exampleType) => {
exampleType = new ExampleType();
return true;
})

似乎不可能开箱即用。看来有人想要解决问题

请看这个论坛帖子 http://code.google.com/p/moq/issues/detail?id=176

这个问题 用最小订货量验证参考参数的值