这是一个解决方案。

[Test]
public void TestForOutParameterInMoq()
{
  //Arrange
  _mockParameterManager= new Mock<IParameterManager>();

  Mock<IParameter > mockParameter= new Mock<IParameter >();
  //Parameter affectation should be useless but is not. It's really used by Moq 
  IParameter parameter= mockParameter.Object;

  //Mock method used in UpperParameterManager
  _mockParameterManager.Setup(x => x.OutMethod(out parameter));

  //Act with the real instance
  _UpperParameterManager.UpperOutMethod(out parameter);

  //Assert that method used on the out parameter of inner out method are really called
  mockParameter.Verify(x => x.FunctionCalledInOutMethodAfterInnerOutMethod(),Times.Once());

}

在Billy Jakes awnser的基础上，我用一个out参数做了一个完全动态的模拟方法。我把这个贴在这里给那些觉得有用的人。

// Define a delegate with the params of the method that returns void.
delegate void methodDelegate(int x, out string output);

// Define a variable to store the return value.
bool returnValue;

// Mock the method: 
// Do all logic in .Callback and store the return value.
// Then return the return value in the .Returns
mockHighlighter.Setup(h => h.SomeMethod(It.IsAny<int>(), out It.Ref<int>.IsAny))
  .Callback(new methodDelegate((int x, out int output) =>
  {
    // do some logic to set the output and return value.
    output = ...
    returnValue = ...
  }))
  .Returns(() => returnValue);

对于“out”，下面的方法似乎对我有用。

public interface IService
{
    void DoSomething(out string a);
}

[TestMethod]
public void Test()
{
    var service = new Mock<IService>();
    var expectedValue = "value";
    service.Setup(s => s.DoSomething(out expectedValue));

    string actualValue;
    service.Object.DoSomething(out actualValue);
    Assert.AreEqual(expectedValue, actualValue);
}

我猜当你调用Setup并记住它时，Moq会查看“expectedValue”的值。

作为裁判，我也在寻找答案。

我发现下面的快速入门指南很有用: https://github.com/Moq/moq4/wiki/Quickstart

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;
         }));
    }

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。

就像这样:

被嘲笑的方法是

public bool GenerateClient(out Client client);

那么模拟部分将是:

Client client = new Client();
clintMockBll
.Setup(x => x.GenerateClient(out client))
.Returns((Client client1) =>
{
   client = new Client(){Name="Something"};
   return true;
});