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;
})

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;
})

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)。

在我简单地创建一个新的“Fake”类的实例来实现您试图Mock的任何接口之前，我在这里的许多建议中苦苦挣扎。然后，您可以简单地使用方法本身设置out参数的值。

对克雷格·塞莱斯特的答案进行了增强，任何人都可以使用它。out参数为IsAny:

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

[TestMethod]
public void Test()
{
    var service = GetService();
    string actualValue;
    service.Object.DoSomething(out actualValue);
    Assert.AreEqual(expectedValue, actualValue);
}

private IService GetService()
{
    var service = new Mock<IService>();
    var anyString = It.IsAny<string>();
    service.Setup(s => s.DoSomething(out anyString))
        .Callback((out string providedString) => 
        {
            providedString = "SomeValue";
        });
    return service.Object;
}

如果你的方法也需要返回一些东西，你也可以使用Returns而不是Callback。