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);

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;
});

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());

}

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。

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);