带约束的 Moq 表达式 ... It.Is<Expression<Func<T, bool>>>

Question

好的，我很难弄清楚如何为采用表达式的方法设置最小起订量。有很多关于如何 It.IsAny<>... 的示例，这不是我想要的。我在做约束之后，所以 It.Is<>。我已经设置了它，但它从未 return 达到我要求它 return 的值。

// Expression being setup
Expression<Func<UserBinding, bool>> testExpression = binding =>
binding.User.Username == "Testing Framework";


// Setup of what expression to look for. 
 this.bindingManager.Setup(
            c => c.GetUserBinding(It.Is<Expression<Func<UserBinding, bool>>>
(criteria => criteria == testExpression)))
            .Returns(new List<UserBinding>() { testBinding }.AsQueryable());

// Line of code call from within the class being tested. So this is being mocked and should return the defined object when the same lambda is passed in.
 this.bindingManager.GetUserBinding(b => b.User.Username == username)
                .SingleOrDefault();

// class under test. So for the test this is being called. 
// so this is the method being called and inside this method is where the binding manager is being mocked and called. 
var response = this.controller.SendMessage(message, true).Result;

        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);

 // inside the controller.SendMessage method this method is called with the lambda expression. I have verified the usernames match but when the setup is It.Is this returns null instead of the object setup in the "setup" call. 
this.bindingManager.GetUserBinding(b => b.User.Username == username)
                .SingleOrDefault();

如果我将设置更改为 It.IsAny... 它会起作用并且 return 是 "returns" 方法中的预期对象设置。

我在网上找到了几个如何执行此操作的示例，一个是这样做的，另一个是使用编译，但我也无法使其工作。您如何使它适用于特定表达式？

根据答案更新工作解决方案

@carlos-alejo 让我朝着正确的方向前进，或者至少让我回到了编译操作。我想错了。我现在有基于使用编译的解决方案。关于 compile 要理解的关键是你给它一个对象，通过它 evaluate/generate 表达式。

所以在我的情况下，如果有人给我这样的表达：

binding => binding.User.Username == "Testing Framework";

我需要这样的 UserBinding：

var testBinding = new UserBinding { Binding = new Binding { Name = "Default binding" }, Domain = "test.com", User = new User() { Username = "Testing Framework" } };

然后我可以像这样创建我的 "setup" 调用：

this.bindingManager.Setup(c => c.GetUserBinding(It.Is<Expression<Func<UserBinding, bool>>>(y => y.Compile()(testBinding))))
        .Returns(new List<UserBinding>() { testBinding }.AsQueryable());

这有效，在我的情况下，return让我返回测试绑定对象，因为我已设置。如果将 testBinding 更改为 （注意我更改了用户名）:

    var testBinding = new UserBinding { Binding = new Binding { Name = "Default binding" }, Domain = "test.com", User = new User() { Username = "Testing Framework2" } };

它不会工作，因为我的被测系统中的代码会生成一个表达式来寻找 "Test Framework"

也许只是我没有把这些点联系起来，但希望它能帮助其他人。

Answer 1

这里真正的问题似乎是如何比较两个 lambda 表达式，正如您在 It.Is<Expression<Func<UserBinding, bool>>> (criteria => criteria == testExpression) 子句中尝试做的那样。使用@neleus 的 answer to this question，我可以想出这个实际通过的测试：

readonly Mock<IBindingManager> bindingManager = new Mock<IBindingManager>();
    
[Test]
public void TestMethod()
{
    Expression<Func<string, bool>> testExpression = binding => (binding == "Testing Framework");
        
    bindingManager.Setup(c => c.GetUserBinding(It.Is<Expression<Func<string, bool>>>(
        criteria => LambdaCompare.Eq(criteria, testExpression)))).Returns(new List<string>());
        
    var oc = new OtherClass(bindingManager.Object);
        
    var actual = oc.Test(b => b == "Testing Framework");
        
    Assert.That(actual, Is.Not.Null);
    bindingManager.Verify(c => c.GetUserBinding(It.Is<Expression<Func<string, bool>>>(
        criteria => LambdaCompare.Eq(criteria, testExpression))), Times.Once());
}

请注意使用LambdaCompare.Eq静态方法来比较表达式是否相同。如果我将表达式与 == 甚至 Equals 进行比较，则测试失败。

Answer 2

当我在寻找模拟 Where() 和过滤一些数据的方法时，在被测代码中看起来像：

Repository<Customer>().Where(x=>x.IsActive).ToList()

我可以根据其他人的回答设计这样的例子：

 var inputTestDataAsNonFilteredCustomers = new List<Customer> {cust1, cust2};
 var customersRepoMock = new Mock<IBaseRepository<Customer>>();

                IQueryable<Customer> filteredResult = null;
                customersRepoMock.Setup(x => x.Where(It.IsAny<Expression<Func<Customer, bool>>>()))
                    .Callback((Expression<Func<Customer, bool>>[] expressions) =>
                    {
                        if (expressions == null || expressions.Any() == false)
                        {
                            return;
                        }
                        Func<Customer, bool> wereLambdaExpression = expressions.First().Compile();  //  x=>x.isActive is here
                        filteredResult = inputTestDataAsNonFilteredCustomers.Where(wereLambdaExpression).ToList().AsQueryable();// x=>x.isActive was applied
                    })
                   .Returns(() => filteredResult.AsQueryable());

也许对羽毛开发者有帮助。

带约束的 Moq 表达式 ... It.Is<Expression<Func<T, bool>>>

Moq Expression with Constraint ... It.Is<Expression<Func<T, bool>>>

c#

moq

根据答案更新工作解决方案