Question

我是模拟的新手，我试图做这个模拟示例：

Repository.cs

public class Repository : IRepository
{
    public List<Person> GetForExpression(Expression<Func<Person,bool>> expression  )
    {
        ... //get person from orm using expression
    }
}

PersonService.cs

public class PersonService
{
    private IRepository _repository;
    public PersonService(IRepository repository)
    {
        _repository = repository;
    }

    public List<Person> GetAllPersonsWith18More()
    {            
        var result = _repository.GetForExpression(x => x.Age > 18);

        return result;

    }
}

测试：

[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestMethod1()
    {
        var moqRepository = new Mock<IRepository>();
        var service = new PersonService(moqRepository.Object);
        Expression<Func<Person, bool>> criteria = y => y.Age  18;
        moqRepository.Setup(x => x.GetForExpression(It.Is<Expression<Func<Person, bool>>>(y => y == criteria))).Returns(new List<Person>());
        service.GetAllPersonsWith18More();
        moqRepository.VerifyAll();
    }
}

如果我使用此设置工作： moqRepository.Setup（x =＆gt; x.GetForExpression（It.IsAny＆gt;＆gt;（）））。返回（new List（））;

但我想使用更具体的标准，这只是我展示我需要的一个例子。

这个例子不匹配，任何人都可以帮助理解为什么并解决这个问题吗？

Answer 1

表达式不具有可比性，因此即使表达式树完全匹配，==也将返回false：

int criteria = 5;
Expression<Func<int, bool>> criteria1 = y => y == criteria;
Expression<Func<int, bool>> criteria2 = y => y == criteria;
System.Diagnostics.Debug.WriteLine(criteria1 == criteria2); // false

作为解决方法，您可以调用expression.ToString（）并比较字符串表示：Comparing Simple Lambda Expressions With Moq。

Answer 2

无法像那样比较表达式。如果要在这么详细的情况下匹配表达式，则需要将传递给mock的表达式解析并解析它的树（如this answer中所述）。结果看起来像这样（在上一个答案中可以找到FuncTest.FuncEqual）：

moqRepository
    .Setup(x => x.GetForExpression(ExpressionMatches(criteria))
    .Returns(new List<Person>());

// ...

public static Expression<Func<TSource, TValue>> ExpressionMatches(Expression<Func<TSource, TValue>> expr)
{
    return Match.Create<Expression<Func<TSource, TValue>>(actualExpr => FuncTest.FuncEqual(expr, actualExpr));
}

Answer 3

如果需要测试代理，我通常将它们应用于任何测试对象。为了测试PersonService，我宁愿使用包含两个测试示例的以下代码。

[TestClass]
public class UnitTest2
{
    private Mock<IRepository> moqRepository;
    private PersonService service;

    [TestInitialize]
    public void TestInitialize()
    {
        moqRepository = new Mock<IRepository>();
        service = new PersonService(moqRepository.Object);
    }

    [TestMethod]
    public void TestMethod3()
    {
        // arrange
        var persons = new List<Person>
        {
            new Person { Age = 0 },
            new Person { Age = 1 },
            new Person { Age = 17 },
            new Person { Age = 18 },
            new Person { Age = 19 },
            new Person { Age = 100 }
        };
        moqRepository
            .Setup(x => x.GetForExpression(It.IsAny<Expression<Func<Person, bool>>>()))
            .Returns<Expression<Func<Person, bool>>>(expr => persons.Where(expr.Compile()).ToList());

        // act
        var result = service.GetAllPersonsWith18More();

        // assert
        moqRepository.VerifyAll();
        result.Should().BeEquivalentTo(persons.Where(x => x.Age > 18));
    }

    [TestMethod]
    public void TestMethod4()
    {
        // arrange
        Expression<Func<Person, bool>> criteria = x => x.Age > 18;
        moqRepository
            .Setup(x => x.GetForExpression(It.IsAny<Expression<Func<Person, bool>>>()))
            .Returns(new List<Person>())
            .Callback<Expression<Func<Person, bool>>>(expr =>
            {
                var persons = new List<Person>
                {
                    new Person { Age = 0 },
                    new Person { Age = 1 },
                    new Person { Age = 17 },
                    new Person { Age = 18 },
                    new Person { Age = 19 },
                    new Person { Age = 100 }
                };
                persons.Where(expr.Compile()).Should().BeEquivalentTo(persons.Where(criteria.Compile()));
            });

        // act
        service.GetAllPersonsWith18More();

        // assert
        moqRepository.VerifyAll();
    }
}

为什么这个带有Expression <func <t，bool>的模拟不匹配？</func <t，bool>

3 个答案: