如何验证使用正确表达式调用的模拟异步方法？

Question

我已经使用XUnit和Moq编写了一些测试。模拟接口实现的一种方法是接受类型为Expression<Func<T, bool>>的参数。一切似乎都运行良好但我无法理解验证方法是否使用正确的表达式调用的工作。

鉴于以下测试，即使调用看起来正确，该方法也不会返回设置中指定的值：

    /// <summary>
    /// Verify that a create fails appropriately when another entity was found given the same name,
    /// Verify that the message of the exception contains the duplicate name
    /// Verify that update fails before other calls are made
    /// </summary>
    [Theory(DisplayName = "Definition Types service - Create")]
    [MemberData(nameof(DefinitionTypesTestData.SingleDefinitionType), MemberType = typeof(DefinitionTypesTestData))]
    public async Task CreateDefinitionTypeShouldThrowDuplicateTest(DefinitionType obj)
    {
        if (obj == null) throw new NullReferenceException($"Test data was null in theory 'Definition Types service - Create'");
        var crudService = new Mock<IEntityCrudService<DefinitionType>>();
        crudService.Setup(crud => crud.GetEntitiesAsync(x => x.Name == obj.Name))
            .Returns(Task.FromResult<IEnumerable<DefinitionType>>(new List<DefinitionType> {
            new DefinitionType {
                Name = "Test",
                Description = "Test",
                DisplayName = "Test",
                ID = Guid.NewGuid()
            } }));
        IDefinitionTypesService serviceUnderTest = new DefinitionTypesService(crudService.Object);
        var exception = await Assert.ThrowsAsync<EntityDuplicationException>(() => serviceUnderTest.InsertDefinitionTypeAsync(obj));
        Assert.Contains("Definition type", exception.DisplayMessage);
        Assert.Contains(obj.Name, exception.DisplayMessage);
        crudService.Verify(crud => crud.GetEntitiesAsync(x => x.Name == obj.Name), Times.Once);
        crudService.VerifyNoOtherCalls();
    }

我有InsertDefinitionType（DefinitionType obj）的以下实现：

async Task IDefinitionTypesService.InsertDefinitionTypeAsync(DefinitionType obj)
    {
        var definitiontypes = await _definitionTypeService.GetEntitiesAsync(x => x.Name == obj.Name);

        if(definitiontypes.Any())
        {
            throw new EntityDuplicationException("Definition type", name: obj.Name);
        }

        try
        {
            await _definitionTypeService.CreateAsync(obj);
        }
        catch (EntityNotSavedException exc)
        {
            exc.EntityType = "Definition type";
            throw exc;
        }
    }

当我按照以下方式更改设置时，我确实得到了结果，但在我的验证函数中，它表示函数永远不会被调用（或者至少使用给定的表达式）。 ：

crudService.Setup(crud => crud.GetEntitiesAsync(It.IsAny<Expression<Func<DefinitionType, bool>>>()))
    .Returns(Task.FromResult<IEnumerable<DefinitionType>>(new List<DefinitionType> {
        new DefinitionType {
            Name = "Test",
            Description = "Test",
            DisplayName = "Test",
            ID = Guid.NewGuid()
        } }));

现在我还将验证更改为更通用：

crudService.Verify(crud => crud.GetEntitiesAsync(It.IsAny<Expression<Func<DefinitionType, bool>>>()), Times.Once);

现在我的测试通过，但我真的想验证方法被正确调用而不是被调用。我如何以最简单/最好的方式解决这个问题？

Answer 1

您需要更具体地说明设置中使用的表达式。

使用It.Is<T>()并调用表达式进行设置和验证。

[Theory(DisplayName = "Definition Types service - Create")]
[MemberData(nameof(DefinitionTypesTestData.SingleDefinitionType), MemberType = typeof(DefinitionTypesTestData))]
public async Task CreateDefinitionTypeShouldThrowDuplicateTest(DefinitionType obj) {

    if (obj == null) throw new NullReferenceException($"Test data was null in theory 'Definition Types service - Create'");

    //Arrange
    var crudService = new Mock<IEntityCrudService<DefinitionType>>();

    var list = new List<DefinitionType>() {
        new DefinitionType {
            Name = "Test",
            Description = "Test",
            DisplayName = "Test",
            ID = Guid.NewGuid()
        }
    };

    crudService
        .Setup(_ => _.GetEntitiesAsync(It.Is<Expression<Func<DefinitionType, bool>>>(exp => exp.Compile()(obj))))
        .ReturnsAsync(list);

    IDefinitionTypesService serviceUnderTest = new DefinitionTypesService(crudService.Object);

    //Act
    var exception = await Assert.ThrowsAsync<EntityDuplicationException>(() => serviceUnderTest.InsertDefinitionTypeAsync(obj));

    //Assert
    Assert.Contains("Definition type", exception.DisplayMessage);
    Assert.Contains(obj.Name, exception.DisplayMessage);
    crudService.Verify(_ => _.GetEntitiesAsync(It.Is<Expression<Func<DefinitionType, bool>>>(exp => exp.Compile()(obj))), Times.Once);
    crudService.VerifyNoOtherCalls();
}

请特别注意设置和验证中使用的表达式。

_ => _.GetEntitiesAsync(It.Is<Expression<Func<DefinitionType, bool>>>(exp => exp.Compile()(obj)))