c# - 使用 Moq 更新、删除单元测试的方法

Question

我在我的单元测试中使用了 Moq 框架。这是 UpdateApplication 测试方法:

[TestMethod]
public void UpdateApplication()
{
    const string newAplpicationName = "NewApplication1";

    var data =
        new[]
        {
            new Application { Id = 1, Name = "Application1" }, new Application { Id = 2, Name = "Application2" },
            new Application { Id = 3, Name = "Application3" }, new Application { Id = 4, Name = "Application4" }
        }
            .AsQueryable();

    var mockSet = new Mock<DbSet<Application>>();
    mockSet.As<IQueryable<Application>>().Setup(m => m.Provider).Returns(data.Provider);
    mockSet.As<IQueryable<Application>>().Setup(m => m.Expression).Returns(data.Expression);
    mockSet.As<IQueryable<Application>>().Setup(m => m.ElementType).Returns(data.ElementType);
    mockSet.As<IQueryable<Application>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

    mockSet.Setup(m => m.AddOrUpdate(It.IsAny<Application[]>())).Callback(
        (Application[] apps) =>
        {
            apps.FirstOrDefault(m => m.Id == 1).Name = newAplpicationName;
        }).Verifiable(); // <-- Exception

    var mockContext = new Mock<AppDbContext>();
    mockContext.Setup(c => c.Applications).Returns(mockSet.Object);

    // Act 
    var commandHandler = new UpdateApplicationCommandHandler(mockContext.Object);
    var commandArg = new ApplicationCommandArg { Id = 1, Name = newAplpicationName };
    commandHandler.Execute(new UpdateApplicationCommand(commandArg));

    // Verify
    mockContext.Verify(m => m.SaveChanges(), Times.Once());
}

运行测试时出现异常:

An exception of type 'System.NotSupportedException' occurred in Moq.dll but wasnot handled in user codeAdditional information: Expression references a method that does not belong tothe mocked object: m => m.AddOrUpdate(It.IsAny())   at Moq.Mock.ThrowIfNotMember(Expression setup, MethodInfo method)   at Moq.Mock.c__DisplayClass19`1.b__18()   at Moq.PexProtector.Invoke[T](Func`1 function)   at Moq.Mock.Setup[T](Mock`1 mock, Expression`1 expression, Condition condition)   at Moq.Mock`1.Setup(Expression`1 expression)   at UpdateApplication() in UpdateApplicationCommandTests.cs:line 39

我应该如何使用 Moq 为更新和删除操作编写单元测试？

Answer 1

这种 UpdateApplication 单元测试方法的变体对我有用，但我不确定它是否正确:

    [TestMethod]
    public void UpdateApplication()
    {
        const string newAplpicationName = "NewApplication1";

        var data =
            new[]
            {
                new Application { Id = 1, Name = "Application1" }, new Application { Id = 2, Name = "Application2" },
                new Application { Id = 3, Name = "Application3" }, new Application { Id = 4, Name = "Application4" }
            }
                .AsQueryable();

        var mockSet = new Mock<DbSet<Application>>();
        mockSet.As<IQueryable<Application>>().Setup(m => m.Provider).Returns(data.Provider);
        mockSet.As<IQueryable<Application>>().Setup(m => m.Expression).Returns(data.Expression);
        mockSet.As<IQueryable<Application>>().Setup(m => m.ElementType).Returns(data.ElementType);
        mockSet.As<IQueryable<Application>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

        var mockContext = new Mock<AppDbContext>();
        mockContext.Setup(m => m.Applications).Returns(mockSet.Object);


        // Act 
        var commandHandler = new UpdateApplicationCommandHandler(mockContext.Object);
        var commandArg = new ApplicationCommandArg { Id = 1, Name = newAplpicationName };
        commandHandler.Execute(new UpdateApplicationCommand(commandArg));

        Assert.AreEqual(newAplpicationName, data.First(m => m.Id == 1).Name);

        mockContext.Verify(m => m.SaveChanges(), Times.Once());
    }

但是我的 DeleteApplicationCommandTest 仍然有问题。当我运行测试时，我得到一个异常“预期对模拟的调用恰好 3 次，但是是 2 次:m => m.Applications”。这是测试方法:

    [TestMethod]
    public void DeleteApplication()
    {
        var data =
            new[]
            {
                new Application { Id = 1, Name = "Application1" }, new Application { Id = 2, Name = "Application2" },
                new Application { Id = 3, Name = "Application3" }, new Application { Id = 4, Name = "Application4" }
            }
                .AsQueryable();

        var mockSet = new Mock<DbSet<Application>>();
        mockSet.As<IQueryable<Application>>().Setup(m => m.Provider).Returns(data.Provider);
        mockSet.As<IQueryable<Application>>().Setup(m => m.Expression).Returns(data.Expression);
        mockSet.As<IQueryable<Application>>().Setup(m => m.ElementType).Returns(data.ElementType);
        mockSet.As<IQueryable<Application>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

        var mockContext = new Mock<AppDbContext>();
        mockContext.Setup(m => m.Applications).Returns(mockSet.Object);

        // Act 
        var commandHandler = new DeleteApplicationCommandHandler(mockContext.Object);
        var commandArg = new ApplicationCommandArg { Id = 1 };
        commandHandler.Execute(new DeleteApplicationCommand(commandArg));

        // Verify
        mockSet.Verify(m => m.Remove(It.IsAny<Application>()), Times.Once());
        mockContext.Verify(m => m.SaveChanges(), Times.Once());
        mockContext.VerifyGet(m => m.Applications, Times.Exactly(3));
    }

这是我的 DeleteApplicationCommandHandler 的执行方法:

    public override void Execute(DeleteApplicationCommand command)
    {
        Debug.WriteLine("DeleteApplicationCommand executed");

        var application = this.DbContext.Applications.FirstOrDefault(m => m.Id == command.CommandArg.Id);

        if (application == null)
        {
            throw new Exception(string.Format("Application with id {0} was not found", command.CommandArg.Id));
        }

        this.DbContext.Applications.Remove(application);

        this.DbContext.SaveChanges();
    }

为什么 DeleteApplication 测试方法失败？