Update, Delete unit test's methods using Moq

Question

I am using the Moq framework in my Unit Test. This is the UpdateApplication test method:

[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());
}

I got an exception when ran the test:

An exception of type 'System.NotSupportedException' occurred in Moq.dll but was
not handled in user code

Additional information: Expression references a method that does not belong to
the 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

How should I write unit tests for update and delete actions using Moq?

http://stackoverflow.com/questions/2295960/mocking-extension-methods-with-moq — Daniel Dušek, Dec 01 '14 at 16:36

Vitone · Answer 1 · 2014-12-02T08:38:45.040

This variant of UpdateApplication unit test method is working for me but I am not sure if it is correct:

    [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());
    }

But I still have a problem with my DeleteApplicationCommandTest. When I run the test I get an excepton "Expected invocation on the mock exactly 3 times, but was 2 times: m => m.Applications". This is test method:

    [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));
    }

This is my Execute method of DeleteApplicationCommandHandler:

    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();
    }

Why DeleteApplication test method fails?

score 1 · Answer 2 · edited May 23 '17 at 12:00

1

The problem is that AddOrUpdate is an extension method. Moq cannot mock extension methods, so you'll need to find another way to achieve your test coverage.

edited May 23 '17 at 12:00

Community

1
1

answered Dec 01 '14 at 16:03

Patrick Quirk

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Update, Delete unit test's methods using Moq

2 Answers2