Mock Method call from another Method using Moq

Question

I am trying to create Unit test for below two methods using MsTest. I am fairly new to this, and so far have referred to different posts on the Topic.

Code Requirement

Create a Timer Based Function (Azure)
Execute Method 1 and Method 2 in the order to get the Output.

Test Requirement

Ability to be able to create Unit test cases for each Class/Method with no external dependency (Fake/Mock)
To Fit this Code under Test can be update as code is not yet Live.
Open to other tools/Nugets beyond Moq to support the Test requirement.

When I try to run the Unit test, it does not mock Method 2 instead executes it. I need help in debugging the code.

 public class Job: IJob
 {
    //Method 1
    public List<TableEntity> GetJob()
    {
        var a = Get<T>("static value"); //Mock this to Test Method GetJob
        return a.Result;
    }

   //Method 2
    public async Task<List<T>> Get<T>(string tableName) where T : ITableEntity, new()
    {
        var t = new List<T>();
        //add data to T
        return t;

    }
}

Interface

public interface IJob
{
    List<TableEntity> GetJob();

    Task<List<T>> Get<T>(string tableName) where T : ITableEntity, new();

}

Test Code

    private readonly Mock<IJob> _mockIJob = new Mock<IJob>();
    readonly Job _job = new Job();

    public void NotThrow_Error_When_JobFound()
    {
        //Arrange
        var jobs = new J.TableEntity()
        {
            FolderName = "FolderName",
            Timestamp = DateTimeOffset.Now
        };

        var jobList = Task.FromResult(new List<TableEntity>() { jobs });
        
        _mockIJob.Setup(c => c.Get<TableEntity>(""))
                .Returns(jobList);

        //Act
        var actualResult = _job.GetJob();

        //Assert
        Assert.AreEqual(jobList, actualResult);

    }

Thanks @RajkumarM, however, I think I cannot use dependency injection due to the fact that Method 1 is an Azure Function Class — s s
– s s, Commented Oct 22, 2022 at 20:21

Can Bilgin · Accepted Answer · 2022-10-25 08:55:59Z

I think when simplifying the code some things got lost in translation (e.g, var a = Get<T>("static value"); no idea what T refers here) but with small modifications I think you would be able to achieve what you are trying.

In order for the mock to be used you need the mocked object instance so you will need to remove reference to concrete instance:

    private readonly Mock<IJob> _mockIJob = new Mock<IJob>();
    // readonly Job _job = new Job(); // This should not be used.

In order to use a concrete method1 with the mocked method2, you will need to mock the Job concrete class.

private readonly Mock<Job> _mockJob = new Mock<Job>();

In order for the proxy class to "take over" a method it should be declared as virtual:

//Method 2
public virtual List<T> Get<T>(string tableName) where T : TableEntity, new()
{
    var t = new List<T>();
    //add data to T
    return t;

}

While mocking the method you should use the It.IsAny<string>() specification otherwise your test method is using a mock with "" parameter whereas the method1 is using "static value" parameter, so it will not match the proxy method.

so putting this all together:

private readonly Mock<Job> _mockJob = new Mock<Job>();

[Fact]
public void NotThrow_Error_When_JobFound()
{
    //Arrange
    var jobs = new TableEntity()
    {
        FolderName = "FolderName",
        Timestamp = DateTimeOffset.Now
    };

    var jobList = new List<TableEntity>() { jobs };

    _mockJob.Setup(c => 
            c.Get<TableEntity>(It.IsAny<string>()))
        .Returns(() =>
        {
            // easier to visualize the breakpoint.
            return jobList;
        });

    //Act
    var actualResult = _mockJob.Object.GetJob();

    //Assert
    Assert.Equal(jobList, actualResult);
}

Hope it helps.

Thanks, This works for me. You are right T in Get<T> corresponds to a custom class that inherits from ITableEntity. I was not sure if a method can be mocked, always thought is possible alone for the interface.

SzybkiDanny · Accepted Answer · 2022-10-22 23:56:37Z

0

It will not be possible the way you approach it. What you are attempting is to execute a test on an instance of a concrete class and, at the same time, to mock the instance.

I am not going to deliberate on whether GetJob method should exist in the current class or be moved elsewhere. For the solution in the current form the simplest way to achieve testability (and perhaps reduce duplication in the future) would be by declaring GetJob as extension method on IJob interface:

public static class IJobExtensions
{
    public static List<TableEntity> GetJob(this IJob job)
    {
        var a = job.Get<T>("static value"); //Mock this to Test Method GetJob
        return a.Result;
    }
}

The unit test would then look like this:

private readonly Mock<IJob> _mockIJob = new Mock<IJob>();

public void NotThrow_Error_When_JobFound()
{
    //Arrange
    var jobs = new J.TableEntity()
    {
        FolderName = "FolderName",
        Timestamp = DateTimeOffset.Now
    };

    var jobList = Task.FromResult(new List<TableEntity>() { jobs });
    
    _mockIJob.Setup(c => c.Get<TableEntity>(""))
            .Returns(jobList);

    //Act
    var actualResult = _mockIJob.Object.GetJob();

    //Assert
    Assert.AreEqual(jobList, actualResult);
}

answered Oct 22, 2022 at 23:56

SzybkiDanny

2934 silver badges13 bronze badges

1 Comment

s s Over a year ago

Thanks, I added additional details to the original post as Dev/Test Requirements so as to give a bit of background. Also, I tried to use the code as suggested, however I think it has two attention points 1. With suggested implementation, Method 1 is unreachable (used debugger) and response is returned from Interface Extension 2. Response thus returned is NULL as Result object is NULL

Peter Csala · Accepted Answer · 2022-10-28 07:39:40Z

0

If I understand your problem correctly then you are looking for partial mocking. You want to use GetJob as it is but you want to mock Get<T>.

Prerequisite

The Get<T> should be marked as virtual to be able to mock it.

Test

//Arrange
...
var jobPartialMock = new Mock<Job>();
jobPartialMock.CallBase = true; //Use GetJob as it is
jobPartialMock
   .Setup(job => job.Get<TableEntity>(It.IsAny<string>()))
   .ReturnsAsync(new List<TableEntity>() { jobs }); // Mock `Get<T>`

//Act
var actual = jobPartialMock.Object.GetJob();

//Assert
...

edited Oct 28, 2022 at 7:39

answered Oct 25, 2022 at 8:44

Peter Csala

23.7k16 gold badges51 silver badges96 bronze badges

4 Comments

s s Over a year ago

Yes, I am indeed looking to mock a method being called from another method. I have also tried this and it also works. Suggestion from @Can Bilgin also works and seems to be with little more explanation.

Peter Csala Over a year ago

@ss What sort of explanation are you missing? Which line is unclear?

s s Over a year ago

How does var jobPartialMock = new Mock<Job>(); works , Thought Moq is only possible for interfaces. Does it acts as an override?

Peter Csala Over a year ago

@ss I've added a link which describes in great detail how does partial mocking work in Moq. Is it enough or shall I extend my answer with further clarification?

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