CODEWITHSUNDEEP
asp.net-mvcunit-testingmocking
WhiskerBiscuit
WhiskerBiscuit

Reputation: 5157

Unit testing a MVC controller

I'm trying to figure out the best way to build my unit tests for an MVC app. I created a simple model and interface, which is used by the controller constructors so that the testing framework (Nsubstitute) can pass a mocked version of the repository. This test passes, as expected.

My problem is now I want to take this a step further and test the file I/O operations in the "real" instantiation of IHomeRepository. This implementation should read a value from a file in the App_Data directory.

I've tried building a test without passing a mocked version of IHomeRepsotory in, however HttpContext.Current is null when I run my test.

Do I need to mock HttpContext? Am I even going about this in the right way?

//The model
public class VersionModel
{
    public String BuildNumber { get; set; }
}



//Interface defining the repository
public interface IHomeRepository
{
    VersionModel Version { get; }
}


//define the controller so the unit testing framework can pass in a mocked reposiotry.  The default constructor creates a real repository
public class HomeController : Controller
{

    public IHomeRepository HomeRepository;

    public HomeController()
    {
        HomeRepository = new HomeRepoRepository();
    }

    public HomeController(IHomeRepository homeRepository)
    {
        HomeRepository = homeRepository;
    }
.
.
.

}


class HomeRepoRepository : IHomeRepository
{
    private VersionModel _version;

    VersionModel IHomeRepository.Version
    {
        get
        {
            if (_version == null)
            {
                var absoluteFileLocation = HttpContext.Current.Server.MapPath("~/App_Data/repo.txt");
                if (absoluteFileLocation != null)
                {           
                    _version = new VersionModel() //read the values from file (not shown here)
                    {
                        BuildNumber = "value from file",
                    };
                }
                else
                {
                    throw new Exception("path is null");
                }
            }
            return _version;
        }
    }
}



[Fact]
public void Version()
{
    // Arrange
    var repo = Substitute.For<IHomeRepository>();  //using Nsubstitute, but could be any mock framework
    repo.Version.Returns(new VersionModel
    {
       BuildNumber = "1.2.3.4",
    });

    HomeController controller = new HomeController(repo);  //pass in the mocked repository

    // Act
    ViewResult result = controller.Version() as ViewResult;
    var m = (VersionModel)result.Model;

    // Assert
    Assert.True(!string.IsNullOrEmpty(m.Changeset));
}

Upvotes: 1

Views: 622

Answers (1)

Spock
Spock

Reputation: 6992

I believe you want test the real instantiation of IHomeRepository, which connects to a real database. In that case you need an App.config file, which specify the connection string. This is not a Unit test and it would an Integration Test. With HttpContext being null, you still can fake the HttpContext, retrieve real data from the database. See also here.

Upvotes: 1

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