unit test on exception

Question

I'm writing a unit test, where by I pass in a model and the title field in particular is required.

My test is as follows:

  [TestMethod]
    [ExpectedException(typeof(Exception), "Movie Title is mandatory")]
    public void Create()
    {
        var mc = new MoviesController();

        var model = new Movie
        {
            Cast = new[] { "Scott", "Joe", "mark" },
            Classification = "PG",
            Genre = null,
            MovieId = 0,
            Rating = 5,
            ReleaseDate = 2004,
            Title = null
        };

        var rep = mc.Create(model);
    }

Which calls this class via the controller:

public int Create(Movie movie)
    {
        int num;
        if (MovieRepository.Movies == null)
        {
            throw new Exception("Movies datasource is not available");
        }
        lock (MovieRepository._dsMovies)
        {
            DataRow str = MovieRepository._dsMovies.Tables["Movie"].NewRow();
            int num1 = MovieRepository._pk + 1;
            MovieRepository._pk = num1;
            int num2 = num1;
            movie.MovieId = num2;
            str["Id"] = num2;
            if (string.IsNullOrEmpty(movie.Title))
            {
                throw new Exception("Movie Title is mandatory");
            }
            str["Title"] = movie.Title.Trim();
            if (!string.IsNullOrEmpty(movie.Genre))
            {
                str["Genre"] = movie.Genre.Trim();
            }
            if (!string.IsNullOrEmpty(movie.Classification))
            {
                str["Classification"] = movie.Classification.ToString();
            }
            str["Rating"] = movie.Rating;
            str["ReleaseDate"] = movie.ReleaseDate;
            MovieRepository._dsMovies.Tables["Movie"].Rows.Add(str);
            if ((movie.Cast == null ? 0 : (int)((int)movie.Cast.Length > 0)) != 0)
            {
                this.AddCast(movie);
            }
            MovieRepository._dsMovies.AcceptChanges();
            num = num2;
        }
        return num;
    }

As you can see it checks for the title

if (string.IsNullOrEmpty(movie.Title))
        {
            throw new Exception("Movie Title is mandatory");
        }

Can I assert that exception? because as it stands after it fails I click on the output to check the fail log and I see this :

Test Name: CreateMovie

Test Outcome: Failed

Result Message: Test method Project.Test.UnitTest1.CreateMovie did not throw an exception. An exception was expected by attribute Microsoft.VisualStudio.TestTools.UnitTesting.ExpectedExceptionAttribute defined on the test method.

Result StandardOutput:

System.Exception: Movie Title is mandatory

at Movies.MovieRepository.Create(Movie movie)

at Project.Web.Controllers.MoviesController.Create(Movie movie) in c:\Users\Name\Documents\Visual Studio 2013\Projects\Project.Web\Project.Web\Controllers\MoviesController.cs:line 113

According to the result message it says it didn't throw an exception, when I know it did / should

Answer 1

You could wrap your unit test in a try catch, and put a debug point in the catch, so you can see it happening, and easily debug it:

[TestMethod]
[ExpectedException(typeof(Exception), "Movie Title is mandatory")]
public void Create()
{
    var mc = new MoviesController();

    var model = new Movie
    {
        Cast = new[] { "Scott", "Joe", "mark" },
        Classification = "PG",
        Genre = null,
        MovieId = 0,
        Rating = 5,
        ReleaseDate = 2004,
        Title = null
    };

    try
    {
        var rep = mc.Create(model);
        Assert.Fail("This shouldn't be shown, because the above should have thrown an exception ! !");
    }
    catch (Exception e)
    {
        Console.Out.WriteLine("AH ha! caught it ! :) : " + e);
        throw;
    }        
}

As an extra bonus, you can Assert.Fail so it won't get past it if it doesn't throw the exception.

As an even added bonus, you shouldn't be throwing an Exception but rather your own exception? maybe MovieException, so then you can catch specifically that exception.