Using Moq to mock a repository that returns a value

Question

How do I set up my test method on that mocks a repository which accepts an object?

This is what I have so far:

Service.cs

    public int AddCountry(string countryName)
    {
        Country country = new Country();
        country.CountryName = countryName;
        return geographicsRepository.SaveCountry(country).CountryId;
    }

test.cs

    [Test]
    public void Insert_Country()
    {
        //Setup
        var geographicsRepository = new Mock<IGeographicRepository>();

        geographicsRepository.Setup(x => x.SaveCountry(It.Is<Country>(c => c.CountryName == "Jamaica"))); //How do I return a 1 here?

        GeographicService geoService = new GeographicService(geographicsRepository.Object);

        int id = geoService.AddCountry("Jamaica");

        Assert.AreEqual(1, id);
    }

SaveCountry(Country country); returns an int.

I need to do 2 things:

1. First test, I need to tell the setup to return an int of 1.

2. I need to create a second test Insert_Duplicate_Country_Throws_Exception(). In my Setup, how do I tell the repository to throw an error when I do:

   int id = geoService.AddCountry("Jamaica");
   int id = geoService.AddCountry("Jamaica");
   

Framework:

1. NUnit.
2. Moq.
3. ASP.NET MVC - repository pattern.

Answer 1

Your first test should look something like this:

[Test]
public void Insert_Country()
{
    Mock<IGeographicRepository> geographicsRepository = new Mock<IGeographicRepository>();
    GeographicService geoService = new GeographicService(geographicsRepository.Object);

    // Setup Mock
    geographicsRepository
        .Setup(x => x.SaveCountry(It.IsAny<Country>()))
        .Returns(1);

    var id = geoService.AddCountry("Jamaica");

    Assert.IsInstanceOf<Int32>(id);
    Assert.AreEqual(1, id);
    geographicsRepository.VerifyAll();
}

The second test should look like this:

[Test]
public void Insert_Duplicate_Country_Throws_Exception()
{
    Mock<IGeographicRepository> geographicsRepository = new Mock<IGeographicRepository>();
    GeographicService geoService = new GeographicService(geographicsRepository.Object);

    // Setup Mock
    geographicsRepository
        .Setup(x => x.SaveCountry(It.IsAny<Country>()))
        .Throws(new MyException());

    try
    {
        var id = geoService.AddCountry("Jamaica");
        Assert.Fail("Exception not thrown");
    }
    catch (MyException)
    {
        geographicsRepository.VerifyAll();
    }
}