Using NUnit to test a list of items

Tell me if my concept is wrong. I have 2 classes; Country and State. A state will have a CountryId property.

I have a service and a repository as follows:

Service.cs

    public LazyList<State> GetStatesInCountry(int countryId)
    {
        return new LazyList<State>(geographicsRepository.GetStates().Where(s => s.CountryId == countryId));
    }

IRepository.cs

public interface IGeographicRepository
{
    IQueryable<Country> GetCountries();

    Country SaveCountry(Country country);

    IQueryable<State> GetStates();

    State SaveState(State state);
}

MyTest.cs

    private IQueryable<State> getStates()
    {
        List<State> states = new List<State>();
        states.Add(new State(1, 1, "Manchester"));//params are: StateId, CountryId and StateName
        states.Add(new State(2, 1, "St. Elizabeth"));
        states.Add(new State(2, 2, "St. Lucy"));
        return states.AsQueryable();
    }

    [Test]
    p开发者_JAVA技巧ublic void Can_Get_List_Of_States_In_Country()
    {

        const int countryId = 1;
        //Setup
        geographicsRepository.Setup(x => x.GetStates()).Returns(getStates());

        //Call
        var states = geoService.GetStatesInCountry(countryId);

        //Assert
        Assert.IsInstanceOf<LazyList<State>>(states);
        //How do I write an Assert here to check that the states returned has CountryId = countryId?
        geographicsRepository.VerifyAll();
    }

I need to verify the information of the states returned. Do I need to write a loop and put the asserts in it?

Assert.IsTrue(states.All(x => 1 == x.CountryId));

I don't know if there is something in nunit for this, but you could do this with linq:

    states.All(c => Assert.AreEqual(1, c.CountryId))

EDIT after quick googling it seems you can do this

Assert.That(states.Select(c => c.CountryId), Is.All.EqualTo(1));