How to test my repositories implementation?

Question

I am using NUnit for test units. I have my interface on the domain so i am ready to make implementation of those interfaces in the persistence layer. My question is how do you actually make the unit tests for testing those repositories ? i believe this isnt a good idea to test directly from the database. Ive heard poeple that are using SQLite but it is okay to use mocks instead ? why are the poeple using SQLite for in-memory database when you can provide a mock with actuals entities ?

Any example would be welcome too.

Note: This is intended to be repositories coded in C# that gonna use NHibernate and Fluent NHibernate as mapping.

Thanks.

Answer 1

It of course depends, but in most cases I'd say it's generally enough to just mock the repositories in your tests and using the in-memory SQLite database only to test your mappings (FluentNHibernate Persistence specification testing).

For the NUnit mappings tests with SQLite I'm using the following base class:

public abstract class MappingsTestBase
{
    [SetUp]
    public void Setup()
    {
        _session = SessionFactory.OpenSession();
        BuildSchema(_session);
    }

    [TestFixtureTearDown]
    public void Terminate()
    {
        _session.Close();
        _session.Dispose();

        _session = null;
        _sessionFactory = null;
        _configuration = null;
    }

    #region NHibernate InMemory SQLite Session

    internal static ISession _session;

    private static ISessionFactory _sessionFactory;
    private static Configuration _configuration;

    private static ISessionFactory SessionFactory
    {
        get
        {
            if (_sessionFactory == null)
            {
                FluentConfiguration configuration = Fluently.Configure()
                    .Database(SQLiteConfiguration.Standard.InMemory().ShowSql)
                    .Mappings(m => m.FluentMappings
                        .AddFromAssemblyOf<NHibernateSession>())
                    .ExposeConfiguration(c => _configuration = c);

                _sessionFactory = configuration.BuildSessionFactory();
            }

            return _sessionFactory;
        }
    }

    private static void BuildSchema(ISession session)
    {
        SchemaExport export = new SchemaExport(_configuration);
        export.Execute(true, true, false, session.Connection, null);
    }

    #endregion
}

An example mappings test class deriving from the above base class could then look like the following:

[TestFixture]
public class MappingsTest : MappingsTestBase
{
    [Test]
    public void Persistence_Employee_ShouldMapCorrectly()
    {
        Category employee = new PersistenceSpecification<Employee>(_session)
            .CheckProperty(e => e.Id, 1)
            .CheckProperty(e => e.FirstName, "John")
            .CheckProperty(e => e.LastName, "Doe")
            .VerifyTheMappings();
        ...
        Assert.Equals(employee.FirstName, "John");
        ...
    }
}

Answer 2

Personally I'd do functional testing of the repositories against an actual database (possibly SQL Express). You could run those tests in CI only once a day.

All the unit tests for other classes can safely assume that the repositories work and use mock repositories.

EDIT: The above presumes that your repositories are solely used for data access; they basically just use LINQ or HQL. Keep the business logic out of them!