Flyvergrillen

public class ClipRepository : IClipRepository
{
    IDataContext _dc;
    IDataContext dc
    {
        get
        {
            if (_dc == null)
            {
                _dc = new PiratDataContext();
            }
            return _dc;
        }
    }
    public IQueryable getClipsFromSite(int siteid)
    {
        return from sc in dc.SiteClips
        where sc.SiteID == siteid
        select sc.Clip;
    }
}

public interface IDataContext
{
    /// <summary>
    /// Gets the repository for the given type of entities
    /// </summary>
    /// <typeparam name="T">The type of the entity</typeparam>
    /// <returns>The repository of the given type</returns>
    IQueryable<t> GetTable<t>() where T : class, INotifyPropertyChanged;
 
    /// <summary>
    /// Adds a new entity to the repository
    /// </summary>
    /// <typeparam name="T">The type of the entity</typeparam>
    /// <param name="item">The entity to add</param>
    void Insert<t>(T item) where T : class, INotifyPropertyChanged;
 
    /// <summary>
    /// Deletes the specified entity from the repository
    /// </summary>
    /// <typeparam name="T">The type of the entity</typeparam>
    /// <param name="item">The entity to delete</param>
    void Delete<t>(T item) where T : class, INotifyPropertyChanged;
 
    /// <summary>
    /// Commits the changes to the repository
    /// </summary>
    void Save();
 
    /// <summary>
    /// Provides access to the modified objects tracked by the system
    /// </summary>
    ChangeSet GetChangeSet();
}

public class LinqToSqlDataContext<t_datacontexttype> : IDataContext where T_DataContextType : DataContext
{
    private DataContext _dc;
    private DataContext dc
    {
        get
        {
 
            if (_dc == null)
            {
                _dc = Activator.CreateInstance<t_datacontexttype>();
            }
            return _dc;
        }
    }
 
    public IQueryable<t> GetTable<t>() where T : class, INotifyPropertyChanged
    {
        return dc.GetTable(typeof(T)).Cast<t>();
    }
 
    public void Insert<t>(T item) where T : class, INotifyPropertyChanged
    {
        dc.GetTable(typeof(T)).InsertOnSubmit(item);
    }
 
    public void Delete<t>(T item) where T : class, INotifyPropertyChanged
    {
        dc.GetTable(typeof(T)).DeleteOnSubmit(item);
    }
 
    public void Save()
    {
        dc.SubmitChanges();
    }
 
    public ChangeSet GetChangeSet()
    {
        return dc.GetChangeSet();
    }
 
    #endregion
}

// creating the context
// in the ServiceLocators config, IDataContext is setup to return LinqToSqlDataContext<piratdatacontext>
_dc = ServiceLocator.New<idatacontext>();
 
// using it
return from sc in dc.GetTable<siteclip>()
         where sc.SiteID == siteid
         select sc.Clip;

public class MemoryDataContext : IDataContext
{
    private readonly List<object> _inMemoryDataStore = new List<object>();
    private readonly IList<object> _Inserts = new List<object>();
    private readonly IList<object> _Deletes = new List<object>();
    private readonly IList<object> _Updates = new List<object>();
 
    public MemoryDataContext()
    {
    }
 
    public MemoryDataContext(params INotifyPropertyChanged[] objects) : this()
    {
        foreach (var obj in objects)
        {
            _insert(obj);
        }
    }
 
    private void _insert(INotifyPropertyChanged item)
    {
        _inMemoryDataStore.Add(item);
        item.PropertyChanged += new PropertyChangedEventHandler((s,e) => _Updates.Add(s));
    }
 
    public IQueryable<t> GetTable<t>() where T : class, INotifyPropertyChanged
    {
        var list = from objects in _inMemoryDataStore
                    where typeof(T).IsAssignableFrom(objects.GetType())
                    select objects as T;
        return list.AsQueryable();
    }
 
    public void Insert<t>(T item) where T : class, INotifyPropertyChanged
    {
        _insert(item);
        _Inserts.Add(item);
    }
 
    public void Delete<t>(T item) where T : class, INotifyPropertyChanged
    {
        _inMemoryDataStore.Remove(item);
        _Deletes.Add(item);
    }
 
    public void Save()
    {
        if (Completed != null)
        {
            Completed(this, EventArgs.Empty);
        }
    }
 
    public ChangeSet GetChangeSet()
    {
        var constructor = typeof(ChangeSet).GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic).First();
        var changes = constructor.Invoke(new object[]
        {
            new ReadOnlyCollection<object>(_Inserts),
            new ReadOnlyCollection<object>(_Deletes),
            new ReadOnlyCollection<object>(_Updates),
        }) as ChangeSet;
 
        return changes;
    }
 
    public event EventHandler Completed;
}

        [TestInitialize]
        public void init()
        {
            var memContext = new MemoryDataContext();
            memContext.Insert(new Clip { ID = 1, Title = "hest" });
            memContext.Insert(new Clip { ID = 2, Title = "giraf" });
            memContext.Insert(new Clip { ID = 3, Title = "tobis" });
            memContext.Insert(new Clip { ID = 4, Title = "laks", AllowExternalEmbedding = true });
            memContext.Insert(new SiteClip { ClipID = 1, SiteID = 50 });
            memContext.Insert(new SiteClip { ClipID = 2, SiteID = 50 });
            memContext.Insert(new SiteClip { ClipID = 3, SiteID = 4 });
            memContext.Insert(new SiteClip { ClipID = 4, SiteID = 4 });
            memContext.Insert(new SiteClip { ClipID = 4, SiteID = 50 });
 
            ServiceLocator.Add(typeof(IDataContext), memContext);
        }
 
        [TestMethod]
        public void getClipsFromSiteTest()
        {
            ClipRepository target = new ClipRepository();
            Assert.AreEqual(3, target.getClipsFromSite(50).Count());
            Assert.AreEqual(2, target.getClipsFromSite(4).Count());
            Assert.AreEqual(0, target.getClipsFromSite(1).Count());
        }
    }