Using MVC3 and EF4, how can one adequately test functionality that relies on a round trip to the database to create IDENTITY values?

I have a scenario where the code under test inserts a record into a database, then attempts to retrieve it back from the database using its primary key.

This happens over a series of records in the same method.

I am mocking my ObjectContext and ObjectSets, so the current result is that each record "inserted" into my FakeObjectSet is given a primary key of 0.

In the case where I am only inserting a single record and asserting the record exists, this is fine...but when I am inserting multiple and my workflow requires retrieving speci开发者_运维技巧fic records by primary key, my queries return multiple results since all inserts have a primary key of 0.

Any ideas?

You can add an event to your FakeObjectSet<T> that will be raised when AddObject is called. Then in your test, add an event handler to set the Id of the object being added.

For example, a simplified version of a fake object set:

public class ObjectAddedEventArgs<T> : EventArgs
{
    public T Item { get; set; }
}

public class FakeObjectSet<T>
{
    private List<T> _list = new List<T>();

    public event EventHandler<ObjectAddedEventArgs<T>> ObjectAdded;

    public void AddObject(T item)
    {
        _list.Add(item);
        OnObjectAdded(item);
    }

    protected virtual void OnObjectAdded(T item)
    {
        EventHandler<ObjectAddedEventArgs<T>> h = AddingItem;
        if (h != null)
        {
            h(this, new ObjectAddedEventArgs<T> { Item = item });
        }
    }

    // other methods...
}

And in your test, when you want to set an incrementing Id value, add a handler to your FakeObjectSet<T> and update the object's Id:

int id = 0;

FakeObjectSet<Foo> set = new FakeObjectSet<Foo>();
set.ObjectAdded += (s, e) => { e.Item.Id = id++; };

Your mock repository could retrieve the id from an id generator (simple counter), that increments with each consecutive call.

I should stub the return values from the database and so on I will by myself decide what primary keys each object will have.

What is your goal for the tests?