How to fake DbContext.Entry method in Entity Framework with repository pattern c# entity-framework repository-pattern unit-testing


Because I want to unit test my code I have implemented the repository pattern in my MVC4 application. I managed to make a Context Interface, a fake Context and use a fake implementation of a System.Data.Entity.DbSet by following this code.

Unfortunately, just like two posters before me (here and here), I do not manage to mock the DbContext.Entry method. I use this method for updating database entries in my code as follows:

DbContext.Entry(order).State = EntityState.Modified;

I have not found a solution to this problem, only people who say things like:

"and what is the point of unit testing this code? You fake the Find method, then you fake DbEntityEntry and there will be no real logic to test."

or to

read this and all linked questions before you continue. (...) If you want to test your repositories create integration tests talking to the real database.

That is all good and well but still no answer to the question. I read the critique and I still do want this Entry method so I will be able to use a fake context and use mock objects in my unit test. Of course I will use integration tests as well but they are not nearly as fast as some quick unit tests.

The error I receive when I try some implementations is that Error 2 'Project.Models.Order' does not contain a definition for 'State' and no extension method 'State' accepting a first argument of type '[whatever return type I use]' could be found (are you missing a using directive or an assembly reference?)

I hope someone can help me make a fake DbContext.Entry method.

5/23/2017 12:02:02 PM

Accepted Answer

Found the answer here by "adding additional level of indirection" we get:

public void SetModified(object entity)
    Entry(entity).State = EntityState.Modified;

and use DbContext.SetModified(entity) in our controller.

5/23/2017 12:09:42 PM

Popular Answer

To get around this I added a method overload, and added an obsolete attribute to see where the original method was being called.

    public virtual void Entry<TEntity>(TEntity entity, Action<DbEntityEntry<TEntity>> action) where TEntity : class

    [Obsolete("Use overload for unit tests.")]
    public new DbEntityEntry<TEntity> Entry<TEntity>(TEntity entity) where TEntity : class
        return base.Entry(entity);

        /** or **/

        throw new ApplicationException("Use overload for unit tests.");

then you can DbContext.Entry(order, ent => ent.State = EntityState.Modified;

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