How do you transfer the execution of a Expression created by an IQueryable object to a IEnumerable ?

Question

In my code I'd like to make my repositories IQueryable. This way, the criteria for selection will be a linq expression tree.

Now if I want to mock my repository in theorie this is very easy : just implement the interface of my repository (which is also a IQueryable object).

My mock repository implementation would be only a in memory collection, but my question is : Do you know an easy way to implement the IQueryable interface of my mock, to transfer the query to my in-memory collection (IEnumerable) ?

Thanks for your response,

Some precision

The client object of my repository will use my repository this way :

var result = from entry in MyRepository where entry.Product == "SomeProduct" select entry;

What does ToList or AsEnumerable is to execute the query and return the result as a List or as a IEnumerable. But I have to implement the IQueryable interface on my repository, with a IQueryProvider which transform the expression in a call to a IEnumerable object.

Solution

The implementation of the solution is delegating call to IQueryable to my inmemory collection with AsQueryable.

public class MockRepository : IQueryable<DomainObject>
    {
     private List<DomainObject> inMemoryList = new List<DomainObject>();

     #region IEnumerable<DomainObject> Members

     public IEnumerator<DomainObject> GetEnumerator()
     {
      return inMemoryList.GetEnumerator();
     }

     #endregion

     #region IEnumerable Members

     IEnumerator IEnumerable.GetEnumerator()
     {
      return inMemoryList.GetEnumerator();
     }

     #endregion

     #region IQueryable Members

     public Type ElementType
     {
      get
      {
       return inMemoryList.AsQueryable().ElementType;
      }
     }

     public Expression Expression
     {
      get
      {
       return inMemoryList.AsQueryable().Expression;
      }
     }

     public IQueryProvider Provider
     {
      get
      {
       return inMemoryList.AsQueryable().Provider;
      }
     }

     #endregion
    }

Answer 1

Can you use the extension method

.ToList<>

Answer 2

Use AsQueryable on your mocks. Now they're queryable and you can treat them like any other queryable.