Unit Testing with the Dynamics CRM ServiceContext

One of the nice things in Dynamics CRM 2011 and in a similar way in CRM4.0 with Sdk 13 is the ability to query CRM data using LINQ.

The centerpiece for this feature is the ServiceContext. This allows you to do a query using LINQ.

Now when it comes to unit testing the code the ServiceContext is a pain.

What I wanted to do is to be able to define the data, the ServiceContext queries on, while not being connected to CRM.

So, I needed a way to redirect the ServiceContext to a List.

Searching through documentation I found the overridable

protected IQueryable<TEntity> CreateQuery<TEntity>(IQueryProvider provider, string entityLogicalName)

method. This is a factory method that than uses the query provider to query the data.

Now I extend the ServiceContext class and override the CreateQuery method:

public class TestServiceContext : ServiceContext
{
    public ICollection<Entity> Data { get; private set; }

    public TestServiceContext(IOrganizationService service, ICollection<Entity> data) : base(service)
    {
        Data = data;
    }

    [SuppressMessage("Microsoft.Design", "CA1004", Justification = "Design cannot be changed, as method signature is provided by Xrm OrganizationServiceContext")]
    protected override IQueryable<TEntity> CreateQuery<TEntity>(IQueryProvider provider, string entityLogicalName)
    {
        return Data.OfType<TEntity>().Where(data => { var entityData = data as Entity;
            if (entityData != null)
                return entityData.LogicalName == entityLogicalName;
            else
                return false;}).AsQueryable();
    }
}

Basically there can be two cases that have to be reckoned with:

• Queries created using ServiceContext.CreateQuery<Account>()
  
• Queries created using ServiceContext.CreateQuery(Account.LogicalName)

That’s why we reduce the returned data set to those OfType<TEntity> and then query it down to those entities having the specified logical name.

Using this implementation of TestServiceContext now actually queries on the Data collection.

Now you should have a Factory that creates your ServiceContext in your code, using a Mocking library you can then return the TestServiceContext when calling the factory.

I will show a use case and a test in the next couple of days.