How to create an instance of the EntityDescriptor class

For testing purposes I need to create an instance of the EntityDescriptor class. This cannot be done directly, cause the constructor is not public.

That's why I try use reflection to create the instance.

EdmModel model = new EdmModel();
var constructors = typeof(EntityDescriptor).GetConstructors(System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var entityDescripto = constructors[0].Invoke(new object[] { model }) as EntityDescriptor;

I know, that the single constructor of the class takes one argument of type EdmModel. But when I call the above code I the following exception:

System.ArgumentException : Das Objekt mit dem Typ "Microsoft.Data.Edm.Library.EdmModel" kann nicht in den Typ "System.Data.Services.Client.ClientEdmModel" konvertiert werden.

But I cannot find anywhere the class ClientEdmModel. Does anybody has an idea?