Anchor ActiveModel::Naming to top level namespace.

Author: thomas-holmes

lib/rspec/active_model/mocks/mocks.rb

@@ -88,15 +88,15 @@ def mock_model(string_or_model_class, stubs = {})
           model_class = Object.const_get(string_or_model_class)
         else
           model_class = Object.const_set(string_or_model_class, Class.new do
-            extend ActiveModel::Naming
+            extend ::ActiveModel::Naming
             def self.primary_key; :id; end
           end)
         end
       else
         model_class = string_or_model_class
       end
 
-      unless model_class.kind_of? ActiveModel::Naming
+      unless model_class.kind_of? ::ActiveModel::Naming
         raise ArgumentError.new <<-EOM
 The mock_model method can only accept as its first argument:
 * A String representing a Class that does not exist