Fix the intermittent test: missing attribute:: scope 1

Reset all cached information about columns after defining the model to prevent old columns from leaking for other tests.

e.g.: https://travis-ci.org/thoughtbot/shoulda-matchers/jobs/622356910

spec/support/unit/helpers/model_builder.rb

@@ -71,6 +71,7 @@ def define_model(name, columns = {}, options = {}, &block)
           options,
           &block
         )
+        model.reset_column_information
         defined_models << model
         model
       end
@@ -87,10 +88,6 @@ def clear_column_caches
           DevelopmentRecord.connection_pool.clear_cache!
           ProductionRecord.connection_pool.clear_cache!
         end
-
-        defined_models.each do |model|
-          model.reset_column_information
-        end
       end
 
       def drop_created_tables