Clear schema cache after each test

When running unit tests in a random order, some tests may fail as the
columns hash within a model may not be in sync with the database. This
is because the columns hash is cached outside of the model, so removing
the model from the object space and then recreating that model won't
clear the columns hash.

spec/support/unit/helpers/class_builder.rb

@@ -60,10 +60,6 @@ module UnitTests
         if block_given?
           constant.class_eval(&block)
         end
-
-        if constant.respond_to?(:reset_column_information)
-          constant.reset_column_information
-        end
       end
     end
 
@@ -72,9 +68,5 @@ module UnitTests
     def teardown_defined_constants
       ActiveSupport::Dependencies.clear
     end
-
-    def teardown_defined_constants
-      ActiveSupport::Dependencies.clear
-    end
   end
 end

spec/support/unit/helpers/model_builder.rb

@@ -8,6 +8,7 @@ module UnitTests
       example_group.include(self)
 
       example_group.after do
+        clear_column_caches
         drop_created_tables
       end
     end
@@ -76,6 +77,18 @@ module UnitTests
 
     private
 
+    def clear_column_caches
+      # Rails 3.1 - 4.0
+      if ActiveRecord::Base.connection_pool.respond_to?(:clear_cache!)
+        ActiveRecord::Base.connection_pool.clear_cache!
+      end
+
+      # Rails 4.x
+      if ActiveRecord::Base.connection.respond_to?(:schema_cache)
+        ActiveRecord::Base.connection.schema_cache.clear!
+      end
+    end
+
     def drop_created_tables
       connection = ActiveRecord::Base.connection