Reset default scope in Thread.current when class is unloaded [#5497 s…

…tate:resolved]

Signed-off-by: Xavier Noria <fxn@hashref.com>

activerecord/lib/active_record/base.rb

@@ -890,6 +890,10 @@ def scoped_methods #:nodoc:
         Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
       end
 
+      def before_remove_const #:nodoc:
+        reset_scoped_methods
+      end
+
       private
 
         def relation #:nodoc:
@@ -1174,6 +1178,10 @@ def current_scoped_methods #:nodoc:
           scoped_methods.last
         end
 
+        def reset_scoped_methods #:nodoc:
+          Thread.current[:"#{self}_scoped_methods"] = nil
+        end
+
         # Returns the class type of the record using the current module as a prefix. So descendants of
         # MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
         def compute_type(type_name)

activerecord/test/cases/base_test.rb

@@ -1415,6 +1415,21 @@ def test_compute_type_no_method_error
     end
   end
 
+  def test_default_scope_is_reset
+    Object.const_set :UnloadablePost, Class.new(ActiveRecord::Base)
+    UnloadablePost.table_name = 'posts'
+    UnloadablePost.class_eval do
+      default_scope order('posts.comments_count ASC')
+    end
+
+    UnloadablePost.unloadable
+    assert_not_nil Thread.current[:UnloadablePost_scoped_methods]
+    ActiveSupport::Dependencies.remove_unloadable_constants!
+    assert_nil Thread.current[:UnloadablePost_scoped_methods]
+  ensure
+    Object.class_eval{ remove_const :UnloadablePost } if defined?(UnloadablePost)
+  end
+
   protected
     def with_env_tz(new_tz = 'US/Eastern')
       old_tz, ENV['TZ'] = ENV['TZ'], new_tz