Move migration test together with other join table tests

Author: carlosantoniodasilva

activerecord/test/cases/migration/create_join_table_test.rb

@@ -35,6 +35,12 @@ def test_create_join_table_with_strings
         assert_equal %w(artist_id music_id), connection.columns(:artists_musics).map(&:name).sort
       end
 
+      def test_create_join_table_with_symbol_and_string
+        connection.create_join_table :artists, 'musics'
+
+        assert_equal %w(artist_id music_id), connection.columns(:artists_musics).map(&:name).sort
+      end
+
       def test_create_join_table_with_the_proper_order
         connection.create_join_table :videos, :musics
 

activerecord/test/cases/migration_test.rb

@@ -755,11 +755,4 @@ def test_copying_migrations_to_empty_directory
   ensure
     clear
   end
-
-  def test_create_join_table_with_symbol_and_string
-    connection.create_join_table :artists, 'musics'
-
-    assert_equal %w(artist_id music_id), connection.columns(:artists_musics).map(&:name).sort
-  end
-
 end