`add_foreign_key`'s arguments are compatible (invertable) for...

`add_foreign_key`'s arguments are compatible (invertable) for `remove_foreign_key` without customize

So the custom `invert_add_foreign_key` is a little redundant.

activerecord/lib/active_record/migration/command_recorder.rb

@@ -127,6 +127,7 @@ module StraightReversions # :nodoc:
               add_column:        :remove_column,
               add_timestamps:    :remove_timestamps,
               add_reference:     :remove_reference,
+              add_foreign_key:   :remove_foreign_key,
               enable_extension:  :disable_extension
             }.each do |cmd, inv|
               [[inv, cmd], [cmd, inv]].uniq.each do |method, inverse|
@@ -217,21 +218,6 @@ def invert_change_column_null(args)
           [:change_column_null, args]
         end
 
-        def invert_add_foreign_key(args)
-          from_table, to_table, add_options = args
-          add_options ||= {}
-
-          if add_options[:name]
-            options = { name: add_options[:name] }
-          elsif add_options[:column]
-            options = { column: add_options[:column] }
-          else
-            options = to_table
-          end
-
-          [:remove_foreign_key, [from_table, options]]
-        end
-
         def invert_remove_foreign_key(args)
           options = args.extract_options!
           from_table, to_table = args

activerecord/test/cases/migration/command_recorder_test.rb

@@ -337,7 +337,7 @@ def test_invert_disable_extension
 
       def test_invert_add_foreign_key
         enable = @recorder.inverse_of :add_foreign_key, [:dogs, :people]
-        assert_equal [:remove_foreign_key, [:dogs, :people]], enable
+        assert_equal [:remove_foreign_key, [:dogs, :people], nil], enable
       end
 
       def test_invert_remove_foreign_key
@@ -347,7 +347,7 @@ def test_invert_remove_foreign_key
 
       def test_invert_add_foreign_key_with_column
         enable = @recorder.inverse_of :add_foreign_key, [:dogs, :people, column: "owner_id"]
-        assert_equal [:remove_foreign_key, [:dogs, column: "owner_id"]], enable
+        assert_equal [:remove_foreign_key, [:dogs, :people, column: "owner_id"], nil], enable
       end
 
       def test_invert_remove_foreign_key_with_column
@@ -357,7 +357,7 @@ def test_invert_remove_foreign_key_with_column
 
       def test_invert_add_foreign_key_with_column_and_name
         enable = @recorder.inverse_of :add_foreign_key, [:dogs, :people, column: "owner_id", name: "fk"]
-        assert_equal [:remove_foreign_key, [:dogs, name: "fk"]], enable
+        assert_equal [:remove_foreign_key, [:dogs, :people, column: "owner_id", name: "fk"], nil], enable
       end
 
       def test_invert_remove_foreign_key_with_column_and_name