Add test for fixed `counter_cache` double increment

When an `after_create` callback did `update_attributes` on a record with
multiple `belongs_to` associations with counter caches, even numbered
associations would have their counters double-incremented. Fixes to
`ActiveModel::Dirty` in 020abad fixed this.

This adds regression tests for this bug fixed incidentally in the other
commit, which also removed the need for the workaround using
@_after_create_counter_called.

1 files changed, 11 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index a7ac291f23..7270060639 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -1167,6 +1167,17 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     Column.create! record: record
     assert_equal 1, Column.count
   end
+
+  def test_multiple_counter_cache_with_after_create_update
+    post = posts(:welcome)
+    parent = comments(:greetings)
+
+    assert_difference "parent.reload.children_count", +1 do
+      assert_difference "post.reload.comments_count", +1 do
+        comment = CommentWithAfterCreateUpdate.create(body: "foo", post: post, parent: parent)
+      end
+    end
+  end
 end
 
 class BelongsToWithForeignKeyTest < ActiveRecord::TestCase