2 files changed, 38 insertions, 7 deletions
diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index d77d76cb1e..fe94662543 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -457,10 +457,16 @@ module ActiveRecord
       # If the record is new or it has changed, returns true.
       def record_changed?(reflection, record, key)
         record.new_record? ||
-          (record.has_attribute?(reflection.foreign_key) && record[reflection.foreign_key] != key) ||
+          association_foreign_key_changed?(reflection, record, key) ||
           record.will_save_change_to_attribute?(reflection.foreign_key)
       end
 
+      def association_foreign_key_changed?(reflection, record, key)
+        return false if reflection.through_reflection?
+
+        record.has_attribute?(reflection.foreign_key) && record[reflection.foreign_key] != key
+      end
+
       # Saves the associated record if it's new or <tt>:autosave</tt> is enabled.
       #
       # In addition, it will destroy the association if it was marked for destruction.
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 54eb885f6a..1a0732c14b 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "cases/helper"
+require "models/author"
 require "models/bird"
 require "models/post"
 require "models/comment"
@@ -1319,21 +1320,45 @@ end
 class TestAutosaveAssociationOnAHasOneThroughAssociation < ActiveRecord::TestCase
   self.use_transactional_tests = false unless supports_savepoints?
 
-  def setup
-    super
+  def create_member_with_organization
     organization = Organization.create
-    @member = Member.create
-    MemberDetail.create(organization: organization, member: @member)
+    member = Member.create
+    MemberDetail.create(organization: organization, member: member)
+
+    member
   end
 
   def test_should_not_has_one_through_model
-    class << @member.organization
+    member = create_member_with_organization
+
+    class << member.organization
+      def save(*args)
+        super
+        raise "Oh noes!"
+      end
+    end
+    assert_nothing_raised { member.save }
+  end
+
+  def create_author_with_post_with_comment
+    Author.create! name: "David" # make comment_id not match author_id
+    author = Author.create! name: "Sergiy"
+    post = Post.create! author: author, title: "foo", body: "bar"
+    Comment.create! post: post, body: "cool comment"
+
+    author
+  end
+
+  def test_should_not_reversed_has_one_through_model
+    author = create_author_with_post_with_comment
+
+    class << author.comment_on_first_post
       def save(*args)
         super
         raise "Oh noes!"
       end
     end
-    assert_nothing_raised { @member.save }
+    assert_nothing_raised { author.save }
   end
 end