Merge pull request #18272 from kamipo/fix_warning_assigned_but_unused_variable

Fix warning: assigned but unused variable - post

activerecord/test/cases/associations/has_one_associations_test.rb

@@ -577,7 +577,7 @@ def test_has_one_autosave_with_primary_key_manually_set
   def test_has_one_loading_for_new_record
     post = Post.create!(author_id: 42, title: 'foo', body: 'bar')
     author = Author.new(id: 42)
-    assert author.post
+    assert_equal post, author.post
   end
 
   def test_has_one_relationship_cannot_have_a_counter_cache