cleanup, assert on warning from postgres adapter

activerecord/test/cases/relation_test.rb

@@ -189,7 +189,7 @@ def test_respond_to_for_non_selected_element
       post = Post.select(:title).first
       assert_equal false, post.respond_to?(:body), "post should not respond_to?(:body) since invoking it raises exception"
 
-      post = Post.select("'title' as post_title").first
+      silence_warnings { post = Post.select("'title' as post_title").first }
       assert_equal false, post.respond_to?(:title), "post should not respond_to?(:body) since invoking it raises exception"
     end