Merge pull request #33027 from bkuhlmann/reverse_sql_order_patch-51

Fixed `reverse_order` Arel SQL literal issue.

actioncable/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Back port Rails 5.2 `reverse_order` Arel SQL literal fix.
+
+    *Matt Jones*, *Brooke Kuhlmann*
+
 ## Rails 5.1.6 (March 29, 2018) ##
 
 *   No changes.

activerecord/lib/active_record/relation/query_methods.rb

@@ -1079,7 +1079,7 @@ def reverse_sql_order(order_query)
             end
             o.split(",").map! do |s|
               s.strip!
-              s.gsub!(/\sasc\Z/i, " DESC") || s.gsub!(/\sdesc\Z/i, " ASC") || s.concat(" DESC")
+              s.gsub!(/\sasc\Z/i, " DESC") || s.gsub!(/\sdesc\Z/i, " ASC") || (s << " DESC")
             end
           else
             o

activerecord/test/cases/relations_test.rb

@@ -253,6 +253,20 @@ def test_reverse_order_with_function_other_predicates
     assert_equal topics(:fifth).title, topics.first.title
   end
 
+  def test_reverse_order_with_string
+    result = Topic.order("id").reverse_order
+    proof = [5, 4, 3, 2, 1]
+
+    assert_equal result.pluck(:id), proof
+  end
+
+  def test_reverse_order_with_arel_literal
+    result = Topic.order(Arel::Nodes::SqlLiteral.new("id")).reverse_order
+    proof = [5, 4, 3, 2, 1]
+
+    assert_equal result.pluck(:id), proof
+  end
+
   def test_reverse_order_with_multiargument_function
     assert_raises(ActiveRecord::IrreversibleOrderError) do
       Topic.order("concat(author_name, title)").reverse_order