2 files changed, 11 insertions, 0 deletions
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index f814947ab2..0cd8595ba6 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -626,6 +626,11 @@ class RelationTest < ActiveRecord::TestCase
       relation = Author.where(:id => Author.where(:id => david.id))
       assert_equal [david], relation.to_a
     }
+
+    assert_queries(1) {
+      relation = Author.where('id in (?)', Author.where(id: david).select(:id))
+      assert_equal [david], relation.to_a
+    }
   end
 
   def test_find_all_using_where_with_relation_and_alternate_primary_key
diff --git a/activerecord/test/cases/sanitize_test.rb b/activerecord/test/cases/sanitize_test.rb
index 082570c55b..4c0762deca 100644
--- a/activerecord/test/cases/sanitize_test.rb
+++ b/activerecord/test/cases/sanitize_test.rb
@@ -31,4 +31,10 @@ class SanitizeTest < ActiveRecord::TestCase
     assert_equal "name=#{quoted_bambi_and_thumper}", Binary.send(:sanitize_sql_array, ["name=?", "Bambi\nand\nThumper"])
     assert_equal "name=#{quoted_bambi_and_thumper}", Binary.send(:sanitize_sql_array, ["name=?", "Bambi\nand\nThumper".mb_chars])
   end
+
+  def test_sanitize_sql_array_handles_relations
+    assert_match(/\(\bselect\b.*?\bwhere\b.*?\)/i,
+      Binary.send(:sanitize_sql_array, ["id in (?)", Binary.where(id: 1)]),
+      "should sanitize `Relation` as subquery")
+  end
 end