1 files changed, 16 insertions, 1 deletions
diff --git a/activerecord/test/cases/sanitize_test.rb b/activerecord/test/cases/sanitize_test.rb
index 082570c55b..766b2ff2ef 100644
--- a/activerecord/test/cases/sanitize_test.rb
+++ b/activerecord/test/cases/sanitize_test.rb
@@ -1,5 +1,7 @@
 require "cases/helper"
 require 'models/binary'
+require 'models/author'
+require 'models/post'
 
 class SanitizeTest < ActiveRecord::TestCase
   def setup
@@ -9,7 +11,7 @@ class SanitizeTest < ActiveRecord::TestCase
     quoted_bambi = ActiveRecord::Base.connection.quote("Bambi")
     quoted_column_name = ActiveRecord::Base.connection.quote_column_name("name")
     quoted_table_name = ActiveRecord::Base.connection.quote_table_name("adorable_animals")
-    expected_value = "#{quoted_table_name}.#{quoted_column_name} = #{quoted_bambi}" 
+    expected_value = "#{quoted_table_name}.#{quoted_column_name} = #{quoted_bambi}"
 
     assert_equal expected_value, Binary.send(:sanitize_sql_hash, {adorable_animals: {name: 'Bambi'}})
   end
@@ -31,4 +33,17 @@ 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
+    david = Author.create!(name: 'David')
+    david_posts = david.posts.select(:id)
+
+    sub_query_pattern = /\(\bselect\b.*?\bwhere\b.*?\)/i
+
+    select_author_sql = Post.send(:sanitize_sql_array, ['id in (?)', david_posts])
+    assert_match(sub_query_pattern, select_author_sql, 'should sanitize `Relation` as subquery for bind variables')
+
+    select_author_sql = Post.send(:sanitize_sql_array, ['id in (:post_ids)', post_ids: david_posts])
+    assert_match(sub_query_pattern, select_author_sql, 'should sanitize `Relation` as subquery for named bind variables')
+  end
 end