1 files changed, 45 insertions, 0 deletions
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index 019406dd84..de7acdf3ab 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -176,6 +176,51 @@ module ActiveRecord
         assert_nil @connection.pk_and_sequence_for('unobtainium')
       end
 
+      def test_pk_and_sequence_for_with_collision_pg_class_oid
+        @connection.exec_query('create table ex(id serial primary key)')
+        @connection.exec_query('create table ex2(id serial primary key)')
+
+        correct_depend_record = [
+          "'pg_class'::regclass",
+          "'ex_id_seq'::regclass",
+          '0',
+          "'pg_class'::regclass",
+          "'ex'::regclass",
+          '1',
+          "'a'"
+        ]
+
+        collision_depend_record = [
+          "'pg_attrdef'::regclass",
+          "'ex2_id_seq'::regclass",
+          '0',
+          "'pg_class'::regclass",
+          "'ex'::regclass",
+          '1',
+          "'a'"
+        ]
+
+        @connection.exec_query(
+          "DELETE FROM pg_depend WHERE objid = 'ex_id_seq'::regclass AND refobjid = 'ex'::regclass AND deptype = 'a'"
+        )
+        @connection.exec_query(
+          "INSERT INTO pg_depend VALUES(#{collision_depend_record.join(',')})"
+        )
+        @connection.exec_query(
+          "INSERT INTO pg_depend VALUES(#{correct_depend_record.join(',')})"
+        )
+
+        seq = @connection.pk_and_sequence_for('ex').last
+        assert_equal 'ex_id_seq', seq
+
+        @connection.exec_query(
+          "DELETE FROM pg_depend WHERE objid = 'ex2_id_seq'::regclass AND refobjid = 'ex'::regclass AND deptype = 'a'"
+        )
+      ensure
+        @connection.exec_query('DROP TABLE IF EXISTS ex')
+        @connection.exec_query('DROP TABLE IF EXISTS ex2')
+      end
+
       def test_exec_insert_number
         with_example_table do
           insert(@connection, 'number' => 10)