Down integrate from Google internal.

1 files changed, 20 insertions, 0 deletions

diff --git a/python/google/protobuf/internal/unknown_fields_test.py b/python/google/protobuf/internal/unknown_fields_test.py
index bb2748e4..84073f1c 100755
--- a/python/google/protobuf/internal/unknown_fields_test.py
+++ b/python/google/protobuf/internal/unknown_fields_test.py
@@ -119,6 +119,26 @@ class UnknownFieldsTest(unittest.TestCase):
     message.ParseFromString(self.all_fields.SerializeToString())
     self.assertNotEqual(self.empty_message, message)
 
+  def testDiscardUnknownFields(self):
+    self.empty_message.DiscardUnknownFields()
+    self.assertEqual(b'', self.empty_message.SerializeToString())
+    # Test message field and repeated message field.
+    message = unittest_pb2.TestAllTypes()
+    other_message = unittest_pb2.TestAllTypes()
+    other_message.optional_string = 'discard'
+    message.optional_nested_message.ParseFromString(
+        other_message.SerializeToString())
+    message.repeated_nested_message.add().ParseFromString(
+        other_message.SerializeToString())
+    self.assertNotEqual(
+        b'', message.optional_nested_message.SerializeToString())
+    self.assertNotEqual(
+        b'', message.repeated_nested_message[0].SerializeToString())
+    message.DiscardUnknownFields()
+    self.assertEqual(b'', message.optional_nested_message.SerializeToString())
+    self.assertEqual(
+        b'', message.repeated_nested_message[0].SerializeToString())
+
 
 class UnknownFieldsAccessorsTest(unittest.TestCase):