From 2870d2fe1defee6908da96fdb331044cc9427ce6 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Tue, 19 Apr 2022 13:22:22 +0200
Subject: [PATCH 01/13] empty commit


From d7611bd01d0149bfef555d29e3a98b2fa5dcde70 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Tue, 19 Apr 2022 13:25:25 +0200
Subject: [PATCH 02/13] Revert "Revert "Use python3.9 which is available on
 brew to run tests""

This reverts commit bd28ee1c5ce04e25584e072e5e3e36990c2e2cb8.
---
 tests.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests.sh b/tests.sh
index 71635f9f7f4d8..bce56b4e39c66 100755
--- a/tests.sh
+++ b/tests.sh
@@ -326,7 +326,7 @@ build_python() {
   if [ $(uname -s) == "Linux" ]; then
     envlist=py\{35,36\}-python
   else
-    envlist=py\{36\}-python
+    envlist=py\{39\}-python
   fi
   python -m tox -e $envlist
   cd ..
@@ -376,7 +376,7 @@ build_python_cpp() {
   if [ $(uname -s) == "Linux" ]; then
     envlist=py\{35,36\}-cpp
   else
-    envlist=py\{36\}-cpp
+    envlist=py\{39\}-cpp
   fi
   tox -e $envlist
   cd ..

From e36ea59917ad0bfb499f3066ef477c1899259bd8 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Tue, 19 Apr 2022 14:47:01 +0200
Subject: [PATCH 03/13] make it standalone

---
 python/google/protobuf/json_format.py | 39 ++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index b3e85933e9609..a391f204473b6 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -43,6 +43,7 @@
 __author__ = 'jieluo@google.com (Jie Luo)'
 
 
+import ctypes
 import base64
 from collections import OrderedDict
 import json
@@ -51,7 +52,6 @@
 import re
 import sys
 
-from google.protobuf.internal import type_checkers
 from google.protobuf import descriptor
 from google.protobuf import symbol_database
 
@@ -75,6 +75,37 @@
 _VALID_EXTENSION_NAME = re.compile(r'\[[a-zA-Z0-9\._]*\]$')
 
 
+# NOTE(anton): copied from internal/type_checkers.py to avoid having json_format.py depend on internal interface of the
+# protobuf
+# library.
+# Depending on an internal protobuf interface can hurt us since we are forking this file in noom-contracts, and the
+# version of the protobuf libary used on the client is under client's control.
+# The other two imports in this file (descriptor and symbol_database) are part of the protobuf public interface, and
+# there is less risk that this will change under us.
+def TruncateToFourByteFloat(original):
+  return ctypes.c_float(original).value
+
+
+# NOTE(anton): same comment from above TruncateToFourByteFloat applies here.
+def ToShortestFloat(original):
+  """Returns the shortest float that has same value in wire."""
+  # All 4 byte floats have between 6 and 9 significant digits, so we
+  # start with 6 as the lower bound.
+  # It has to be iterative because use '.9g' directly can not get rid
+  # of the noises for most values. For example if set a float_field=0.9
+  # use '.9g' will print 0.899999976.
+  precision = 6
+  rounded = float('{0:.{1}g}'.format(original, precision))
+  while TruncateToFourByteFloat(rounded) != original:
+    precision += 1
+    rounded = float('{0:.{1}g}'.format(original, precision))
+  return rounded
+
+# NOTE(anton): same comment from above TruncateToFourByteFloat applies here.
+_FLOAT_MAX = float.fromhex('0x1.fffffep+127')
+_FLOAT_MIN = -_FLOAT_MAX
+
+
 class Error(Exception):
   """Top-level module error for json_format."""
 
@@ -308,7 +339,7 @@ def _FieldToJsonObject(self, field, value):
         if self.float_format:
           return float(format(value, self.float_format))
         else:
-          return type_checkers.ToShortestFloat(value)
+          return ToShortestFloat(value)
 
     return value
 
@@ -791,10 +822,10 @@ def _ConvertFloat(value, field):
                          'use quoted "-Infinity" instead.')
     if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_FLOAT:
       # pylint: disable=protected-access
-      if value > type_checkers._FLOAT_MAX:
+      if value > _FLOAT_MAX:
         raise ParseError('Float value too large')
       # pylint: disable=protected-access
-      if value < type_checkers._FLOAT_MIN:
+      if value < _FLOAT_MIN:
         raise ParseError('Float value too small')
   if value == 'nan':
     raise ParseError('Couldn\'t parse float "nan", use "NaN" instead.')

From 3878da28f18a950c90b55b72d480308452fe16d9 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Tue, 19 Apr 2022 14:49:41 +0200
Subject: [PATCH 04/13] fix code spell

---
 python/google/protobuf/json_format.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index a391f204473b6..9f569f50b7964 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -79,7 +79,7 @@
 # protobuf
 # library.
 # Depending on an internal protobuf interface can hurt us since we are forking this file in noom-contracts, and the
-# version of the protobuf libary used on the client is under client's control.
+# version of the protobuf library used on the client is under client's control.
 # The other two imports in this file (descriptor and symbol_database) are part of the protobuf public interface, and
 # there is less risk that this will change under us.
 def TruncateToFourByteFloat(original):

From cc973ed4f30b97b7019e1937ac1ad8b1c0cd81e3 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Fri, 22 Apr 2022 16:53:55 +0200
Subject: [PATCH 05/13] implement ignoring unknown enum values

---
 .../protobuf/internal/json_format_test.py     | 17 ++++++
 python/google/protobuf/json_format.py         | 57 +++++++++++++++----
 2 files changed, 63 insertions(+), 11 deletions(-)

diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
index 6a44d4c97db0a..4125a5530a046 100755
--- a/python/google/protobuf/internal/json_format_test.py
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -909,6 +909,23 @@ def testParseEnumValue(self):
         'for enum type protobuf_unittest.TestAllTypes.NestedEnum.',
         json_format.Parse, '{"optionalNestedEnum": 12345}', message)
 
+  def testParseUnknownEnumStringValueProto3(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = '{"enumValue": "UNKNOWN_STRING_VALUE"}'
+    json_format.Parse(text, message, ignore_unknown_fields=True)
+
+  def testParseUnknownEnumStringValueRepeatedProto3(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = '{"repeatedEnumValue": ["UNKNOWN_STRING_VALUE", "FOO", "BAR"]}'
+    json_format.Parse(text, message, ignore_unknown_fields=True)
+    self.assertEquals(len(message.repeated_enum_value), 2)
+
+  def testParseUnknownEnumStringValueProto2(self):
+    message = json_format_pb2.TestNumbers()
+    text = '{"a": "UNKNOWN_STRING_VALUE"}'
+    json_format.Parse(text, message, ignore_unknown_fields=True)
+    self.assertFalse(message.HasField("a"))
+
   def testBytes(self):
     message = json_format_proto3_pb2.TestMessage()
     # Test url base64
diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index b3e85933e9609..2533b6800fcca 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -87,6 +87,33 @@ class ParseError(Error):
   """Thrown in case of parsing error."""
 
 
+class _UnknownEnumStringValueParseError(ParseError):
+  """Thrown if an unknown enum string value is encountered. This exception never leaks outside of the module."""
+
+
+class _MaybeSuppressUnknownEnumStringValueParseError():
+  """
+  Example usage:
+
+  with _MaybeSuppressUnknownEnumStringValueParseError(True):
+    ...
+
+  If should_suppress is True, the _UnknownEnumStringValueParseError will be ignored in the context body.
+  """
+  def __init__(self, should_suppress):
+    self.should_suppress = should_suppress
+
+  def __enter__(self):
+    pass
+
+  def __exit__(self, exc_type, exc_value, traceback):
+    # The return value from __exit__ indicates if any exception that occurred in the context body should be suppressed.
+    # We suppress _UnknownEnumStringValueParseError if should_suppress is set.
+    # See context manager docs:
+    # https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers
+    return self.should_suppress and exc_type == _UnknownEnumStringValueParseError
+
+
 def MessageToJson(
     message,
     including_default_value_fields=False,
@@ -569,8 +596,9 @@ def _ConvertFieldValuePair(self, js, message):
               if item is None:
                 raise ParseError('null is not allowed to be used as an element'
                                  ' in a repeated field.')
-              getattr(message, field.name).append(
-                  _ConvertScalarFieldValue(item, field))
+              with _MaybeSuppressUnknownEnumStringValueParseError(self.ignore_unknown_fields):
+                getattr(message, field.name).append(
+                    _ConvertScalarFieldValue(item, field))
         elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
           if field.is_extension:
             sub_message = message.Extensions[field]
@@ -579,10 +607,11 @@ def _ConvertFieldValuePair(self, js, message):
           sub_message.SetInParent()
           self.ConvertMessage(value, sub_message)
         else:
-          if field.is_extension:
-            message.Extensions[field] = _ConvertScalarFieldValue(value, field)
-          else:
-            setattr(message, field.name, _ConvertScalarFieldValue(value, field))
+          with _MaybeSuppressUnknownEnumStringValueParseError(self.ignore_unknown_fields):
+            if field.is_extension:
+              message.Extensions[field] = _ConvertScalarFieldValue(value, field)
+            else:
+              setattr(message, field.name, _ConvertScalarFieldValue(value, field))
       except ParseError as e:
         if field and field.containing_oneof is None:
           raise ParseError('Failed to parse {0} field: {1}.'.format(name, e))
@@ -669,7 +698,8 @@ def _ConvertStructMessage(self, value, message):
   def _ConvertWrapperMessage(self, value, message):
     """Convert a JSON representation into Wrapper message."""
     field = message.DESCRIPTOR.fields_by_name['value']
-    setattr(message, 'value', _ConvertScalarFieldValue(value, field))
+    with _MaybeSuppressUnknownEnumStringValueParseError(self.ignore_unknown_fields):
+      setattr(message, 'value', _ConvertScalarFieldValue(value, field))
 
   def _ConvertMapFieldValue(self, value, message, field):
     """Convert map field value for a message map field.
@@ -689,13 +719,15 @@ def _ConvertMapFieldValue(self, value, message, field):
     key_field = field.message_type.fields_by_name['key']
     value_field = field.message_type.fields_by_name['value']
     for key in value:
-      key_value = _ConvertScalarFieldValue(key, key_field, True)
+      with _MaybeSuppressUnknownEnumStringValueParseError(self.ignore_unknown_fields):
+        key_value = _ConvertScalarFieldValue(key, key_field, True)
       if value_field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
         self.ConvertMessage(value[key], getattr(
             message, field.name)[key_value])
       else:
-        getattr(message, field.name)[key_value] = _ConvertScalarFieldValue(
-            value[key], value_field)
+        with _MaybeSuppressUnknownEnumStringValueParseError(self.ignore_unknown_fields):
+          getattr(message, field.name)[key_value] = _ConvertScalarFieldValue(
+              value[key], value_field)
 
 
 def _ConvertScalarFieldValue(value, field, require_str=False):
@@ -711,6 +743,7 @@ def _ConvertScalarFieldValue(value, field, require_str=False):
 
   Raises:
     ParseError: In case of convert problems.
+    _UnknownEnumStringValueParseError: If unknown enum string value is encountered during parsing.
   """
   if field.cpp_type in _INT_TYPES:
     return _ConvertInteger(value)
@@ -741,7 +774,9 @@ def _ConvertScalarFieldValue(value, field, require_str=False):
         number = int(value)
         enum_value = field.enum_type.values_by_number.get(number, None)
       except ValueError:
-        raise ParseError('Invalid enum value {0} for enum type {1}.'.format(
+        # The ValueError will be raised by the conversion to int.
+        # That means that here we know that we have an unknown enum string value.
+        raise _UnknownEnumStringValueParseError('Invalid enum value {0} for enum type {1}.'.format(
             value, field.enum_type.full_name))
       if enum_value is None:
         if field.file.syntax == 'proto3':

From e72f8a99c1aa1221921cdff99636ad304f1de583 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Fri, 22 Apr 2022 16:58:21 +0200
Subject: [PATCH 06/13] self review

---
 .../google/protobuf/internal/json_format_test.py  | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
index 4125a5530a046..aa56692e8e165 100755
--- a/python/google/protobuf/internal/json_format_test.py
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -913,19 +913,22 @@ def testParseUnknownEnumStringValueProto3(self):
     message = json_format_proto3_pb2.TestMessage()
     text = '{"enumValue": "UNKNOWN_STRING_VALUE"}'
     json_format.Parse(text, message, ignore_unknown_fields=True)
-
-  def testParseUnknownEnumStringValueRepeatedProto3(self):
-    message = json_format_proto3_pb2.TestMessage()
-    text = '{"repeatedEnumValue": ["UNKNOWN_STRING_VALUE", "FOO", "BAR"]}'
-    json_format.Parse(text, message, ignore_unknown_fields=True)
-    self.assertEquals(len(message.repeated_enum_value), 2)
+    # In proto3, there is no difference between the default value and 0.
+    self.assertEqual(message.enum_value, 0)
 
   def testParseUnknownEnumStringValueProto2(self):
     message = json_format_pb2.TestNumbers()
     text = '{"a": "UNKNOWN_STRING_VALUE"}'
     json_format.Parse(text, message, ignore_unknown_fields=True)
+    # In proto2 we can see that the field was not set at all.
     self.assertFalse(message.HasField("a"))
 
+  def testParseUnknownEnumStringValueRepeatedProto3(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = '{"repeatedEnumValue": ["UNKNOWN_STRING_VALUE", "FOO", "BAR"]}'
+    json_format.Parse(text, message, ignore_unknown_fields=True)
+    self.assertEquals(len(message.repeated_enum_value), 2)
+
   def testBytes(self):
     message = json_format_proto3_pb2.TestMessage()
     # Test url base64

From b0f3ef2fa5a463d03f9592963cb2b0f8753d54b4 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Fri, 22 Apr 2022 17:13:33 +0200
Subject: [PATCH 07/13] self review

---
 python/google/protobuf/json_format.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index 35ea63e6de6c6..6781e0b88f202 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -130,6 +130,12 @@ class _MaybeSuppressUnknownEnumStringValueParseError():
     ...
 
   If should_suppress is True, the _UnknownEnumStringValueParseError will be ignored in the context body.
+
+  The motivation for the context manager is to avoid a bigger refactor that would enable _ConvertScalarFieldValue to
+  signal to the caller that the field should be ignored.
+
+  We want to avoid a bigger refactor because we are maintaining a fork and we want changes to be minimal to simplify
+  merging with upstream.
   """
   def __init__(self, should_suppress):
     self.should_suppress = should_suppress

From 66eb2d983c268e2dd152a7c48557ca5115baeea7 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Mon, 20 Jun 2022 17:17:32 +0200
Subject: [PATCH 08/13] address comments

---
 python/google/protobuf/json_format.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index 9f569f50b7964..573cc0d3dec52 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -76,8 +76,7 @@
 
 
 # NOTE(anton): copied from internal/type_checkers.py to avoid having json_format.py depend on internal interface of the
-# protobuf
-# library.
+# protobuf library.
 # Depending on an internal protobuf interface can hurt us since we are forking this file in noom-contracts, and the
 # version of the protobuf library used on the client is under client's control.
 # The other two imports in this file (descriptor and symbol_database) are part of the protobuf public interface, and
@@ -105,7 +104,6 @@ def ToShortestFloat(original):
 _FLOAT_MAX = float.fromhex('0x1.fffffep+127')
 _FLOAT_MIN = -_FLOAT_MAX
 
-
 class Error(Exception):
   """Top-level module error for json_format."""
 

From 0d8dabb911cac153f15082c50841037b4889ec17 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Mon, 20 Jun 2022 17:53:22 +0200
Subject: [PATCH 09/13] fix comment

---
 python/google/protobuf/json_format.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index fd78185c32567..3b164485bac0d 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -117,7 +117,7 @@ class ParseError(Error):
 
 
 class _UnknownEnumStringValueParseError(ParseError):
-  """Thrown if an unknown enum string value is encountered. This exception never leaks outside of the module."""
+  """Thrown if an unknown enum string value is encountered."""
 
 
 class _MaybeSuppressUnknownEnumStringValueParseError():

From f54c8b4d2055481f45e58c536baa8d7e60b4ce17 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Mon, 20 Jun 2022 18:07:27 +0200
Subject: [PATCH 10/13] apply advice from Clements

---
 python/google/protobuf/json_format.py | 38 ++++++++-------------------
 1 file changed, 11 insertions(+), 27 deletions(-)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index 3b164485bac0d..62068fa72ca46 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -51,6 +51,7 @@
 from operator import methodcaller
 import re
 import sys
+from contextlib import contextmanager
 
 from google.protobuf import descriptor
 from google.protobuf import symbol_database
@@ -120,33 +121,16 @@ class _UnknownEnumStringValueParseError(ParseError):
   """Thrown if an unknown enum string value is encountered."""
 
 
-class _MaybeSuppressUnknownEnumStringValueParseError():
-  """
-  Example usage:
-
-  with _MaybeSuppressUnknownEnumStringValueParseError(True):
-    ...
-
-  If should_suppress is True, the _UnknownEnumStringValueParseError will be ignored in the context body.
-
-  The motivation for the context manager is to avoid a bigger refactor that would enable _ConvertScalarFieldValue to
-  signal to the caller that the field should be ignored.
-
-  We want to avoid a bigger refactor because we are maintaining a fork and we want changes to be minimal to simplify
-  merging with upstream.
-  """
-  def __init__(self, should_suppress):
-    self.should_suppress = should_suppress
-
-  def __enter__(self):
-    pass
-
-  def __exit__(self, exc_type, exc_value, traceback):
-    # The return value from __exit__ indicates if any exception that occurred in the context body should be suppressed.
-    # We suppress _UnknownEnumStringValueParseError if should_suppress is set.
-    # See context manager docs:
-    # https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers
-    return self.should_suppress and exc_type == _UnknownEnumStringValueParseError
+@contextmanager
+def _MaybeSuppressUnknownEnumStringValueParseError(should_suppress: bool):
+    try:
+        yield
+    except _UnknownEnumStringValueParseError as ex:
+        if should_suppress:
+            # Here we suppress _UnknownEnumStringValueParseError.
+            pass
+        else:
+            raise
 
 
 def MessageToJson(

From b34fb41dd1f44fba509597e45670b052a0260356 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Mon, 20 Jun 2022 18:08:22 +0200
Subject: [PATCH 11/13] just noting the typo above, should be Clemens


From 793ad1285790cd4e8211c60d8e69c03e943b7191 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Mon, 20 Jun 2022 18:11:19 +0200
Subject: [PATCH 12/13] add comment

---
 python/google/protobuf/json_format.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index 62068fa72ca46..c1f622ae3b90a 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -123,6 +123,12 @@ class _UnknownEnumStringValueParseError(ParseError):
 
 @contextmanager
 def _MaybeSuppressUnknownEnumStringValueParseError(should_suppress: bool):
+    """
+    This context manager will suppress _UnknownEnumStringValueParseError if the should_suppress is set to true. Usage:
+
+    with _MaybeSuppressUnknownEnumStringValueParseError(True):
+        run_some_code_that_might_throw()
+    """
     try:
         yield
     except _UnknownEnumStringValueParseError as ex:

From e2bfadb685a32a24f19e9aca52f62851310fae66 Mon Sep 17 00:00:00 2001
From: Anton Grbin <anton@noom.com>
Date: Tue, 21 Jun 2022 15:57:58 +0200
Subject: [PATCH 13/13] address review comments

---
 .../protobuf/internal/json_format_test.py     | 29 ++++++++++++++-----
 python/google/protobuf/json_format.py         |  5 +++-
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
index aa56692e8e165..c8275e6457a8b 100755
--- a/python/google/protobuf/internal/json_format_test.py
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -909,20 +909,35 @@ def testParseEnumValue(self):
         'for enum type protobuf_unittest.TestAllTypes.NestedEnum.',
         json_format.Parse, '{"optionalNestedEnum": 12345}', message)
 
-  def testParseUnknownEnumStringValueProto3(self):
-    message = json_format_proto3_pb2.TestMessage()
-    text = '{"enumValue": "UNKNOWN_STRING_VALUE"}'
-    json_format.Parse(text, message, ignore_unknown_fields=True)
-    # In proto3, there is no difference between the default value and 0.
-    self.assertEqual(message.enum_value, 0)
-
   def testParseUnknownEnumStringValueProto2(self):
     message = json_format_pb2.TestNumbers()
+    # Note that in src/google/protobuf/util/json_format.proto::TestNumbers
+    # has a field 'optional MyType a = 1', which is different
+    # from the test below that are using
+    # src/google/protobuf/util/json_format_proto3.proto::TestMessage.
     text = '{"a": "UNKNOWN_STRING_VALUE"}'
     json_format.Parse(text, message, ignore_unknown_fields=True)
     # In proto2 we can see that the field was not set at all.
     self.assertFalse(message.HasField("a"))
 
+  def testParseErrorCorrectCatchForUnknownEnumValue(self):
+    message = json_format_pb2.TestNumbers()
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Invalid enum value',
+        json_format.Parse, '{"a": "UNKNOWN_STRING_VALUE"}', message)
+
+  def testParseUnknownEnumStringValueProto3(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = '{"enumValue": "UNKNOWN_STRING_VALUE"}'
+    json_format.Parse(text, message, ignore_unknown_fields=True)
+    # In proto3, there is no difference between the default value and 0.
+    self.assertEqual(message.enum_value, 0)
+
+  # Note that in noom-contracts we banned the repeated enum fields, so this test
+  # is not adding value for Noom's use of this library.
+  # Still, we are testing that the behavior here is consistent with what
+  # binary serialization would do.
   def testParseUnknownEnumStringValueRepeatedProto3(self):
     message = json_format_proto3_pb2.TestMessage()
     text = '{"repeatedEnumValue": ["UNKNOWN_STRING_VALUE", "FOO", "BAR"]}'
diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index c1f622ae3b90a..9c55d4e5488c7 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -118,7 +118,10 @@ class ParseError(Error):
 
 
 class _UnknownEnumStringValueParseError(ParseError):
-  """Thrown if an unknown enum string value is encountered."""
+  """
+  Thrown if an unknown enum string value is encountered.
+  We inherit ParseError to avoid breaking the code that might expect ParseError.
+  """
 
 
 @contextmanager