From 056b62a237252057d48b20b3d8d188fc6bdcb5ff Mon Sep 17 00:00:00 2001
From: Tomer Vromen <tomerv@gmail.com>
Date: Thu, 19 May 2022 14:08:50 +0300
Subject: [PATCH] Raise KeyError in Python ServiceDescriptor.FindMethodByName
 (#9592)

* Align Python version with C-extension version
  (python/google/protobuf/pyext/descriptor.cc)
* Update documentation accordingly
* Add unit test
---
 python/google/protobuf/descriptor.py               | 9 ++++++---
 python/google/protobuf/internal/descriptor_test.py | 8 ++++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/python/google/protobuf/descriptor.py b/python/google/protobuf/descriptor.py
index f5a0caa6bd..fa7a5b96d5 100644
--- a/python/google/protobuf/descriptor.py
+++ b/python/google/protobuf/descriptor.py
@@ -873,11 +873,14 @@ class ServiceDescriptor(_NestedDescriptorBase):
 
     Args:
       name (str): Name of the method.
+
     Returns:
-      MethodDescriptor or None: the descriptor for the requested method, if
-      found.
+      MethodDescriptor: The descriptor for the requested method.
+
+    Raises:
+      KeyError: if the method cannot be found in the service.
     """
-    return self.methods_by_name.get(name, None)
+    return self.methods_by_name[name]
 
   def CopyToProto(self, proto):
     """Copies this to a descriptor_pb2.ServiceDescriptorProto.
diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index 6a8532c408..8c43e476f9 100644
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -118,6 +118,14 @@ class DescriptorTest(unittest.TestCase):
   def GetDescriptorPool(self):
     return symbol_database.Default().pool
 
+  def testFindMethodByName(self):
+    service_descriptor = (unittest_custom_options_pb2.
+                          TestServiceWithCustomOptions.DESCRIPTOR)
+    method_descriptor = service_descriptor.FindMethodByName('Foo')
+    self.assertEqual(method_descriptor.name, 'Foo')
+    with self.assertRaises(KeyError):
+        service_descriptor.FindMethodByName('MethodDoesNotExist')
+
   def testEnumValueName(self):
     self.assertEqual(self.my_message.EnumValueName('ForeignEnum', 4),
                      'FOREIGN_FOO')