diff --git a/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py b/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
index 5163ffe..69192a2 100644
--- a/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
+++ b/src/python/grpcio_tests/tests/reflection/_reflection_servicer_test.py
@@ -51,6 +51,7 @@
 _SERVICE_NAMES = ('Angstrom', 'Bohr', 'Curie', 'Dyson', 'Einstein', 'Feynman',
                   'Galilei')
 _EMPTY_EXTENSIONS_SYMBOL_NAME = 'grpc.testing.proto2.EmptyWithExtensions'
+_EMPTY_EXTENSIONS_NUMBERS = (124, 125, 126, 127, 128,)
 
 
 def _file_descriptor_to_proto(descriptor):
@@ -137,6 +138,27 @@
                 )),)
         self.assertSequenceEqual(expected_responses, responses)
 
+    def testExtensionNumbersOfType(self):
+        requests = (reflection_pb2.ServerReflectionRequest(
+            all_extension_numbers_of_type=_EMPTY_EXTENSIONS_SYMBOL_NAME
+        ), reflection_pb2.ServerReflectionRequest(
+            all_extension_numbers_of_type='i.donut.exist.co.uk.net.name.foo'),)
+        responses = tuple(self._stub.ServerReflectionInfo(iter(requests)))
+        expected_responses = (
+            reflection_pb2.ServerReflectionResponse(
+                valid_host='',
+                all_extension_numbers_response=reflection_pb2.
+                ExtensionNumberResponse(
+                    base_type_name=_EMPTY_EXTENSIONS_SYMBOL_NAME,
+                    extension_number=_EMPTY_EXTENSIONS_NUMBERS)),
+            reflection_pb2.ServerReflectionResponse(
+                valid_host='',
+                error_response=reflection_pb2.ErrorResponse(
+                    error_code=grpc.StatusCode.NOT_FOUND.value[0],
+                    error_message=grpc.StatusCode.NOT_FOUND.value[1].encode(),
+                )),)
+        self.assertSequenceEqual(expected_responses, responses)
+
     def testListServices(self):
         requests = (reflection_pb2.ServerReflectionRequest(
             list_services='',),)