def METHOD_NAME(self):
    serialized_desc = b'\n\ntest.proto\"\x0e\n\x02M1*\x08\x08\x01\x10\x80\x80\x80\x80\x02:\x15\n\x08test_ext\x12\x03.M1\x18\x01 \x01(\x05'
    pool = _message.DescriptorPool()
    file_desc = pool.AddSerializedFile(serialized_desc)
    self.assertEqual("test.proto", file_desc.name)
    ext_desc = pool.FindExtensionByName("test_ext")
    self.assertEqual(1, ext_desc.number)
    # Test object cache: repeatedly retrieving the same descriptor
    # should result in the same object
    self.assertIs(ext_desc, pool.FindExtensionByName("test_ext"))