add feature (#704) Check if args/kwargs are JSON Serializable while r…

…unning locally (#1154)

* ✨ add feature (#705)
- JSON unserializable content passed to asyncronous task during local develop will raise exception on purpose to allow developers to catch JSON unserializable errors during development.

:white_check_mark: add `test_async_call_arg_not_json_seralizable` testcase
:fire: remove unnecessary coding comment in `test_async.py`

* :art: fix flake8

* :pencil: fix typo
:wrench: add specific `UnserializableJsonError` exception for clarity

* :white_check_mark: expand testcase to include custome exception, `UnserializableJsonError`.

* :art: run isort/black

* :fire: remove unnecessary assert

Co-authored-by: javulticat <[email protected]>

* :recycle: simplify `validate_json_serializable()` to accept *args, **kwargs as per review comment

* :fire: remove unnecessary import and use `object()` as unserializable_object sample.

Co-authored-by: javulticat <[email protected]>

tests/tests_async.py

@@ -1,4 +1,3 @@
-# -*- coding: utf8 -*-
 import os
 import unittest
 
@@ -17,6 +16,7 @@
     get_func_task_path,
     import_and_get_task,
 )
+from zappa.utilities import UnserializableJsonError
 
 
 class TestZappa(unittest.TestCase):
@@ -94,3 +94,10 @@ def test_async_call_with_defaults(self):
             lambda_function_name="MyLambda",
         )
         lambda_async_mock.return_value.send.assert_called_with(get_func_task_path(async_me), ("qux",), {})
+
+    def test_async_call_arg_not_json_serializable(self):
+        """Exception is raised when calling an async function locally (not on aws)"""
+        async_me = import_and_get_task("tests.test_app.async_me")
+        unserializable_object = object()
+        with self.assertRaises(UnserializableJsonError):
+            async_me(unserializable_object)

zappa/asynchronous.py

@@ -96,7 +96,7 @@ def my_async_func(*args, **kwargs):
 import boto3
 import botocore
 
-from .utilities import get_topic_name
+from .utilities import get_topic_name, validate_json_serializable
 
 try:
     from zappa_settings import ASYNC_RESPONSE_TABLE
@@ -430,6 +430,7 @@ def _run_async(*args, **kwargs):
                 ).send(task_path, args, kwargs)
                 return send_result
             else:
+                validate_json_serializable(*args, **kwargs)
                 return func(*args, **kwargs)
 
         update_wrapper(_run_async, func)

zappa/utilities.py

@@ -9,13 +9,21 @@
 import shutil
 import stat
 import sys
+from typing import Any
 from urllib.parse import urlparse
 
 import botocore
 import durationpy
 
 LOG = logging.getLogger(__name__)
 
+
+class UnserializableJsonError(TypeError):
+    """Exception class for JSON encoding errors"""
+
+    pass
+
+
 ##
 # Settings / Packaging
 ##
@@ -592,3 +600,10 @@ def merge_headers(event):
     for h in multi_headers.keys():
         multi_headers[h] = ", ".join(multi_headers[h])
     return multi_headers
+
+
+def validate_json_serializable(*args: Any, **kwargs: Any) -> None:
+    try:
+        json.dumps((args, kwargs))
+    except (TypeError, OverflowError):
+        raise UnserializableJsonError("Arguments to an asynchronous.task must be JSON serializable!")