Fix #6628 - JSONDecodeError are not deserializable

src/requests/exceptions.py

@@ -41,6 +41,16 @@ def __init__(self, *args, **kwargs):
         CompatJSONDecodeError.__init__(self, *args)
         InvalidJSONError.__init__(self, *self.args, **kwargs)
 
+    def __reduce__(self):
+        """
+        The __reduce__ method called when pickling the object must
+        be the one from the JSONDecodeError (be it json/simplejson)
+        as it expects all the arguments for instantiation, not just
+        one like the IOError, and the MRO would by default call the
+        __reduce__ method from the IOError due to the inheritance order.
+        """
+        return CompatJSONDecodeError.__reduce__(self)
+
 
 class HTTPError(RequestException):
     """An HTTP error occurred."""

tests/test_requests.py

@@ -2810,3 +2810,13 @@ def test_status_code_425(self):
         assert r4 == 425
         assert r5 == 425
         assert r6 == 425
+
+
+def test_json_decode_errors_are_serializable_deserializable():
+    json_decode_error = requests.exceptions.JSONDecodeError(
+        "Extra data",
+        '{"responseCode":["706"],"data":null}{"responseCode":["706"],"data":null}',
+        36,
+    )
+    deserialized_error = pickle.loads(pickle.dumps(json_decode_error))
+    assert repr(json_decode_error) == repr(deserialized_error)