Make the .message field on exceptions non-empty

[ekzhang]

This allows subclasses of SanicException to access their message via the message attribute. This makes it consistent with the status_code, quiet, headers attributes that were previously present on the class.

Currently, the message attribute is present on the class but not on the instance, so accessing SanicException("Failed!").message will return an empty string "" instead of the actual message "Failed!", which you can get by calling the __str__() method or str() function.

This is a bit surprising, since the .message attribute shows up in autocomplete and type-checking. It also happens for the other exceptions, like BadRequest().message == "" as well.

I set the message attribute on instances of SanicException and added tests for this new behavior.

Doc reference

https://sanic.dev/en/guide/best-practices/exceptions.html#exception-properties

[ekzhang]

Hi @Tronic, I updated the constructor to decode bytes arguments to str. It is a bit more verbose but works without disabling the type-checker on that line now.

I also updated the test!

---

The current CI failures appear to be from an unrelated error to this changeset.

sanic/request/types.py:89: error: "ctx_type" cannot appear after "sanic_type" in type parameter list because it has no default type  [misc]

[Tronic]

LGTM, if not barring minor cleanup (e.g. removal of "utf8" argument on decode, perhaps some restructuring). I will assume @ahopkins to do another review before merging; from my point this is approved as is or with changes. Thanks for the contribution!

[ekzhang]

if not barring minor cleanup (e.g. removal of "utf8" argument on decode, perhaps some restructuring).

Thanks for reviewing so quickly! I followed the pattern of the existing code to use .decode("utf8") but I'm also happy to amend that call or restructure anything.

[ahopkins]

@ekzhang I made some changes to the PR to keep the logic closer to the original intent to handle some of the border cases that your implementation may have broken. Thanks for the PR, and I certainly appreciate the additional tests you added.

[ekzhang]

That's amazing, thank you!!