Derive PartialEq for Json extractor

[jkylling]

Motivation

It should be possible to test handlers using

assert_eq!((StatusCode::OK, Json(MyStruct)), my_handler().await);

Currently, this can only be achieved with

let (status_code, Json(response)) = my_handler().await;
assert_eq!(StatusCode::OK, status_code);
assert_eq!(MyStruct, response);

Solution

[jplatte]

If we do this, we should do it for all the extractors that just consist of a single generic field, including those in axum-extra.

I think your second test code snippet is actually better though, since it will print a simpler / more specific error message if the assert fails.
Is this sort of test code your only motivation for wanting to add this trait impl?