Remove deprecated `MockedRequest.body` and cleanup

Scope

Improves an existing behavior

Compatibility

• This is a breaking change

Feature description

Remove deprecated MockedRequest.body and cleanup after few releases with deprecation.

https://github.com/mswjs/msw/issues/1302#issuecomment-1173722395

[kettanaito]

There’s some serious dark magic with generics sometimes. I believe we’re using a similar pattern right now, where we have a res.json<T>() signature but it gets inferred from the generic you give to the handler rest.get<T>(). I think we should keep JSON method annotated while hard-coding text and arrayBuffer.

Not sure how this will translate to the future .formData() to be honest. I’d expect it to act similar to URLSearchParams and never be annotated explicitly.

[florianmatz]

Hey Artem,

mmh, I think both is fair, when made clear.

I personally would prefer the option to type the json() as suggested, because I think when using text() or arrayBuffer() the return value is quite clear and completely ok to be hardcoded. Whereas json() could be any shape and is quite easy inferable…

And you don’t have to use it, if someone likes to stick to a more explicit casting like as Shape (which I don’t prefer, because it always looks like; nah, I just cast it anyways…)

Maybe a compromise could be something like:

json<T>(): Promise<T>

So you put your generic directly and explicitely onto the json()-Method and not onto the complete mocked request… But maybe this is to close to the explicit casting.