rwf2
Add `LocalForm` to make testing with form data more ergonomic
This adds the testing improvement described in #1591.
The transformation of the form fields into the resulting body data is a bit clumsy and could probably use some improvement/cleanup. I believe the multipart form translation is correct, but there's only one, narrow test case that confirms it works as expected.
Additionally, I was unable to get something like this to work without ugly ergonomics:
let client = Client::tracked(rocket).unwrap();
let response = client.post("/")
.form(&[("field", "value"), ("is it", "a cat?")])
.dispatch();
I might be missing something, but attempting to do something like this:
impl<'v, F: Into<ValueField<'v>>, I: Iterator<Item = F>> From<I> for LocalForm { /* .. */ }
requires the caller to call the method in a way similar to this:
client.post("/")
.form(&[("field", "value"), ("is it", "a cat?")].iter().cloned());
due to a slice reference not being coerced into an iterator and when it is iterated over, it returns &(&str, &str). ValueField doesn't have a present From<..> impl for &(&str, &str), so this is not possible.
Also, docs are likely not complete/elaborate enough at this stage, but an attempt at documenting relevant methods/structs was made in this first cut.
Please pick it apart so I can make the implementation better! :)
@SergioBenitez This should be ready for another pass.
I updated the style to better match Rocket's. I think it's mostly there, but there might be some minor style issues remaining.
I changed the writing of the body data to a single Vec<u8> with the write! macro. There's a couple places where I call format!. There's probably a better way than what I did, so any help there would be great!
Error handling is a little weird as it currently silently outputs an empty buffer if the writing failed for some reason. This probably isn't a good user experience because an error would result in empty body data for the form request. Any pointers on how to do better error handling would be great!
