Missing tests for for await (async of

[Zalathar]

It was recently noticed (babel/babel#13235) that Babel failed to parse this code:

async function f() {
    for await (async of []);
}

Unlike a regular for-of loop there is no ambiguity with for (async of => {};;), and an async function expression is not legal here, so async can be used as the loop variable.

But it's easy for the implementation to mess up by parsing async of as an async function anyway, or by incorrectly sharing code that prohibits for (async of in a regular for-of.

[jugglinmike]

That sounds like a meaningful test case to me. Thanks for the report!

Would you like to write the test? I'm available to help you get started if you need a hand.

[Zalathar]

I was able to write some test cases based on the existing templates in src/dstr-binding-for-await/default/, but I'm a bit lost on where to put them (since they aren't destructuring?) or what documentation they need.

I guess I should just submit a draft PR with what I have so far?

[jugglinmike]

Great! I'm happy to give feedback on a work-in-progress.

Since this issue is orthogonal to the parsing of destructuring patterns, using those templates may produce a lot of tests which aren't meaningfully distinctive for implementers. This sounds like a case for hand-written tests, but we can discuss that in the context of your patch if you prefer.

[bakkot]

The PR which added tests for other cases may be useful context.