[Rule Request] no-promise-in-boolean-expressions

[danielberndt]

We're working with a lot of async/await in our backend code, and the most frequent source of mistake I found in our code base has this shape:

if (user.pictures.exists()) doX()

whereas it should be

if (await user.pictures.exists()) doX()

I'm aware of the strict-boolean-expressions rule, but its ruleset is too strict for our code. So I'm suggesting to create a softer version which allows anything but promises in boolean expressions.

[JoshuaKGoldberg]

but its ruleset is too strict for our code

Specifically which parts? Maybe the rule could have options added that would allow it to be flexible enough for you?

[oleg-codaio]

+1 to the strictness of that rule. We have a lot of code that looks like this:

let maybeObj: SomeObject | undefined = getObj();

if (maybeObj) {
  // do something
}

If this logic was put into that rule, I'd want a rule like "allow-all-unions-except": <symbols> where <symbols> is an array of classes that cannot be in a boolean expression. To handles promises correctly, I'd set that to ["Promise", "Bluebird"] in our codebase.

[oleg-codaio]

I did find something like this elsewhere: https://github.com/wwwouter/tslint-contrib but unfortunately it doesn't support blacklisting additional classes like "Bluebird".

[JoshuaKGoldberg]

Looks like discussion continued a bit deeper in #3983 for a very similar idea. Closing this issue as duplicate; let's continue talking there.

[wclr]

Right, this is a common bug.