[strict-boolean-expressions]: New feature, this rule should additionally check value return by callbacks inside Array.some, Array.every, etc

[iliubinskii]

Repro

[1, 2].some(x => x); // Fail

[1, 2].some(x => Boolean(x)); // Ok

Expected Result

With new rule ("strict-array-callback-return-type") should complain about non-boolean return type

[JoshuaKGoldberg]

This seems like a very specific rule tailored to a very specific use-case. Can you give us a bit more info on why you'd like to see this?

We generally avoid adding rules that target unique situations to typescript-eslint core. You can always write your own rule using the APIs described in https://typescript-eslint.io/docs/development/custom-rules.

[iliubinskii]

Can you give us a bit more info on why you'd like to see this?

Sure, this rule has the same motivation as @typescript-eslint/strict-boolean-expressions rule.

Consider the following example:

interface Obj {
  value?: string;
}

function f(x: Obj): void {
  if (x.value) console.log("True");
}

function g(x: Obj[]): void {
  if (x.some(item => item.value)) console.log("True");
}

In the above example function "f" gets warning from "@typescript-eslint/strict-boolean-expressions":

The value returned from calbacks in Array.some, Array.every, etc is also used as condition.
So, it would be good to check it the same way as @typescript-eslint/strict-boolean-expressions checks condition inside "if".
So, what I suggest is that function "g" should get the same warning as function "f" for "item.value".

[iliubinskii]

I have changed subject of this issue, because after writing longer description I see that this should not be a new rule, but rather an additional option to @typescript-eslint/strict-boolean-expressions rule.

[bradzacher]

Duplicate of #1038