Unsafe scopes are forbidden from array's map() function

[kctang]

With rxjs-tslint-rules v4.7.0, and "rxjs-no-unsafe-scope": true, I am getting this rather unexpected "Unsafe scopes are forbidden".

Funny thing is, this whole chunk is NOT about observables.. just normal array map() so I would expect the rules to not take effect.

I only happens when the variable was destructured from parameter (e.g. notOk_mapAnArrayFromParam()). It is ok when used in ok_mapAnArray().

Maybe a bug?

  // this is ok
  ok_mapAnArray () {
    const q = '123'
    return [ 1, 2, 3 ].map(val => {
      // "q" is ok
      return `${q}-${val}`
    })
  }

  notOk_mapAnArrayFromParam (input: { q: string }) {
    const { q } = input
    return [ 1, 2, 3 ].map(val => {
      // "q" is NOT ok - complain about "Unsafe scopes are forbidden"
      return `${q}-${val}`
    })
  }

[cartant]

Yes. This is a bug. The fact that it's const should see it deemed safe. Also, I will have to check the implementation, as I thought it would only be checking observable-related functions - I added a general version of the rule - for any callback - to tslint-etc. It might only be checking the function name and RxJS has a map operator.

[cartant]

Yeah, the implementation looks for RxJS functions by matching names only - not return types. So map is a match. This should probably be fixed, but I think the const destructuring thing is higher priority.

This probably affects other rule implementations, too. Create isObservableFactory/Operator so that custom functions are also supported.

[cartant]

BTW, thanks for opening such details issues. They're really easy to convert into failing tests. Much appreciated.

[cartant]

The const part of this issue should be fixed in 4.7.2 and I've opened a separate issue for the matching-by-name-only behaviour.

[vitalyiegorov]

@cartant Do we have any updates with Array.map?

[cartant]

No. The issue referenced above is still open.