fix(platform) instanceof bug between execution contexts of RegExp object

[aesyondu]

First encountered at jest-playwright repo:
playwright-community/jest-playwright#38

Solution based on:
https://stackoverflow.com/questions/4339288/typeof-for-regexp#comment4724685_4339350

[aesyondu]

Also, not sure if this should be modified as well?

playwright/src/page.ts

Line 361 in e658978

if (helper.isString(urlOrPredicate) || urlOrPredicate instanceof RegExp)

playwright/src/page.ts

Line 370 in e658978

if (helper.isString(urlOrPredicate) || urlOrPredicate instanceof RegExp)

[aesyondu]

Not sure how to resolve typescript lint error ##[error]src/platform.ts(226,18): error TS2339: Property 'test' does not exist on type 'RegExp | ((url: URL) => boolean)'.

[JoelEinbinder]

This is because jest overwrites all of the globals right? Would instanceof /./.constructor work then, guaranteeing we get the right regex for this context, not the improper global one. At the same time, jest-playwright should probably add RegExp to the list of globals not to override in jest.

[JoelEinbinder]

Not sure how to resolve typescript lint error ##[error]src/platform.ts(226,18): error TS2339: Property 'test' does not exist on type 'RegExp | ((url: URL) => boolean)'.

typescript does't narrow the type to a regex now that the check is not simple. Cast the variable to a regex before using it. (match as RegEx).test

[msftclas]

All CLA requirements met.

[aesyondu]

I modified the logic and refactored it to helper.ts

Where do I add unit tests? I tried searching unit tests for isNumber and isString but can't find them.

[pavelfeldman]

Where exactly do we pass regex object between contexts? Is this related to the workaround @aslushnikov added before WebKit started accepting multiple collients over the WebSocket?

[JoelEinbinder]

No it’s because jest overrides all globals by default via the vm package.

[JoelEinbinder]

I modified the logic and refactored it to helper.ts

Where do I add unit tests? I tried searching unit tests for isNumber and isString but can't find them.

We always test from the public api. You can use the vm package to get a regex from another context, and verify that you can pass it in as the url match.

[aesyondu]

This is because jest overwrites all of the globals right? Would instanceof /./.constructor work then, guaranteeing we get the right regex for this context, not the improper global one. At the same time, jest-playwright should probably add RegExp to the list of globals not to override in jest.

Btw, if I understood you correctly, I tried:

      const ctx = vm.createContext();
      const regexp = vm.runInContext('new RegExp(/digits\\/\\d\\.png/)', ctx);
      console.log(regexp instanceof RegExp, regexp.constructor instanceof RegExp)

but the output was false, false.

[aslushnikov]

For the record: this already happened to us here - #808 (comment)

but the output was false, false.

Which is exactly what we test against here!

@aesyondu, @JoelEinbinder Is this in a good shape for landing, or am I missing something?

[JoelEinbinder]

Looks great! Thanks for the patch!