1765727 - Add comment explaining error.isWebDriverError() uses a name check and not `instanceof`

Status: RESOLVED FIXED

(Remote Protocol :: WebDriver BiDi, enhancement, P3)

Description

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Currently isWebDriverError uses just the name of the error to determine if it's a WebDriver error:

https://searchfox.org/mozilla-central/rev/2fd70a667e6f89a9ec6622ecb302b1ab48e4a062/remote/shared/webdriver/Errors.jsm#109-111

 isWebDriverError(obj) {
    return error.isError(obj) && "name" in obj && ERRORS.has(obj.name);
  },

Instead we should use an instanceof check to determine if the prototype chain of a given object contains the WebDriverError prototype.

Comment 1

[James Graham [:jgraham]]

Note that instanceof could cause a problem if we are ever comparing objects that were created in different globals because they won't have the same prototype object.

Comment 2

[Julian Descottes [:jdescottes]]

As discussed, instanceof is usually dangerous (cross global / cross process etc...), let's just add a comment in the code.

Comment 3

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Attachment: Bug 1765727 - [remote] Add explanation comment to error.isWebDriverError() to explain why not using instanceof.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fd9ec7652acf
[remote] Add explanation comment to error.isWebDriverError() to explain why not using instanceof. r=webdriver-reviewers,jgraham DONTBUILD

Comment 5

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/fd9ec7652acf