test: abstract skip functionality to common

[Fishrock123]

Checklist

• tests and code linting passes
• a test and/or benchmark is included
• the commit message follows commit guidelines

Affected core subsystem(s)

test

Description of change

The tap skipping output is so prevalent yet obscure in nature that we ought to move it into it's own function in test/common.js

cc @nodejs/testing

[Fishrock123]

Oops, still need to fix these!

[Fishrock123]

Here's the actual function in test/common.js: https://github.com/nodejs/node/pull/6697/files#diff-8736c5cbff21e1dee18b0c86d3d2689dR468

[Fishrock123]

CI: https://ci.nodejs.org/job/node-test-pull-request/2592/ (Green)

[Trott]

LGTM if CI has no complaints

[santigimeno]

LGTM

[Trott]

Nit: It might be good to name the function more precisely, as it does not actually skip. It outputs the TAP-formatted skip message. I would expect skip() to exit the process too. So either add process.exit() to skip() or else change the function to something like printSkipTapOutput() (although that's not exactly aesthetically pleasing).

Totally a nit, feel free to ignore, I know process.exit() causes some trepidation in some situations, and I'm fine with this as it is.

[Fishrock123]

Maybe just printSkip(msg)? Idk

[Fishrock123]

The reason I went with this is iirc because it causes a skip even if the test fails afterwards?

[Trott]

The more I think about it, I wouldn't expect a common.whatever() call to exit my process anyway, so it's probably a bad suggestion.

[indutny]

LGTM

[MylesBorins]

@Fishrock123 I'm going to put this in dont-land-in-lts but please feel free to do a manual backport

[Fishrock123]

Huh. Backporting doesn't seem to work at all. 10 obscure errors.

I'll just redo the patch for v4.x, it shoudn't be difficult, and this will likely cause backport conflicts if we don't.

[MylesBorins]

@Fishrock123 that's what I figured would happen. Totally up for the manual backport thanks 👍

[Fishrock123]

backport @ #7114