add RFC for script run hooks

[deecewan]

This was spurred by yarnpkg/yarn#3209 (comment) to try and normalise the hooks that run and when.

[bestander]

yeah, we don't need shrinkwraps.

[andreineculau]

the shrinkwrap scripts also run when creating the new package-lock.json, so yarn should also run if when creating the yarn.lock file, for a closer 1-to-1 match

[bestander]

Great work, @deecewan!

[bestander]

Let me summon a few folks who have more context

[bestander]

My opinion - this looks fine, we should just match npm@5 and move forward.
Are there any tricks we need to address here?
I remember seeing a few issues where people are expecting to run post/preinstall scripts when reinstalling node_modules.

[deecewan]

AFAIK, from the docs and from testing, I've enumerated how everything works. I might make a couple of test scripts for npm@5 to 'codify' the expected behaviours.

[bestander]

Great job, @deecewan!
Let's do it! Are you up to send a few PRs?
Tests would be very important to make sure we don't regress

[deecewan]

yeah, keen!

I'll do what I can 👍

[andreineculau]

FYI a programmatic comparison of which hooks run and in what order, along with the toold can now be found at https://github.com/andreineculau/package-json-scripts

[bestander]

@deecewan, any chance you've had a crack at this?
@andreineculau, do you want to help out?

[andreineculau]

@bestander I'm both limited by time and incentive as I do not use yarn in my routine. I've done the package-json-scripts investigation because we intend to have git dependencies, and I've seen inconsistencies. My first npm alternative to try out is pnpm actually, so trying out and even committing to yarn is too much in the future.

What I can help out with, no doubt, is doing one final manual testing of whatever new behaviour lands or is about to land in yarn, if nobody wants to run https://github.com/andreineculau/package-json-scripts themselves.

[deecewan]

@bestander i started taking a look at this. yarn already does 95% of theses hooks in the correct order. I went through and figured out which hooks run and when, and then went through yarn and checked on them.

from memory, i think there were only 1 or 2 changes. i'll take another look after work tonight.

[bestander]

@deecewan, awesome, thank you very much.
Do you think you could set up a couple of tests that cover this contract?