[BUG] `npm uninstall -g` doesn't run the `preuninstall` script

[Goobles]

Current Behavior:

npm uninstall -g <package> doesn't run the preuninstall script

Also, npm install -g <package> doesn't run the preuninstall script from the previously installed version of the same package

Installing a newer version of a global package does trigger preuninstall in v6

Expected Behavior:

npm uninstall -g <package> should run the preuninstall script

Steps To Reproduce:

Since npm7 removed console output for scripts during installation, so I echo something to a logfile instead.

1. Create a package with these scripts:

{
  "name": "testpackage",
  "version":"0.0.1",
  "scripts": {
    "preinstall": "echo \"preinstall\" >> /logs/log.txt",
    "preuninstall": "echo \"preuninstall\" >> /logs/log.txt"
  }
}

2. run npm pack
3. run npm install -g ./testpackage-0.0.1.tgz
4. run npm install -g ./testpackage-0.0.1.tgz again (this should have triggered preuninstall for the previous installation)
5. run npm uninstall -g testpackage
6. confirm that the text file in /logs/log.txt does in fact not contain any 'preuninstall' lines

Images:
In v7:

In v6:

Environment:

• OS: Windows 10
• Node: 15.14.0
• npm: 7.7.6

[wraithgar]

by design, npm does not have any lifecycle events/scripts that run during uninstall. I would agree that they should be there, but we would have to discuss it as part of our RFC process.

@darcyclarke can we add this issue to the next RFC call?

[darcyclarke]

@wraithgar I wasn't aware that this was a design decision(?) This definitely did work in v6 (was able to replicate below), feels like a legitimate bug but I could be wrong...

v6.14.12

v7.9.0

Our docs explicitly point out uninstall as a lifecycle event (ref. https://docs.npmjs.com/cli/v7/using-npm/scripts#examples) that will run... which doesn't seem to be working either; I also can't find any documentation on a decision to remove this in our changelog, code or RFCs - so it may just be that it was an oversight & we need to add those events explicitly back into rebuild.js when removing a dep from arborist...

[Goobles]

Some packages depend on a preuninstall hook: winser documents it to add and remove background processes on install/uninstall.

I personally use it for an in-house cli tool that installs a local rest api that runs in the background at all times. When installing a new version this service needs to be uninstalled as to not cause file lock issues in Windows, and reinstalled so a newer version of this api is spun up. This is now causing issues in npm7.

[wraithgar]

@wraithgar I wasn't aware that this was a design decision(?) This definitely did work in v6 (was able to replicate below), feels like a legitimate bug but I could be wrong...

Good catch. I was looking at the Lifecyle Operation Order Which doesn't mention uninstall at all. The only place uninstall is mentioned is in that example itself.

I agree this is now an arborist bug.