[BUG] uninstall does not remove --no-save installed package from node_modules

[raphinesse]

Current Behavior:

If I install a package using the --no-save option, it is not removed from node_modules/ upon its uninstallation.

Expected Behavior:

If I install a package using the --no-save option, it should get removed from node_modules/ upon its uninstallation.

NB: this is also how npm 6 behaves.

Steps To Reproduce:

1. Run the following

cd $(mktemp -d)
mkdir node_modules
npm i q --no-save
npm un q --no-save

2. Observe that node_modules/q still exists.

Omitting the --no-save option for the uninstallation command yields the same result. Substituting mkdir node_modules with npm init --yes makes no difference either.

Environment:

• OS: Ubuntu 18.04.5 & 19.10
• Node: 12.19.0 & 15.4.0
• npm: 7.0.15 & 7.1.1

[isaacs]

Confirmed. This appears to be a bug in how we're handling the fake {} package we use when there's no package.json in the root project, combined with using the actualTree as the effective starting idealTree when there's no package-lock.json present. If there's either a package.json or a package-lock.json that declares the deps present, it does properly remove them. If neither of those are there, it doesn't properly remove the dependency.