[regression] find-cache-dir 3.3.0, used through nyc+mocha, causes creation of a folder tree ./false/find-cache-dir/ containing js files

[ronjouch]

I have a Mocha test suite, code-coveraged by Nyc, run inside Shippable CI with the following command: NODE_ENV=test nyc --reporter=cobertura --report-dir=../shippable/codecoverage/ mocha --exit --require ./config/mocha.js --recursive test --timeout 80000 --ui bdd -R xunit --reporter-options output=../shippable/testresults/maestro.xml .

• Using find-cache-dir@3.2.0, tests pass and no folder is created in cwd.
• After re-creating my project's package-lock.json, I got find-cache-dir@3.3.0 (which makes semver sense, since nyc 15.0.0 depends on "find-cache-dir": "^3.2.0"), tests pass, but running the tests now cause creation of a spurious folder named false, itself containing a folder named find-cache-dir, containing js named <myOriginalFilename>-<some kind of hash>.js:

false/find-cache-dir/fields-9e2a8b3608c81ff79e5dab523ca0a8c95035eaa14ec95ca88bdc922d0a8e8666.js
false/find-cache-dir/config-a10b75b822f09c2a3fe51c8f4ab42b7a09609eb1a9c065eeb30f475f7049dc2c.js
false/find-cache-dir/index-21c01eca85d0b02b6011525dd4934129ef0384a5aaf6e5a7989eb7c43db9f5e3.js
... [59 other files]

• After manually reverting only find-cache-dir to 3.2.0 in the package-lock (editing the package lock to use the old version & hash), the problem disappears.

I cannot reproduce the issue on my local dev. machine, the issue only arises on Shippable CI. I don't know why yet.

The project uses a package-lock, guaranteeing the only difference is the find-cache-dir version. So, the regression must lie in v3.2.0...v3.3.0 .

Node 12.15.0, Nyc 15.0.0, Mocha 7.1.0. Project is closed source and I cannot share it, sorry. I hope the regression window is enough to find a fix, as I'm unable to reproduce the issue locally and it would be difficult for me to provide a minimal & reliably-reproducible test case.

Thanks.

[sindresorhus]

// @Richienb

[Richienb]

@ronjouch In your environment, what is process.env.CACHE_DIR set to?

[ronjouch]

In your environment, what is process.env.CACHE_DIR set to?

@Richienb oh wow. This is a beautiful bug 😄. Good catch, you're right. In Shippable CI, CACHE_DIR is by default set to false. See Shippable docs - Environment variables - Standard variables:

CACHE_DIR If cache is true in the build section of shippable.yml, then true. Otherwise false.

→ Given this is a still a very new feature: with appropriate communication to initial users and a major semver break, would a less collision-prone env. var (e.g. FIND_CACHE_DIR) make sense?

[Richienb]

@sindresorhus

[sindresorhus]

I think we should just gracefully handle this. If the value is true/false/1/0, we don’t use the environment variable.