Fix MODULE_NOT_FOUND

[dekimsey]

Description

By default the working directory of the composite action is the calling workflows's context. This means a relative require like what was done here isn't reading the action's embedded main.js but instead trying to read main.js in the caller's workflow.

This presented as an error message like such:

Error: Cannot find module '/home/runner/work/eng-serv-cron/eng-serv-cron/main.js'
Require stack:
- /home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)
    at Object.apply (/home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15186:27)
    at eval (eval at callAsyncFunction (/home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15143:16), <anonymous>:3:8)
    at callAsyncFunction (/home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15144:12)
    at main (/home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15236:26)
    at /home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15217:1
    at /home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js:15268:3 {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
    '/home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js'
  ]
}
Error: Unhandled error: Error: Cannot find module '/home/runner/work/eng-serv-cron/eng-serv-cron/main.js'
Require stack:
- /home/runner/work/_actions/actions/github-script/d7906e4ad0b1822421a7e6a35d5ca353c962f410/dist/index.js

This wasn't caught during testing because GHA requires one to check the testing repo out before being able to run a local action. This masked the behavior as our checkout directory was always the same as the action we were testing.

I believe it was missed in the integration tests because those were tested when the main.js content was embedded in the action.yml.

Resolution

• This PR fixes the original issue by using absolute pathing to load the main.js from the action's source tree as originally intended.
• We also add a test to validate this will not occur in the future. The workflow must load a hard-coded uses, so we execute against main after a PR is closed. This allows us to validate the action will work in the exact same way our calling workflows might use it.
• Submitted a PR to document this in github/actions-script#368.

Note: github.action_path would be the correct Node variable to retrieve the action's source directory, but there's discussion about this being broken for the moment. Instead we'll use process.env.GITHUB_ACTION_PATH, until actions/runner#2517 is fixed.

[jeanneryan]

LGTM