support password-protected vercel deployments

[JoshBarr]

Hey @patrickedqvist, thanks for making this library!

I'm sure you love unsolicited PRs as much as any other maintainer 😅 Apologies in advance!

We've been looking for a way to run our e2e tests against the preview URL for a while. We password protect all our preview deployments, so we needed a way sign in programmtically inside the action.

Here's a summary of what's changed:

Functional changes

• Adds support for a vercel_password input, which is used to obtain a _vercel_jwt cookie for browsing authenticated sites.
• Since we're going to the trouble of parsing the JWT, we make it available as an output, so that it can passed on to e2e tests.

bug fixes

• Fixed an issue where the deployment notification would never resolve, if there was another non-vercel deployment running in another workflow on the same PR. We look up the deployment that's triggered by vercel[bot] rather than just taking the first deployment.
• Fixed a couple of minor flow control things, where the code would keep running after setFailure(), which sometimes resulted in double errors

dev experience and CI

• Adds a prettier config
• Added a few unit tests with Jest and MockServiceWorker
• Adds a workflow for running the unit tests
• Dropped the node_modules from the package, in favour of compiling the project with ncc. This is apparently how GitHub build most of their actions.

[patrickedqvist]

@JoshBarr Thank you so much for your contribution!

Unsolicited PRs are more than welcome since I don't always have the time to add new features myself. I scrolled through your changes which looks good but I'm going to make a more thorough review soon.

[JoshBarr]

Thanks Patrick! Let me know if there's things I can improve, clarify or change to fit with your plans for this library, too! :)

I've updated the test workflow to include code coverage reporting:

If you re-run the workflow (it needs approval), we should get an automatic comment on the PR with our coverage metrics.

[JoshBarr]

It looks like the coverage reporting step failed. I've reverted that change for now.

[JoshBarr]

I fixed another edge case: when fetching the initial list of deployments for the PR, it's possible that the wait-for-vercel action gets triggered before vercel has reported its first deployment status. I've modified the action so that it waits for a deployment to show up from vercel[bot] before checking the status of it.