docs: Note that GHA doesn't support any caching for pnpm

[bmulholland]

Ideally there'd be an official recommendation or something here, but of course I can't speak to that.

See also cypress-io/github-action#1044

[netlify]

👷 Deploy request for cypress-docs pending review.

Visit the deploys page to approve it

Name	Link
🔨 Latest commit	ffa5770

[CLAassistant]

All committers have signed the CLA.

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[MikeMcC399]

This may be a bug rather than missing functionality. It needs further investigation.

• The original PR feat: add support for pnpm (install and cache deps) github-action#586 intended to cache dependencies. Possibly there has been a change since the original support of pnpm, perhaps in the caching mechanisms on the side of GitHub or on the side of pnpm affecting how dependencies are stored.

[bmulholland]

AFAICT the issue is that, while deps are cached, Cypress installs binaries in a place that is cached. The official cypress.io recommendation is to cache that binary install location, too, but then the two can get out of sync. When they do, you may have the package cache, but not the binary cache, and then the job would fail.

There's a silly-obvious approach of "give me a command to run that fetches the binaries if they don't exist," which is what playwright has for browsers. Cypress seems fixed on maintaining the magical "npm install"-only experience, and that leads to this problem.

[MikeMcC399]

@bmulholland

• Cypress doesn't install browsers.

• The cypress-io/github-action can use browsers made available through GitHub Actions images, such as ubuntu-22.04, through Docker images such as cypress/browsers or browsers installed by other means.

• I've opened a new issue Provide pnpm workflow caching without action enhancement github-action#1227 and hope that we can make some progress there in providing guidance on caching in pnpm environments.

[bmulholland]

Yeah sorry, I mis-typed. The "browser" part is actually the Cypress binary. The substance of my comment remains the same.

[MikeMcC399]

@bmulholland

Yeah sorry, I mis-typed. The "browser" part is actually the Cypress binary. The substance of my comment remains the same.

Perhaps you could edit your post and substitute the correct terms in that case? I may have misunderstood you even given the substitution, but pnpm cypress install is the command that will install the Cypress binary if it is missing.

A caching recommendation has been re-instated. See
https://github.com/cypress-io/github-action/blob/master/README.md#pnpm

[MikeMcC399]

This PR adds text to an example using npm, not pnpm, so it would need more explanation to cover npm, Yarn and pnpm at this point.

I would defer to https://github.com/cypress-io/github-action/blob/master/README.md for all detailed information and try to keep the description on the docs site simple.

The comment about cache advisory is no longer true:

The Cypress Github Action does not do any caching for pnpm, and
[advises not to use any caching of any form](https://github.com/cypress-io/github-action?tab=readme-ov-file#pnpm).

My preference would be to not pursue this PR further.