CI: add caching.

[XhmikosR]

If any of the following files changes, the cache will be invalidated:

• package.json
• package-lock.json
• .github/workflows/ci.yml

This can probably be simplified but it should be a first start. Feel free to push any further changes to this branch.

[XhmikosR]

I think I will remove this so that when one of the above files change cache is invalidated. Better have this as a fallback mechanism. WDYT?

[mikemimik]

Hey @XhmikosR from our understanding of the caching action we're not sure we would see any benefits.

The rational being, with the key combination of {os}-{node-version}-{package.json} we never run npm install more than once on the same job in an action. This combination would generate a unique key for each item in the matrix of action runs. If we simplified it by removing {os} then it would be stating that the same npm cache could be used for windows and linux, which isn't something we'd want. By removing {node-version} then we'd have the same cache across node versions, which isn't ideal either.

I think at the moment we'll forgo adding a cache to the CI specifically in npm/cli as there is only one job for each action in the matrix, and this one job only runs npm install once anyhow.

This is definitely an improvement we'll want to look at in the future if testing and coverage get a little more involved, and perhaps in some of the dependencies of the npm/cli project itself.

Thanks so much for the suggestion, we didn't know that there was a caching action available! 👍🏽

(I'm closing the comment, but not the conversation. Please reach out if you think we've made a mistake)

[XhmikosR]

Just FYI this is almost the same logic Travis CI is using.

The benefits aren't huge, I agree. But this could tweaked further as needed.