Feature Request: Allow caching with the standalone instrument command

[AndrewFinlay]

Problem

The nyc instrument command could benefit from using a cache. This would speed up subsequent runs of nyc instrument that were using the same cache and be a big benefit to streaming instrumentation implementations.

Proposal

Add the caching options from the standard nyc command to nyc instrument

[coreyfarrell]

I'm not strictly opposed to this idea but we'd need to be sure that any options which can alter results (such as --require) are properly handled for cache invalidation.

[AndrewFinlay]

I've put up the start of a PR, it allows the instrument command to access the cache but doesn't do anything about cache invalidation. I was thinking of collecting any relevant settings and storing them in a file that would trigger a cache clean if the stored settings didn't match the current settings. Anyway I'm open to advice on how to implement this.

[coreyfarrell]

I wonder if we add nycInstrumentCache to getInvalidatingOptions in lib/hash.js? This would force nyc instrument to cache to different filenames from normal nyc execution if. I assume you would use nyc --no-instrument when running your actual tests since the files are already transpiled so this shouldn't be an issue for performance.

Probably wouldn't hurt to also add require to the list in lib/hash.js but that wouldn't be adequate on it's own. The problem is how many people pass the --require options for mocha, I can say many do this based on the number of bugs about inconsistent --all coverage for TypeScript in nyc < 15.

[stale]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[AndrewFinlay]

bump. Still relevant, from memory this needs work to finish.

[stale]

Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[AndrewFinlay]

bump, Still relevant, I'll take another look when there's some maintainer interest