New: Configurable List Size For Per-Rule Performance Metrics

[bmish]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[X] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

What changes did you make? (Give an overview)

Implements RFC: https://github.com/eslint/rfcs/tree/master/designs/2020-timing-list-size

Enables the TIMING environment variable to be set to a larger number or all in order to show a longer list of per-rule performance metrics when running eslint from the command line.

Is there anything you'd like reviewers to focus on?

Interested to hear ideas for improving the test coverage.

[mdjermanovic]

Interested to hear ideas for improving the test coverage.

I think testing getListSize is fine for this PR, since we currently don't have tests for the TIMING feature. Once we add unit tests for timing.js we could also modify the tests from this PR to not call getListSize directly (as it seems that it should be an internal function?).

[bmish]

Sounds good.

Another question, should we support both all and ALL as the magic value to remove the limit (basically convert to lowercase before checking it)?

[mdjermanovic]

Another question, should we support both all and ALL as the magic value to remove the limit (basically convert to lowercase before checking it)?

Sounds good to me!

[mdjermanovic]

LGTM, thanks!

[mdjermanovic]

Thanks for contributing!