Maintain consistent units in CLI output

[mcandre]

Please display consistent units, e.g. deci-second precision, in order to reduce visual jitter during performance runs.

[na--]

You can change the time unit with summaryTimeUnit / --summary-time-unit / K6_SUMMARY_TIME_UNIT option, for example k6 run --summary-time-unit=ms script.js. That should help somewhat, even though there are no deci-seconds (only s, ms and us for now). You also currently can't specify the decimal precision or the left padding of the numbers, so alignment may still not be perfect if you have high variability.

Improving the alignment of the end-of-test summary in general is tracked in #1024. Also, we're currently working on a way to export the end-of-test summary in a JSON format, so follow #1168 if you want to know when you'd be able to do it and format it however it works for you.

All of that said, I don't know if we should just always use milliseconds by default when displaying the metric values in the end-of-test summary... It will probably be a better UX to not mix µs and ms values at least, that's the most annoying part for me personally. But some metrics like iteration_duration and group_duration will likely have much larger values than the http_req_* metrics, sometimes in the tens or hundreds of seconds, which doesn't make sense to display as milliseconds... 😕 So, maybe we should just stick to having a mix of ms and s values, unless the user explicitly requests microseconds by --summary-time-unit=us?

[na--]

I'm closing this issue, now that we have handleSummary() in k6 v0.30.0 (#1768), this can be left entirely at the discretion of the user.

An in any case, as I mentioned in #1806, in k6 v0.31.0 we'll adopt the latest version of the JS-based summary generation code from jslib.k6.io, originally submitted in grafana/jslib.k6.io#20. So any change requests for the default text summary k6 outputs should be opened in https://github.com/loadimpact/jslib.k6.io/issues now.