Thresholds console output format

[ppcano]

k6 shows the threshold result as a success (✓) or failure (✗).

Given:

  failed_requests: ["rate<0.1"],
  http_req_duration: ["p(95)<500", "p(90)<1500"]

The k6 output could be:

✓ failed_requests............: 0.00%  ✓ 0    ✗ 8970 
✓ http_req_duration..........: avg=131.22ms min=115.29ms med=124.77ms max=260.27ms p(90)=150.87ms p(95)=162.87ms

I suggest a change to the threshold output to show the existing threshold configuration.

Here a suggestion inline with the current format:

failed_requests............: 0.00%  ✓ 0    ✗ 8970
 └─ ✓ rate<0.1 
http_req_duration..........: avg=131.22ms min=115.29ms med=124.77ms max=260.27ms p(90)=150.87ms p(95)=162.87ms
 └─ ✓ p(90)<1500
 └─ ✓ p(95)<500

Showing this information is useful in case you didn't remember the threshold configuration or you changed it between test runs.

[na--]

it's probably a good idea, but we have to consider how this will mesh with sub-metrics and thresholds defined on them. This is also somewhat similar to #1319, and is probably going to get resolved by the summary templates proposed in that issue as well.

[na--]

@ppcano, now that we have handleSummary() (#1768) and k6-summary in jslib, I think I should close this.

In k6 v0.31.0, we want to replace the Go summary generation code with the one from jslib (#1806), so if you think you have a workaround to the issue I raised above, please open a new issue in the jslib repo, or even a PR that adds the desired behavior as an option to generateTextSummary().