Add "repeat" option to "sigh test".

[shaper]

Have to emulate currently, with unnecessary overhead for each run and no built-in summary of pass/fail, via something like:

'for i in `seq 10`; do ./tools/sigh test --grep='demo'; done'

@mmandlis @dstockwell

[lindner]

Potential steps:

• Add a new command line option to sigh.js
• Find the magic mocha repeat or numtimes api.

[shaper]

@mykmartin I recall you'd found a way to use the mocha repeat through double-double-hyphens or something but I can't find it now.

[mykmartin]

@shaper Not that I can recall... webdriver has the mochaOpts flag, so you can do this sort of thing: npm run test-wdio -- --mochaOpts.grep 'gl.*'

But that's not applicable to the standard command-line tests run by sigh.

[thebrianchen]

Is the ultimate goal to optionally retry tests 'n' times until it passes, or to run tests repeatedly to determine flakiness/test latency?

[shaper]

My intent was the latter: "run tests repeatedly to determine flakiness/test latency". We do need a summary of output, I see that's been mentioned on the PR. Since otherwise we can basically effect with the shell command at the start of this issue.

[lindner]

I think we can mark this done. You can run a large number of tests to determine flakiness and you get a summary of output. Thanks so much @thebrianchen