run coverage using --runInBand, fixes #1109

[fl0w]

Ref jestjs/jest#1874
Fixes #1109

The gist: Jest seems to be writing to cache from two different child processes. It's slower, but doesn't really affect Koa.

I'm expecting this to solve flaky travis tests

[codecov]

Codecov Report

Merging #1141 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1141   +/-   ##
=======================================
  Coverage   99.73%   99.73%           
=======================================
  Files           5        5           
  Lines         372      372           
=======================================
  Hits          371      371           
  Misses          1        1

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e544012...3d27c82. Read the comment docs.

[nickmccurdy]

Nice! It seems like the cron job has already been passing, does this fix some existing problem I'm not noticing or is this is a proactive change?

[fl0w]

It’s a race condition apparently, and so until that issue is closed I’m thinking it’s safe to assume to use the fallback for now.