Fix tests

[leggsimon]

Todo:

• [x] Update Makefile to actually run unit tests so they get run on CI
• [x] Fix the existing test suite
• [ ] Add tests for all files in /src/utils
  • [ ] db.js
  • [ ] flags.js
  • [ ] handlers.js
  • [x] low-res-image.js
  • [x] map-key-match.js
  • [x] navigate.js (this is actually a commented out file so considering it done. Will check if it can be removed)
  • [x] offline-content.js
  • [x] parse-link-headers.js
  • [ ] personal.js
  • [ ] precache.js
  • [ ] route.js

  • [ ] router.js

    Note I have changed the return value for offline-content.js and low-res-image.js. In order for them to just do one thing, as well as to make them easier to test, they no longer return fetch promises they now return a String and a Response object respectively. I have updated their usage here and here.

[wheresrhys]

Excellent it passes :+1: :+1:

I still think the stuff we worked on the other day to convert a lot of the tests that weren't same domain to same domain tests needs doing, but one step at a time

[tavvy]

Great :+1: