Thorough backend tests

[Rocked03]

We're missing tests for most of the backend routes and services. It'd be good to get a thorough set of test cases going.

[Rocked03]

Have moved to the backlog for now-- this would be a reasonably push to the codebase so it's probably worth waiting until after the event and doing this in the off-season

[Rocked03]

Include end-to-end testing

[stijnvdkolk]

Would like to pick this up after the event concludes :) unless someone else really wants to pick it up 🚀

[Rocked03]

All yours :)

[stijnvdkolk]

In progress with #735 :)