Description

It's very hard to test our endpoints without messing with global config/environment variables. We should make the endpoint tests dependency-injectable.

A possible path forward:

• the endpoint's functions are defined in separate modules;
• tests use jest.fn or otherwise to mock those functions

Desired behavior/Acceptance criteria (returned value, expected error, performance expectations, etc.)

• tests are insular and easier to express

Completion checklist

• Before closing this task, review one by one the checklist available here: https://www.mediawiki.org/wiki/Abstract_Wikipedia_team/Definition_of_Done#Back-end_Task/Bug_completion_checklist