Unit tests for GET requests

[asc2683]

• [ ] Add unit tests for GET requests
  • [ ] GET teams /api/teams
  • [ ] GET teamMembers /api/teamMembers
  • [ ] GET specific team /api/team/:id
  • [ ] GET specific team /api/teamMember/:id

Resource: https://facebook.github.io/jest/docs/en/tutorial-async.html