Fake token needs generating in memory for `TwitterServiceTest`

[JSn1nj4]

In simplifying parts of App\Services\Twitter\TwitterService, it seems I inadvertently broke a few tests. These tests now directly depend on there being a token already. I've temporarily copied some code into multiple test cases to fix them, but this isn't a good permanent solution.

Maybe this can be solved with helper functions for 2 specific scenarios:

• tests that fake connecting to the token API endpoint
• tests that need a token already existing in the DB

The following test cases currently depend on there being a token saved in DB storage:

• 'creates an instance of App\Services\Twitter\TwitterService'
• 'throws an exception if requested tweet count is < 1'
• 'throws an exception if requested tweet count is > 3200'
• 'processes a response from the twitter api user timeline endpoint

[JSn1nj4]

This class needs refactoring. These issues will immediately become easier if the token can be injected.

[JSn1nj4]

Fixed by 6b0eb7f.