Implement Backend Testing & Logic Fixes

[DavideIadeluca]

Fixes #80

Changes proposed in this pull request:

• Write backend tests
• Fix discovered issues

Reviewers should focus on:
I'm thinking of changing the condition of lurking by removing the requirement that the last post needs to be read.

follow-tags/src/Jobs/SendNotificationWhenReplyIsPosted.php

Line 65 in 0834d19

->where('discussion_user.last_read_post_number', '>=', $this->lastPostNumber - 1)

The translation of lurking Be notified of all new discussions and replies is currently kind of misleading. I would expect to receive notifications no matter if I've read previous posts in a discussion or not. Opinions?

Screenshot

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).

Required changes:

• Related Flarum core extension PR's: (Omit this section if irrelevant)