Integration tests

[nobe4]

Currently the unit tests are working as expected but it would be better to have integration tests.

• Write a simple web server that serves pages of notifications
• Use it to mock the API
• Write custom fixtures to tests various cases of success and failures
• Add more tests
  • Retry
  • Cache update
  • Done state
  • Hidden state
  • Error handling
• Find a way to test also the actions