1. Build iOS app.
2. Open mariadb shell and execute `select * from olm_sessions;`. Remember the `version` column value of the last session.
3. Send a couple of collapsible notifications.
4. Execute `select * from olm_sessions;`. Ensure last session version column value didn't change.
5. Update `FUTURE_CODE_VERSION` to 0.
6. Send a couple of collapsible notifications. Ensure that coalescing takes place.
7. Execute `select * from olm_sessions;`. Ensure last session version column value increased by the number of sent notifications.