More tests

**Is your feature request related to a problem? Please describe.**
As a developer I want a large set of tests to cover around 80% of the code base if possible.
The focus should be on Logic first, Ui and flows second

While I labeled this as "good first issue", take it with a heavy grain of salt, maybe a good first issue for experienced devs? Idk.

**Describe the solution you'd like**
More tests everywhere where needed:
Important are the Blocs, and related code where possible.
- PreparationBloc (currently commented out, due to interface rewrite of FlutterForegroundTask)
- VerificationBloc (currently commented out, [...])

**Describe alternatives you've considered**
Doing everything by hand

**Additional context**
It's needed, even more, if at some point other developers could join the fray.