[FEATURE] Added fixtures for units

__Tasks:__
- [x] refactored ORM fixtures
- [x] added fixtures for units
- [x] got feedback

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

hm?