Write proper UnitTests

[ottofabian]

Is your feature request related to a problem? Please describe.
Currently the library does not support proper unit tests to verify the functionality.
The demos are hard to interpret without prior knowledge and make it complex to verify that everything still works.

Describe the solution you'd like
Write proper unit test that can be run to ensure functionality.

Describe alternatives you've considered
n.a.

Additional context
n.a.