Add tests

[kroeder]

Since we are leaving the proof-of-concept stage we definately need to add tests

[Etienne-Buschong]

This should probably be done as soon as we manage to produce as stable plugin version that runs without problems on our storybook. (Maybe i will start with tests on the side while fixing errors)

[kroeder]

Just a thing that I have thought of and wanted to leave here as a comment:
For CI testing I'd suggest we add a benchmark / smoke test and expect a certain execution time to ensure we don't hurt DX by introducing more advanced features