599 switch from chai to jest

[doxthree]

• Removed chai and mocha as dep
• Add Jest as new dep
• Apply new testing scheme

NOTE: Jest also warns about open handles when running:

jest --forceExit --detectOpenHandles

Jest has detected the following 3 open handles potentially keeping Jest from exiting:

For this case, I would skip this but we should have a look at this in the future.

[unglaublicherdude]

Nice. I like it. Thank you for putting in the work!