Add Testing to track (breaking) changes

[Srylax]

Description

Before updating to newer version of mongodb, tests need to be in place so that breaking changes can be easier detected.

Behaviour changes

Old: Currently there are no tests in place.

New: Introduce various tests. This includes public api testing, happy path testing, doc tests, proptests and unit testing. This helps to familiarize with the code.

Category

This is related to a:

• [ ] Bugfix
• [x] Feature
• [ ] Packaging
• [x] Docs
• [x] Code Quality
• [x] Refactoring
• [ ] Miscellaneous

Tests

• [ ] Unit-Tests were created
• [ ] Code is already covered by Unit-Tests
• [ ] No tests required