How testing is done in event-bus implementations

## Description
Some comments I've gathered from the [community survey](https://docs.google.com/forms/d/e/1FAIpQLSc5_Qad-KkduhWpxuLk0wk4YVO8AxjHZ9DeVYbVzcLqSFzYzg/viewform?usp=pp_url) on the challenges/suggestions section:

> Maybe some documentation about how the testing is done with the avro schemas and what happens under the hood.