Ask HN: How do you test your SDN Codebase

For those that that build SDN components in the data plane, I have a few questions for you:

1 - Which tools do you use on a daily basis to do functional testing of your SDN components ? (For example, how do you test that a jitteriness on the underlying physical network doesn't cause crazy behaviour in your code? Or high level of packet drop? Or non-standard TCP implementations going thru your code? or .... you name it)

2 - How much of your Quality Assurance/Control processes are automated vs. manually done ? (rough estimate)

3 - What infrastructure do you use to run your automated tests (Do you have a private cluster? Public cloud? Kubernetes Cluster? ....)

4 - What advise would you give a new comer to the field of SDN data plane development?