What are best practices for testing against stateful data?

[caithammer]

What are best practices for testing against stateful data? How should we incorporate this into contributor guidelines? Ex: If you made a change to script that creates the analysis table that viz is built on, you can't test script for bugs (dropping data, formatting column)

[CharlotteJackson]

I've tried to address this by creating a test database postgres_dev. We can go over how to use it at this upcoming project night.