Hi, this seems much needed. In modern software development you have automated tests that act like a specification to test your contract against. While developing you would like to know if the most crucial behaviors of your contract is still fullfilled. You want a "fixture" where you can load a clean state and test each scenario automatically.
My favorite is Behavior Driven Development and the formulation of test cases in Given/When/Then prases.
For the Egalitarian Contract for example: "GIVEN a 5 members of the DAO, and 2 voted for a contract change. WHEN a third member votes for the contract change, THEN the change should be applied".
Also great for contract audits, you see what is covered and what not by the audit.
First barrier: do I need to instantiate a whole testnet each time I want to run a test?