Generate test scaffold?

[jamestalmage]

If I add test generation support, I will probably do it as a sub-generator.

I see two test scenarios:

• Full blown test with AVA. Helpful if you plan to ship the codemod.
• Simple tests using just assert module and logging statements (no runner). Stays true to the "install no additional dependencies" goal, and is useful for quickly testing/debugging a throwaway codemod.