Use a more sophisticated template for end-to-end testing of Create React App

Created by: gaearon

We currently test the same template we generate by default, which is probably file, but we miss out on testing more advanced features. Ideally we should have a kitchensink template that uses all possible features (JSX, Flow, NODE_PATH, generators, async/await, class properties etc), and make sure that that template builds and passes tests.

If you’d like to work on it, please write in this issue so others don’t duplicate effort. The task would consist of:

Looking at tasks/e2e.sh and learning how we test CRA
Figuring out how to make it use a different template just for e2e test—not sure how I’d do that so suggestions welcome
Creating that kitchensink template