Switch to Mocha

Reopening this, since it looks like one of our other issues got closed. I looked into test frameworks a bit more.

• ava seems awesome, but I’m concerned with its concurrent nature. I’d imagine our tests involve modifying state on disk, so concurrently running tests each modifying disk state could be a big issue. If ava has a good workaround for this (other than the .serial method for every test case, which sounds like a pain), feel free to correct me.
• mocha is pretty popular, and runs things concurrently. That’s a bit slower than ava since it’s not in parallel, but should be more than fast enough.
• rocha seems pretty promising. This is a wrapper on top of mocha (so it’s still running tests concurrently), but it runs them in a random order (this makes sure we don’t have a dependency between different test cases). If we get a random order that fails, rocha will keep that order until we get the tests to pass (so it’s still easy to debug issues). If we’re starting from scratch, it should be easy to write tests that don’t depend on order.

I don’t care too much which framework we use, as long as it works and ties into coverage tools. I’m mostly posting this as a reminder that we need some sort of unit tests.

[levithomason]

thanks for the bump, will put some time to this tonight.

[levithomason]

PR up #31