Improve tests

[bryanbraun]

Just a few thoughts I had while looking at this.

• We could use more tests... especially covering the core functionality. For example:
  1. Verify that when the media query enters X that "entry" methods are run.
  2. Verify that when the media query exits X that "exit" methods are run.
  3. Verify that when the media query enters or exits X that "both" methods are run.
• It would be nice if PRs made to this repo automatically ran the tests using something like TravisCI. You could set that up using something like this: https://gist.github.com/bryanbraun/4a955cc30c394f137b0d
  • Update: this is now set up with CircleCI