Single spec helper - we're not dealing with a Rails app, let's not stress too much.
Heroku has been pushing 'heroku run rake' over 'heroku rake' for a while now.
Simpler version constraints.
Spec directory structure becomes a little more standard.
Remove unused change method.
Faraday middleware instead of wrapper methods.
Acceptance testing with local Pusher interaction.

With thanks to a local EventMachine-driven server fired up for each test. Insane, but it works. And the test implementation isn't amazingly ugly, which is a nice surprise.