Add a test that the timer is removed after unmount?

[alexkrolick]

Just a thought 😄. Probably want to test that no dangling intervals or timeouts are left behind after unmount.

[donavon]

good thought. looks like there is a jest.getTimerCount() that I can use for just that purpose.

'cuz, ya know, you can't have too many tests for a 10 line package ☺️