My only comment here is instead of rejecting/throwing when we're unable to set the badge count, I wonder if we should just resolve the promise with false (and with true when we are successful). In general I think rejecting should be reserved for actual errors and exceptions, and here we expect a fair amount of devices in production to have this failure -- which developers have no control over. Also, there's not really any alternative to this behavior so I think most developers would just catch the error and then do nothing. (or have an unhandled promise rejection) --> resolving with false is better and people can handle it if they want to.

This would also take care of the weird test case -- we can just expect either true or false and the test will only fail if an actual exception occurs.