To write functional Apex unit tests for methods having the future annotation, all you need to do is use Test.startTest() and Test.stopTest(). The general structure of your testMethod will look like the following.
Whether it's scheduled Apex or @future Apex, calling Test.stopTest() will cause those methods to run in sequence in your test method. Test.stopTest() then allows you to validate the results of @future Apex using normal means.
