def test_clear_completed(self):
tasks.visit()
tasks.add('a', 'b', 'c')
tasks.toggle('b')
tasks.clear_completed()
tasks.should_be('a', 'c')
def test_filter_tasks(self):
tasks.visit()
tasks.add('a', 'b', 'c')
tasks.should_be('a', 'b', 'c')
tasks.toggle('b')
tasks.filter_active()
tasks.should_be('a', 'c')
tasks.filter_completed()
tasks.should_be('b')