Remove test_init_nonexist_schedulerdriver

oslo.config will ensure option [sheduler]/driver with parameter choices
only allow values in ("filter_scheduler", "caching_scheduler",
"chance_scheduler", "fake_scheduler"), so don't need test in Nova.

Change-Id: Ia876e5f85dc5b9a293985fe850e73c455b07847c

nova/tests/unit/scheduler/test_scheduler.py

@@ -18,7 +18,6 @@
 """
 
 import mock
-import testtools
 
 from nova import context
 from nova import objects
@@ -64,14 +63,6 @@ def test_init_using_caching_schedulerdriver(self,
         driver = self.manager_cls().driver
         self.assertIsInstance(driver, caching_scheduler.CachingScheduler)
 
-    @mock.patch.object(host_manager.HostManager, '_init_instance_info')
-    @mock.patch.object(host_manager.HostManager, '_init_aggregates')
-    def test_init_nonexist_schedulerdriver(self,
-                                           mock_init_agg,
-                                           mock_init_inst):
-        with testtools.ExpectedException(ValueError):
-            self.flags(driver='nonexist_scheduler', group='scheduler')
-
 
 class SchedulerManagerTestCase(test.NoDBTestCase):
     """Test case for scheduler manager."""