virt: refactor method compute_driver_matches

We only use method compute_driver_matches for checking if compute_driver
equals 'xenapi.XenAPIDriver'. To be explicit, just rename it to is_xenapi.

Change-Id: I2fb61491c4a321ab430f39476127412d8ee17c0d

nova/block_device.py

@@ -510,7 +510,7 @@ def instance_block_mapping(instance, bdms):
     root_device_name = instance['root_device_name']
     # NOTE(clayg): remove this when xenapi is setting default_root_device
     if root_device_name is None:
-        if driver.compute_driver_matches('xenapi.XenAPIDriver'):
+        if driver.is_xenapi():
             root_device_name = '/dev/xvda'
         else:
             return _DEFAULT_MAPPINGS

nova/compute/utils.py

@@ -136,7 +136,6 @@ def get_next_device_name(instance, device_name_list,
     /dev/vdc is specified but the backend uses /dev/xvdc), the device
     name will be converted to the appropriate format.
     """
-    is_xen = driver.compute_driver_matches('xenapi.XenAPIDriver')
 
     req_prefix = None
     req_letter = None
@@ -157,7 +156,7 @@ def get_next_device_name(instance, device_name_list,
         raise exception.InvalidDevicePath(path=root_device_name)
 
     # NOTE(vish): remove this when xenapi is setting default_root_device
-    if is_xen:
+    if driver.is_xenapi():
         prefix = '/dev/xvd'
 
     if req_prefix != prefix:
@@ -171,7 +170,7 @@ def get_next_device_name(instance, device_name_list,
 
     # NOTE(vish): remove this when xenapi is properly setting
     #             default_ephemeral_device and default_swap_device
-    if is_xen:
+    if driver.is_xenapi():
         flavor = instance.get_flavor()
         if flavor.ephemeral_gb:
             used_letters.add('b')

nova/tests/unit/compute/test_compute_utils.py

@@ -48,7 +48,7 @@ import nova.tests.unit.image.fake
 from nova.tests.unit.objects import test_flavor
 from nova.tests.unit.objects import test_migration
 from nova.tests import uuidsentinel as uuids
-from nova.virt import driver
+
 
 CONF = nova.conf.CONF
 CONF.import_opt('compute_manager', 'nova.service')
@@ -288,19 +288,9 @@ class DefaultDeviceNamesForInstanceTestCase(test.NoDBTestCase):
         self.root_device_name = '/dev/vda'
         self.update_called = False
 
-        def fake_driver_matches(driver_string):
-            if driver_string == 'libvirt.LibvirtDriver':
-                return self.is_libvirt
-            return False
-
         self.patchers = []
         self.patchers.append(
                 mock.patch.object(objects.BlockDeviceMapping, 'save'))
-        self.patchers.append(
-                mock.patch.object(driver,
-                                  'compute_driver_matches',
-                                  new=mock.Mock(
-                                      side_effect=fake_driver_matches)))
         for patcher in self.patchers:
             patcher.start()
 

nova/tests/unit/virt/test_driver.py

@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from oslo_config import fixture as fixture_config
+
 from nova import test
 from nova.virt import driver
 
@@ -56,3 +58,24 @@ class ToDriverRegistryTestCase(test.NoDBTestCase):
             drvs['key2'],
             FakeDriver2, 'arg1', 'arg2', param1='value1',
             param2='value2')
+
+
+class DriverMethodTestCase(test.NoDBTestCase):
+
+    def setUp(self):
+        super(DriverMethodTestCase, self).setUp()
+        self.CONF = self.useFixture(fixture_config.Config()).conf
+
+    def test_is_xenapi_true(self):
+        self.CONF.set_override('compute_driver', 'xenapi.XenAPIDriver',
+                               enforce_type=True)
+        self.assertTrue(driver.is_xenapi())
+
+    def test_is_xenapi_false(self):
+        driver_names = ('libvirt.LibvirtDriver', 'fake.FakeDriver',
+                        'ironic.IronicDriver', 'vmwareapi.VMwareVCDriver',
+                        'hyperv.HyperVDriver', None)
+        for driver_name in driver_names:
+            self.CONF.set_override('compute_driver', driver_name,
+                                   enforce_type=True)
+            self.assertFalse(driver.is_xenapi())

nova/virt/driver.py

@@ -1626,5 +1626,5 @@ def load_compute_driver(virtapi, compute_driver=None):
         sys.exit(1)
 
 
-def compute_driver_matches(match):
-    return CONF.compute_driver and CONF.compute_driver.endswith(match)
+def is_xenapi():
+    return CONF.compute_driver == 'xenapi.XenAPIDriver'