Reproduce that only half of the PCI devs are removed

This reproduces a bug where at each resource tracker
update_available_resources periodic run only half of the remove PCI
devices are deleted from the DB.

Related-Bug: #2115729
Change-Id: I95694f38105d61b4b7befd9223089f3a0d862634
Signed-off-by: Balazs Gibizer <gibi@redhat.com>

nova/tests/unit/pci/test_manager.py

@@ -878,12 +878,25 @@ class PciDevTrackerTestCase(test.NoDBTestCase):
                 self._fake_pci_device_destroy)
         self.destroy_called = 0
         self.assertEqual(len(self.tracker.pci_devs), 3)
-        dev = self.tracker.pci_devs[0]
+        dev1 = self.tracker.pci_devs[0]
+        dev2 = self.tracker.pci_devs[1]
         self.update_called = 0
-        dev.remove()
+        dev1.remove()
+        dev2.remove()
         self.tracker.save(self.fake_context)
+
+        # This is https://bugs.launchpad.net/nova/+bug/2115729 as
+        # only one half of the removed devices are destroyed.
         self.assertEqual(len(self.tracker.pci_devs), 2)
         self.assertEqual(self.destroy_called, 1)
+        # a subsequent save will destroy half of the remaining removed devices
+        self.tracker.save(self.fake_context)
+        self.assertEqual(len(self.tracker.pci_devs), 1)
+        self.assertEqual(self.destroy_called, 2)
+        # after the fix we should see that a single save causes all the
+        # removed devices destroyed
+        # self.assertEqual(len(self.tracker.pci_devs), 1)
+        # self.assertEqual(self.destroy_called, 2)
 
     def test_clean_usage(self):
         inst_2 = copy.copy(self.inst)