Add functional recreate revert resize test for bug 1852610

This builds on I644608b4e197ddea31c5f264adb492f2c8931f04 and
adds a revert resize test which deletes the source compute service
while the server is in VERIFY_RESIZE status and then reverts the
resize. The results are a bit different from the confirm scenario
because the confirm fails while the revert actually works which
is more dumb luck based on where the compute service drops the
move claim during the revert process (on the dest which still exists
rather than the source).

Change-Id: I2dcb1cb3e1f8ed469a4c5bf81ca5ca2fcf1fa73c
Related-Bug: #1852610

nova/tests/functional/integrated_helpers.py

@@ -856,6 +856,18 @@ def _migrate_and_check_allocations(self, server, flavor, source_rp_uuid,
             server, request=request, old_flavor=flavor, new_flavor=flavor,
             source_rp_uuid=source_rp_uuid, dest_rp_uuid=dest_rp_uuid)
 
+    def _resize_and_check_allocations(self, server, old_flavor, new_flavor,
+                                      source_rp_uuid, dest_rp_uuid):
+        request = {
+            'resize': {
+                'flavorRef': new_flavor['id']
+            }
+        }
+        self._move_and_check_allocations(
+            server, request=request, old_flavor=old_flavor,
+            new_flavor=new_flavor, source_rp_uuid=source_rp_uuid,
+            dest_rp_uuid=dest_rp_uuid)
+
     def _resize_to_same_host_and_check_allocations(self, server, old_flavor,
                                                    new_flavor, rp_uuid):
         # Resize the server to the same host and check usages in VERIFY_RESIZE

nova/tests/functional/wsgi/test_services.py

@@ -210,6 +210,47 @@ def test_migrate_confirm_after_deleted_source_compute(self):
         self._wait_for_state_change(self.api, server, 'ERROR')
         self.assertIn('ComputeHostNotFound', self.stdlog.logger.output)
 
+    def test_resize_revert_after_deleted_source_compute(self):
+        """Tests a scenario where a server is resized and while in
+        VERIFY_RESIZE status the admin attempts to delete the source compute
+        and then the user tries to revert the resize.
+        """
+        # Start a compute service and create a server there.
+        self._start_compute('host1')
+        host1_rp_uuid = self._get_provider_uuid_by_host('host1')
+        flavors = self.api.get_flavors()
+        flavor1 = flavors[0]
+        flavor2 = flavors[1]
+        server = self._boot_and_check_allocations(flavor1, 'host1')
+        # Start a second compute service so we can resize there.
+        self._start_compute('host2')
+        host2_rp_uuid = self._get_provider_uuid_by_host('host2')
+        # Resize the server to host2.
+        self._resize_and_check_allocations(
+            server, flavor1, flavor2, host1_rp_uuid, host2_rp_uuid)
+        # Delete the source compute service.
+        service = self.admin_api.get_services(
+            binary='nova-compute', host='host1')[0]
+        self.admin_api.api_delete('/os-services/%s' % service['id'])
+        # FIXME(mriedem): This is bug 1852610 where the compute service is
+        # deleted but the resource provider is not because there are still
+        # migration-based allocations against the source node provider.
+        resp = self.placement_api.get('/resource_providers/%s' % host1_rp_uuid)
+        self.assertEqual(200, resp.status)
+        self.assertFlavorMatchesUsage(host1_rp_uuid, flavor1)
+        # Now try to revert the resize.
+        # NOTE(mriedem): This actually works because the drop_move_claim
+        # happens in revert_resize on the dest host which still has its
+        # ComputeNode record. The migration-based allocations are reverted
+        # so the instance holds the allocations for the source provider and
+        # the allocations against the dest provider are dropped.
+        self.api.post_server_action(server['id'], {'revertResize': None})
+        self._wait_for_state_change(self.api, server, 'ACTIVE')
+        self.assertNotIn('ComputeHostNotFound', self.stdlog.logger.output)
+        self.assertFlavorMatchesUsage(host1_rp_uuid, flavor1)
+        zero_flavor = {'vcpus': 0, 'ram': 0, 'disk': 0, 'extra_specs': {}}
+        self.assertFlavorMatchesUsage(host2_rp_uuid, zero_flavor)
+
 
 class ComputeStatusFilterTest(integrated_helpers.ProviderUsageBaseTestCase):
     """Tests the API, compute service and Placement interaction with the