Reproducer unit test for bug 1860312

Consider the following situation:

- Using the Ironic virt driver
- Replacing (so removing and re-adding) all baremetal nodes
  associated with a single nova-compute service

The update resources periodic will have destroyed the compute node
records because they're no longer being reported by the virt driver.
If we then attempt to manually delete the compute service record, the
datbase layer will raise an exception, as there are no longer any
compute node records for the host. This exception gets bubbled up as
an error 500 in the API. This patch adds a unit test to demonstrate
this.

Related bug: 1860312
Change-Id: I03eec634b25582ec9643cacf3e5868c101176983
(cherry picked from commit 32257a2)
(cherry picked from commit e6cd23c)

Author: notartom

nova/tests/unit/api/openstack/compute/test_services.py

@@ -701,6 +701,25 @@ def test_services_delete(self, mock_get_compute_nodes):
         mock_get_compute_nodes.assert_called_once_with(
             self.req.environ['nova.context'], compute.host)
 
+    @mock.patch(
+        'nova.objects.ComputeNodeList.get_all_by_host',
+        side_effect=exception.ComputeHostNotFound(host='fake-compute-host'))
+    def test_services_delete_compute_host_not_found(
+            self, mock_get_all_by_host):
+        compute = objects.Service(self.ctxt,
+                                  **{'host': 'fake-compute-host',
+                                     'binary': 'nova-compute',
+                                     'topic': 'compute',
+                                     'report_count': 0})
+        compute.create()
+        # FIXME(artom) Until bug 1860312 is fixed, the ComputeHostNotFound
+        # error will get bubbled up to the API as an error 500.
+        self.assertRaises(
+            webob.exc.HTTPInternalServerError,
+            self.controller.delete, self.req, compute.id)
+        mock_get_all_by_host.assert_called_with(
+            self.req.environ['nova.context'], 'fake-compute-host')
+
     def test_services_delete_not_found(self):
 
         self.assertRaises(webob.exc.HTTPNotFound,