Fix the request context in ServiceFixture

Multiple cells are not considered in ServiceFixture.
So all compute nodes are registered to only one cell (cell1)
database regardless of their cells.
So change the ServiceFixture to use a request context
for the cell where the service runs.

Closes-Bug: #1759792

Change-Id: I6e940518c6ec27c02c714db6c124eb88c72214ab
(cherry picked from commit 6a06fd28c2)

nova/test.py

@@ -409,6 +409,7 @@ class TestCase(testtools.TestCase):
             CONF.set_override(k, v, group)
 
     def start_service(self, name, host=None, **kwargs):
+        cell = None
         if name == 'compute' and self.USES_DB:
             # NOTE(danms): We need to create the HostMapping first, because
             # otherwise we'll fail to update the scheduler while running
@@ -424,7 +425,7 @@ class TestCase(testtools.TestCase):
                 # Make sure that CONF.host is relevant to the right hostname
                 self.useFixture(nova_fixtures.ConfPatcher(host=host))
         svc = self.useFixture(
-            nova_fixtures.ServiceFixture(name, host, **kwargs))
+            nova_fixtures.ServiceFixture(name, host, cell=cell, **kwargs))
 
         return svc.service
 

nova/tests/fixtures.py

@@ -65,7 +65,7 @@ SESSION_CONFIGURED = False
 class ServiceFixture(fixtures.Fixture):
     """Run a service as a test fixture."""
 
-    def __init__(self, name, host=None, **kwargs):
+    def __init__(self, name, host=None, cell=None, **kwargs):
         name = name
         # If not otherwise specified, the host will default to the
         # name of the service. Some things like aggregates care that
@@ -73,12 +73,18 @@ class ServiceFixture(fixtures.Fixture):
         host = host or name
         kwargs.setdefault('host', host)
         kwargs.setdefault('binary', 'nova-%s' % name)
+        self.cell = cell
         self.kwargs = kwargs
 
     def setUp(self):
         super(ServiceFixture, self).setUp()
-        self.service = service.Service.create(**self.kwargs)
-        self.service.start()
+        self.ctxt = context.get_admin_context()
+        if self.cell:
+            context.set_target_cell(self.ctxt, self.cell)
+        with mock.patch('nova.context.get_admin_context',
+                        return_value=self.ctxt):
+            self.service = service.Service.create(**self.kwargs)
+            self.service.start()
         self.addCleanup(self.service.kill)