Skip background tests earlier if topology does not support

When the topology does not support background tests (either ping or
iperf), the tests are skipped. Before this patch, the stacks required by
these tests were created, despite not being used later, and this
was a waste of resources.

Change-Id: I60ef10276cf175d7d9cc3b5a2da54f221068acd1

tobiko/openstack/topology/_topology.py

@@ -333,6 +333,8 @@ class OpenStackTopology(tobiko.SharedFixture):
         neutron.SERVER: 'devstack@q-svc',
     }
 
+    background_tests_supported = False
+
     def __init__(self):
         super(OpenStackTopology, self).__init__()
         self._names: typing.Dict[str, OpenStackTopologyNode] = (

tobiko/rhosp/_topology.py

@@ -59,6 +59,8 @@ class RhospTopology(topology.OpenStackTopology):
     has_containers = True
     container_runtime_cmd = 'podman'
 
+    background_tests_supported = True
+
     @property
     def ignore_containers_list(self):
         return None

tobiko/tests/scenario/neutron/test_network.py

@@ -68,6 +68,14 @@ class BackgroundProcessTest(BaseNetworkTest):
 
     stack = tobiko.required_fixture(stacks.AdvancedPeerServerStackFixture)
 
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.topology = topology.get_openstack_topology()
+        if not cls.topology.background_tests_supported:
+            tobiko.skip_test(
+                'Background tests not supported by this topology class.')
+
     def test_check_background_vm_ping(self):
         """ Tests that are designed to run in the background ,
             then collect results.
@@ -75,7 +83,8 @@ class BackgroundProcessTest(BaseNetworkTest):
             then execute some check logic i.e. a check function.
             if the process by name isn't running,
             start a separate process i.e a background function"""
-        topology.get_openstack_topology().check_or_start_background_vm_ping(
+
+        self.topology.check_or_start_background_vm_ping(
             self.stack.peer_stack.floating_ip_address)
 
     def test_east_west_tcp_traffic_background_iperf(self):
@@ -86,8 +95,7 @@ class BackgroundProcessTest(BaseNetworkTest):
         Traffic is send in the single flow using "iperf" tool.
         """
 
-        topology.get_openstack_topology().\
-            check_or_start_background_iperf_connection(
+        self.topology.check_or_start_background_iperf_connection(
                 self.stack.fixed_ipv4,
                 port=5203,
                 protocol='tcp',
@@ -102,8 +110,7 @@ class BackgroundProcessTest(BaseNetworkTest):
         Traffic is send in the single flow using "iperf" tool.
         """
 
-        topology.get_openstack_topology().\
-            check_or_start_background_iperf_connection(
+        self.topology.check_or_start_background_iperf_connection(
                 self.stack.peer_stack.floating_ip_address,
                 port=5204,
                 protocol='tcp',