Create skip_if_is_old_ovn decorator

It assumes that old OVN configuration will not have the two
agents we typically use to recognise OVN and OVS configurations

 has OVS agent: -> is OVS (OSP 13 or OSP 16+)
 has OVN agent: -> is OVN (OSP 16+)
 has any agent: -> is OVN (OSP 13)

Change-Id: I2588ebe38aeb9e07026abe5585085335d377ea89

tobiko/openstack/neutron/__init__.py

@@ -41,7 +41,7 @@ list_networking_agents = _agent.list_networking_agents
 skip_if_missing_networking_agents = _agent.skip_if_missing_networking_agents
 skip_unless_is_ovn = _agent.skip_unless_is_ovn
 skip_unless_is_ovs = _agent.skip_unless_is_ovs
-
+skip_if_is_old_ovn = _agent.skip_if_is_old_ovn
 
 NeutronClientFixture = _client.NeutronClientFixture
 ServiceUnavailable = _client.ServiceUnavailable

tobiko/openstack/neutron/_agent.py

@@ -14,6 +14,7 @@
 from __future__ import absolute_import
 
 import collections
+import re
 import typing
 
 import tobiko
@@ -101,9 +102,14 @@ DecoratorType = typing.Callable[[typing.Union[typing.Callable, typing.Type]],
                                 typing.Union[typing.Callable, typing.Type]]
 
 
-def skip_if_missing_networking_agents(binary: typing.Optional[str] = None,
-                                      count: int = 1, **params) -> \
-        DecoratorType:
+AgentBinaryType = typing.Union[str, typing.Pattern[str]]
+
+
+def skip_if_missing_networking_agents(
+        binary: AgentBinaryType = None,
+        count: int = 1,
+        **params) \
+        -> DecoratorType:
     if binary is not None:
         params['binary'] = binary
     message = "missing {return_value!r} agent(s)"
@@ -115,8 +121,9 @@ def skip_if_missing_networking_agents(binary: typing.Optional[str] = None,
 
 
 def skip_unless_missing_networking_agents(
-        binary: typing.Optional[str] = None,
-        count: int = 1, **params) \
+        binary: AgentBinaryType = None,
+        count: int = 1,
+        **params) \
         -> DecoratorType:
     if binary is not None:
         params['binary'] = binary
@@ -128,6 +135,12 @@ def skip_unless_missing_networking_agents(
                               **params)
 
 
+def skip_if_is_old_ovn():
+    """Skip the test if OVN is not configured"""
+    binary = re.compile(f'({OPENVSWITCH_AGENT}|{OVN_CONTROLLER})')
+    return skip_if_missing_networking_agents(binary)
+
+
 def skip_unless_is_ovn():
     """Skip the test if OVN is not configured"""
     return skip_unless_missing_networking_agents(OPENVSWITCH_AGENT)