[PATCH v2 09/21] avocado/tasst: Add helper to get network interface names for a site

Start adding convenience functions for handling sites as places with
network setup with a simple helper which lists the network interface names
for a site.

Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 avocado/tasst/site.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/avocado/tasst/site.py b/avocado/tasst/site.py
index 61e424c..841efbe 100644
--- a/avocado/tasst/site.py
+++ b/avocado/tasst/site.py
@@ -10,6 +10,8 @@
 # Copyright Red Hat
 # Author: David Gibson <david(a)gibson.dropbear.id.au>
 
+import json
+
 import avocado
 from avocado.utils.process import CmdError
 
@@ -52,6 +54,11 @@ class Site:
             raise avocado.TestCancel("Missing commands {} on {}"
                                      .format(', '.join(missing), self.name))
 
+    def ifs(self):
+        self.require_cmds('ip')
+        info = json.loads(self.output('ip -j link show'))
+        return [i['ifname'] for i in info]
+
 
 class BaseSiteTasst(Tasst):
     """
@@ -94,6 +101,10 @@ class BaseSiteTasst(Tasst):
         status = proc.wait()
         self.assertNotEquals(status, 0)
 
+    def test_has_lo(self):
+        site = self.get_subsetup(BaseSiteTasst)
+        self.assertIn('lo', site.ifs())
+
 
 # Represents the host on which the tests are running, as opposed to
 # some simulated host created by the tests
-- 
2.40.1