TestNetworkPowerDriver: add test_default_index

This is similar test_create, but it doesn't pass an index value, testing
that the default index of the NetworkPowerPort object is '0' and also
that the NetworkPowerDriver can still be instantiated correctly.

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>

Author: threexc

tests/test_powerdriver.py

@@ -180,6 +180,12 @@ def test_create(self, target):
         d = NetworkPowerDriver(target, 'power')
         assert isinstance(d, NetworkPowerDriver)
 
+    def test_default_index(self, target):
+        r = NetworkPowerPort(target, 'power', model='netio', host='dummy')
+        d = NetworkPowerDriver(target, 'power')
+        assert r.index == '0'
+        assert isinstance(d, NetworkPowerDriver)
+
     @pytest.mark.parametrize('backend', ('rest', 'simplerest'))
     @pytest.mark.parametrize(
         'host',