Fix create_server() with a named network

If 'network' was supplied to create_server() along with an empty
'nics' list, we would never attempt to find the network. The os_server
Ansible module uses the API this way. This treats an empty list the
same as if the 'nics' parameter were never supplied.

Change-Id: Idc844fab2c4c08f158c892104d065e5554ed90f3

releasenotes/notes/create_server_network_fix-c4a56b31d2850a4b.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - The create_server() API call would not use the supplied 'network'
+    parameter if the 'nics' parameter was also supplied, even though it would
+    be an empty list. It now uses 'network' if 'nics' is not supplied or if
+    it is an empty list.

shade/openstackcloud.py

@@ -3350,7 +3350,7 @@ class OpenStackCloud(object):
                 raise OpenStackCloudException(
                     'nics parameter to create_server takes a list of dicts.'
                     ' Got: {nics}'.format(nics=kwargs['nics']))
-        if network and 'nics' not in kwargs:
+        if network and ('nics' not in kwargs or not kwargs['nics']):
             network_obj = self.get_network(name_or_id=network)
             if not network_obj:
                 raise OpenStackCloudException(

shade/tests/unit/test_create_server.py

@@ -250,3 +250,28 @@ class TestCreateServer(base.TestCase):
                     OpenStackCloudException, self.client.create_server,
                     'server-name', 'image-id', 'flavor-id',
                     wait=True)
+
+    @patch('shade.OpenStackCloud.nova_client')
+    @patch('shade.OpenStackCloud.get_network')
+    def test_create_server_network_with_no_nics(self, mock_get_network,
+                                                mock_nova):
+        """
+        Verify that if 'network' is supplied, and 'nics' is not, that we
+        attempt to get the network for the server.
+        """
+        self.client.create_server('server-name', 'image-id', 'flavor-id',
+                                  network='network-name')
+        mock_get_network.assert_called_once_with(name_or_id='network-name')
+
+    @patch('shade.OpenStackCloud.nova_client')
+    @patch('shade.OpenStackCloud.get_network')
+    def test_create_server_network_with_empty_nics(self,
+                                                   mock_get_network,
+                                                   mock_nova):
+        """
+        Verify that if 'network' is supplied, along with an empty 'nics' list,
+        it's treated the same as if 'nics' were not included.
+        """
+        self.client.create_server('server-name', 'image-id', 'flavor-id',
+                                  network='network-name', nics=[])
+        mock_get_network.assert_called_once_with(name_or_id='network-name')