Do not sort subnet dns_nameservers field

When using table output format, the dns_nameservers field
of a subnet is sorted, but it should not be as the order
is important.

Created an UnsortedListColumn() class in subnet.py so the
output is correct.

Updated the unit test accordingly to verify the order is
correct when an entry is removed.

Change-Id: I60a15a944f83549738305dd025db38ff8e165be7
Closes-bug: #2053201

Author: brianphaley

openstackclient/network/v2/subnet.py

@@ -60,9 +60,16 @@ def human_readable(self):
         )
 
 
+class UnsortedListColumn(cliff_columns.FormattableColumn):
+    # format_columns.ListColumn sorts the output, but for things like
+    # DNS server addresses the order matters
+    def human_readable(self):
+        return ', '.join(self._value)
+
+
 _formatters = {
     'allocation_pools': AllocationPoolsColumn,
-    'dns_nameservers': format_columns.ListColumn,
+    'dns_nameservers': UnsortedListColumn,
     'host_routes': HostRoutesColumn,
     'service_types': format_columns.ListColumn,
     'tags': format_columns.ListColumn,

openstackclient/tests/unit/network/v2/test_subnet.py

@@ -167,7 +167,7 @@ def _init_subnet_variables(self):
             subnet_v2.AllocationPoolsColumn(self._subnet.allocation_pools),
             self._subnet.cidr,
             self._subnet.description,
-            format_columns.ListColumn(self._subnet.dns_nameservers),
+            subnet_v2.UnsortedListColumn(self._subnet.dns_nameservers),
             self._subnet.enable_dhcp,
             self._subnet.gateway_ip,
             subnet_v2.HostRoutesColumn(self._subnet.host_routes),
@@ -190,7 +190,9 @@ def _init_subnet_variables(self):
             ),
             self._subnet_from_pool.cidr,
             self._subnet_from_pool.description,
-            format_columns.ListColumn(self._subnet_from_pool.dns_nameservers),
+            subnet_v2.UnsortedListColumn(
+                self._subnet_from_pool.dns_nameservers
+            ),
             self._subnet_from_pool.enable_dhcp,
             self._subnet_from_pool.gateway_ip,
             subnet_v2.HostRoutesColumn(self._subnet_from_pool.host_routes),
@@ -213,7 +215,7 @@ def _init_subnet_variables(self):
             ),
             self._subnet_ipv6.cidr,
             self._subnet_ipv6.description,
-            format_columns.ListColumn(self._subnet_ipv6.dns_nameservers),
+            subnet_v2.UnsortedListColumn(self._subnet_ipv6.dns_nameservers),
             self._subnet_ipv6.enable_dhcp,
             self._subnet_ipv6.gateway_ip,
             subnet_v2.HostRoutesColumn(self._subnet_ipv6.host_routes),
@@ -236,7 +238,7 @@ def _init_subnet_variables(self):
             ),
             self._subnet_ipv6_pd.cidr,
             self._subnet_ipv6_pd.description,
-            format_columns.ListColumn(self._subnet_ipv6_pd.dns_nameservers),
+            subnet_v2.UnsortedListColumn(self._subnet_ipv6_pd.dns_nameservers),
             self._subnet_ipv6_pd.enable_dhcp,
             self._subnet_ipv6_pd.gateway_ip,
             subnet_v2.HostRoutesColumn(self._subnet_ipv6_pd.host_routes),
@@ -837,7 +839,7 @@ class TestListSubnet(TestSubnet):
                 subnet.cidr,
                 subnet.project_id,
                 subnet.enable_dhcp,
-                format_columns.ListColumn(subnet.dns_nameservers),
+                subnet_v2.UnsortedListColumn(subnet.dns_nameservers),
                 subnet_v2.AllocationPoolsColumn(subnet.allocation_pools),
                 subnet_v2.HostRoutesColumn(subnet.host_routes),
                 subnet.ip_version,
@@ -1489,7 +1491,7 @@ class TestShowSubnet(TestSubnet):
         subnet_v2.AllocationPoolsColumn(_subnet.allocation_pools),
         _subnet.cidr,
         _subnet.description,
-        format_columns.ListColumn(_subnet.dns_nameservers),
+        subnet_v2.UnsortedListColumn(_subnet.dns_nameservers),
         _subnet.enable_dhcp,
         _subnet.gateway_ip,
         subnet_v2.HostRoutesColumn(_subnet.host_routes),
@@ -1550,9 +1552,10 @@ def test_show_all_options(self):
 class TestUnsetSubnet(TestSubnet):
     def setUp(self):
         super(TestUnsetSubnet, self).setUp()
+        # Add three dns_nameserver entries so we can verify ordering
         self._testsubnet = network_fakes.FakeSubnet.create_one_subnet(
             {
-                'dns_nameservers': ['8.8.8.8', '8.8.8.4'],
+                'dns_nameservers': ['8.8.8.8', '8.8.8.4', '8.8.4.4'],
                 'host_routes': [
                     {'destination': '10.20.20.0/24', 'nexthop': '10.20.20.1'},
                     {'destination': '10.30.30.30/24', 'nexthop': '10.30.30.1'},
@@ -1578,9 +1581,10 @@ def setUp(self):
         self.cmd = subnet_v2.UnsetSubnet(self.app, self.namespace)
 
     def test_unset_subnet_params(self):
+        # Remove just the middle dns_nameserver entry, verify still in order
         arglist = [
             '--dns-nameserver',
-            '8.8.8.8',
+            '8.8.8.4',
             '--host-route',
             'destination=10.30.30.30/24,gateway=10.30.30.1',
             '--allocation-pool',
@@ -1591,7 +1595,7 @@ def test_unset_subnet_params(self):
             self._testsubnet.name,
         ]
         verifylist = [
-            ('dns_nameservers', ['8.8.8.8']),
+            ('dns_nameservers', ['8.8.8.4']),
             (
                 'host_routes',
                 [{"destination": "10.30.30.30/24", "gateway": "10.30.30.1"}],
@@ -1605,7 +1609,7 @@ def test_unset_subnet_params(self):
         result = self.cmd.take_action(parsed_args)
 
         attrs = {
-            'dns_nameservers': ['8.8.8.4'],
+            'dns_nameservers': ['8.8.8.8', '8.8.4.4'],
             'host_routes': [
                 {"destination": "10.20.20.0/24", "nexthop": "10.20.20.1"}
             ],