Nodegroup min_node_count should default to 0

This changes the default value for nodegroups min_node_count to 0.
Scaling nodegroups to 0 is also allowed.

Change-Id: I74dd0d34990b71b290b6ccbe707afb8cc7ae7340
Depends-On: Id63459d0fe9836e678bb7569f23d29eabc225e9e
story: 2007851
task: 40147

magnumclient/osc/v1/nodegroups.py

@@ -78,7 +78,7 @@ class CreateNodeGroup(command.Command):
         parser.add_argument('--min-nodes',
                             dest='min_node_count',
                             type=int,
-                            default=1,
+                            default=0,
                             metavar='<min-nodes>',
                             help='The nodegroup minimum node count.')
         parser.add_argument('--max-nodes',

magnumclient/tests/osc/unit/v1/test_clusters.py

@@ -499,6 +499,21 @@ class TestClusterResize(TestCluster):
             "UUID1", 2, None, None
         )
 
+    def test_cluster_resize_to_zero_pass(self):
+        arglist = ['foo', '0']
+        verifylist = [
+            ('cluster', 'foo'),
+            ('node_count', 0),
+            ('nodes_to_remove', None),
+            ('nodegroup', None)
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+
+        self.cmd.take_action(parsed_args)
+        self.clusters_mock.resize.assert_called_with(
+            "UUID1", 0, None, None
+        )
+
 
 class TestClusterUpgrade(TestCluster):
 

magnumclient/tests/osc/unit/v1/test_nodegroups.py

@@ -47,7 +47,7 @@ class TestNodeGroupCreate(TestNodeGroup):
             'name': 'fake-nodegroup',
             'node_count': 1,
             'role': 'worker',
-            'min_node_count': 1,
+            'min_node_count': 0,
             'max_node_count': None,
         }
 

magnumclient/tests/v1/test_nodegroups.py

@@ -37,7 +37,7 @@ NODEGROUP1 = {
     'is_default': True,
     'role': 'worker',
     'max_node_count': 10,
-    'min_node_count': 1
+    'min_node_count': 0
 }
 NODEGROUP2 = {
     'id': 124,
@@ -53,7 +53,7 @@ NODEGROUP2 = {
     'is_default': True,
     'role': 'master',
     'max_node_count': 10,
-    'min_node_count': 1
+    'min_node_count': 0
 }
 
 CREATE_NODEGROUP = copy.deepcopy(NODEGROUP1)