Skip VIF api tests for old api versions

This patch ensures that VIF api tests are not launched on installations
with unsupported Ironic API version < 1.28.

Change-Id: I6f562aed6307915fb5ff158b91bdb595d62f1f6f
Related-Bug: #1655888
diff --git a/ironic_tempest_plugin/tests/api/admin/test_nodes.py b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
index e7cfa8b..bf37ca8 100644
--- a/ironic_tempest_plugin/tests/api/admin/test_nodes.py
+++ b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
@@ -168,6 +168,17 @@
         self.assertEqual(1, len(body['nodes']))
         self.assertIn(self.node['uuid'], [n['uuid'] for n in body['nodes']])
 
+
+class TestNodesVif(base.BaseBaremetalTest):
+
+    min_microversion = '1.28'
+
+    def setUp(self):
+        super(TestNodesVif, self).setUp()
+
+        _, self.chassis = self.create_chassis()
+        _, self.node = self.create_node(self.chassis['uuid'])
+
     @test.idempotent_id('a3d319d0-cacb-4e55-a3dc-3fa8b74880f1')
     def test_vifs(self):
         self.useFixture(