Add functional test for "aggregate unset" command

There was not functional test for "aggregate unset"
command, this patch add the test.

Change-Id: Icc8f51e863231e915b2a8cca59baaedd54a96de5

Author: Huanxuan Ao

functional/tests/compute/v2/test_aggregate.py

@@ -57,3 +57,11 @@ def test_aggregate_properties(self):
 
         raw_output = self.openstack('aggregate show ' + self.NAME + opts)
         self.assertIn("a='b', c='d'\n", raw_output)
+
+        raw_output = self.openstack(
+            'aggregate unset --property a ' + self.NAME
+        )
+        self.assertEqual('', raw_output)
+
+        raw_output = self.openstack('aggregate show ' + self.NAME + opts)
+        self.assertIn("c='d'\n", raw_output)