minor fixes

e2e/mock_e2e.sh

@@ -11,8 +11,11 @@ readonly cluster_name="kind-test-postgres-operator"
 # avoid interference with previous test runs
 if [[ $(kind get clusters | grep "^${cluster_name}*") != "" ]]
 then
+  # true if variable is set; bash >= v4.2
+  if [[ -v KUBECONFIG ]];then 
       rm "$KUBECONFIG"
       unset KUBECONFIG
+  fi
   kind delete cluster --name ${cluster_name}
 fi
 

e2e/tests.py

@@ -33,7 +33,7 @@ class SampleTestCase(unittest.TestCase):
             if v1_node_var.metadata.labels['lifecycle-status'] == 'ready':
                 labelled_nodes.add(v1_node_var.metadata.name)
 
-        assert self.nodes == labelled_nodes, "nodes incorrectly labelled"
+        self.assertEqual(self.nodes, labelled_nodes,"nodes incorrectly labelled")
 
     def tearDown(self):
         """