fix parse resource in setting selector

hack/make-rules/test-cmd-util.sh

@@ -2435,6 +2435,9 @@ run_service_tests() {
   # prove role=master
   kube::test::get_object_assert 'services redis-master' "{{range$service_selector_field}}{{.}}:{{end}}" "redis:master:backend:"
 
+  # Set selector of a local file without talking to the server
+  kubectl set selector -f examples/guestbook/redis-master-service.yaml role=padawan --local -o yaml "${kube_flags[@]}"
+  ! kubectl set selector -f examples/guestbook/redis-master-service.yaml role=padawan --dry-run -o yaml "${kube_flags[@]}"
   # Set command to change the selector.
   kubectl set selector -f examples/guestbook/redis-master-service.yaml role=padawan
   # prove role=padawan
@@ -2443,6 +2446,10 @@ run_service_tests() {
   kubectl set selector -f examples/guestbook/redis-master-service.yaml app=redis,role=master,tier=backend
   # prove role=master
   kube::test::get_object_assert 'services redis-master' "{{range$service_selector_field}}{{.}}:{{end}}" "redis:master:backend:"
+  # Show dry-run works on running selector
+  kubectl set selector services redis-master role=padawan --dry-run -o yaml "${kube_flags[@]}"
+  ! kubectl set selector services redis-master role=padawan --local -o yaml "${kube_flags[@]}"
+  kube::test::get_object_assert 'services redis-master' "{{range$service_selector_field}}{{.}}:{{end}}" "redis:master:backend:"
 
   ### Dump current redis-master service
   output_service=$(kubectl get service redis-master -o json --output-version=v1 "${kube_flags[@]}")

pkg/kubectl/cmd/set/set_selector.go

@@ -116,6 +116,10 @@ func (o *SelectorOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args [
 	mapper, _ := f.Object()
 	o.mapper = mapper
 	o.encoder = f.JSONEncoder()
+	o.resources, o.selector, err = getResourcesAndSelector(args)
+	if err != nil {
+		return err
+	}
 
 	o.builder = f.NewBuilder(!o.local).
 		ContinueOnError().
@@ -135,8 +139,6 @@ func (o *SelectorOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args [
 	o.ClientForMapping = func(mapping *meta.RESTMapping) (resource.RESTClient, error) {
 		return f.ClientForMapping(mapping)
 	}
-
-	o.resources, o.selector, err = getResourcesAndSelector(args)
 	return err
 }