From 8fbb51f92aaf379cf29c4406ba8bca8631850ae6 Mon Sep 17 00:00:00 2001
From: Gong Zhang <zhanggbj@cn.ibm.com>
Date: Thu, 1 Aug 2019 04:49:44 +0800
Subject: [PATCH] Report an error if no flag(s) set in service update (#318)

For now if no flag(s) set, service update will still try to
do an update, it should return an error instead.

[issue 286](https://github.com/knative/client/issues/286)
---
 pkg/kn/commands/service/service_update.go     | 13 +++++++++++-
 .../commands/service/service_update_test.go   | 20 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/pkg/kn/commands/service/service_update.go b/pkg/kn/commands/service/service_update.go
index 39260977ef..c0aac2bda8 100644
--- a/pkg/kn/commands/service/service_update.go
+++ b/pkg/kn/commands/service/service_update.go
@@ -29,7 +29,7 @@ func NewServiceUpdateCommand(p *commands.KnParams) *cobra.Command {
 	var waitFlags commands.WaitFlags
 
 	serviceUpdateCommand := &cobra.Command{
-		Use:   "update NAME",
+		Use:   "update NAME [flags]",
 		Short: "Update a service.",
 		Example: `
   # Updates a service 'mysvc' with new environment variables
@@ -91,6 +91,9 @@ func NewServiceUpdateCommand(p *commands.KnParams) *cobra.Command {
 				return nil
 			}
 		},
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			return preCheck(cmd, args)
+		},
 	}
 
 	commands.AddNamespaceFlags(serviceUpdateCommand.Flags(), false)
@@ -98,3 +101,11 @@ func NewServiceUpdateCommand(p *commands.KnParams) *cobra.Command {
 	waitFlags.AddConditionWaitFlags(serviceUpdateCommand, 60, "Update", "service")
 	return serviceUpdateCommand
 }
+
+func preCheck(cmd *cobra.Command, args []string) error {
+	if cmd.Flags().NFlag() == 0 {
+		return errors.New(fmt.Sprintf("flag(s) not set\nUsage: %s", cmd.Use))
+	}
+
+	return nil
+}
diff --git a/pkg/kn/commands/service/service_update_test.go b/pkg/kn/commands/service/service_update_test.go
index 76aed4bae2..3a832447d6 100644
--- a/pkg/kn/commands/service/service_update_test.go
+++ b/pkg/kn/commands/service/service_update_test.go
@@ -88,6 +88,26 @@ func fakeServiceUpdate(original *v1alpha1.Service, args []string, sync bool) (
 	return
 }
 
+func TestServcieUpdateNoFlags(t *testing.T) {
+	orig := newEmptyService()
+
+	action, _, _, err := fakeServiceUpdate(orig, []string{
+		"service", "update", "foo"}, false)
+
+	if action != nil {
+		t.Errorf("Unexpected action if no flag(s) set")
+	}
+
+	if err == nil {
+		t.Fatal(err)
+	}
+
+	expectedErrMsg := "flag(s) not set"
+	if !strings.Contains(err.Error(), expectedErrMsg) {
+		t.Fatalf("Missing %s in %s", expectedErrMsg, err.Error())
+	}
+}
+
 func TestServiceUpdateImageSync(t *testing.T) {
 	orig := newEmptyService()