From d4fcd1fa0e2d6a90d49a84ba7d4426607053da51 Mon Sep 17 00:00:00 2001
From: Gong Zhang <zhanggbj@cn.ibm.com>
Date: Mon, 29 Jul 2019 17:39:19 +0800
Subject: [PATCH] Report an error if no flag(s) set in service update

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()