Remove unusable `--broker` flag from `trigger update` cmd (#1847)

* Remove unusable  flag from  cmd

* Fix unit test

docs/cmd/kn_trigger_update.md

@@ -24,7 +24,6 @@ kn trigger update NAME
 ### Options
 
 ```
-      --broker string      Name of the Broker which the trigger associates with. (default "default")
       --filter strings     Key-value pair for exact CloudEvent attribute matching against incoming events, e.g type=dev.knative.foo
   -h, --help               help for update
   -n, --namespace string   Specify the namespace to operate in.

pkg/kn/commands/trigger/update_flags.go

@@ -50,7 +50,10 @@ func (f *TriggerUpdateFlags) GetUpdateFilters() (map[string]string, []string, er
 
 // Add is to set parameters
 func (f *TriggerUpdateFlags) Add(cmd *cobra.Command) {
-	cmd.Flags().StringVar(&f.Broker, "broker", "default", "Name of the Broker which the trigger associates with.")
+	if cmd.Name() != "update" {
+		// Spec.Broker is immutable field
+		cmd.Flags().StringVar(&f.Broker, "broker", "default", "Name of the Broker which the trigger associates with.")
+	}
 	// The Sugar controller was integrated into main Eventing controller. With that the default behavior was changed as well.
 	// Users need to configure 'Automatic Broker Creation' per linked docs.
 	// Deprecated in 1.4, remove in 1.6.

pkg/kn/commands/trigger/update_test.go

@@ -62,20 +62,6 @@ func TestTriggerUpdateWithError(t *testing.T) {
 	eventingRecorder.Validate()
 }
 
-func TestTriggerUpdateInvalidBroker(t *testing.T) {
-	eventingClient := clienteventingv1.NewMockKnEventingClient(t)
-	eventingRecorder := eventingClient.Recorder()
-	present := createTrigger("default", triggerName, map[string]string{"type": "dev.knative.new"}, "mybroker", "newsvc")
-	eventingRecorder.GetTrigger(triggerName, present, nil)
-
-	out, err := executeTriggerCommand(eventingClient, nil, "update", triggerName,
-		"--broker", "newbroker")
-	assert.ErrorContains(t, err, "broker is immutable")
-	assert.Assert(t, util.ContainsAll(out, "Usage", triggerName))
-
-	eventingRecorder.Validate()
-}
-
 func TestTriggerUpdateDeletionTimestampNotNil(t *testing.T) {
 	eventingClient := clienteventingv1.NewMockKnEventingClient(t)