feat(mux): Add AckUnknownSubjects option

Adds the AckUnknownSubjects field to the HandlerMux struct. This
controls the default behaviour when there is no registred handler
for the incoming event subject.

Author: zapling

handler_mux.go

@@ -3,11 +3,15 @@ package cone
 import "fmt"
 
 func NewHandlerMux() *HandlerMux {
-	return &HandlerMux{handlers: make(map[string]Handler)}
+	return &HandlerMux{
+		AckUnknownSubjects: false,
+		handlers:           make(map[string]Handler),
+	}
 }
 
 type HandlerMux struct {
-	handlers map[string]Handler
+	AckUnknownSubjects bool
+	handlers           map[string]Handler
 }
 
 func (h *HandlerMux) Handle(subject string, handler Handler) {
@@ -45,6 +49,9 @@ func (h *HandlerMux) Serve(r Response, e *Event) {
 func (h *HandlerMux) serveEvent(r Response, e *Event) error {
 	handler, ok := h.handlers[e.Subject]
 	if !ok {
+		if h.AckUnknownSubjects {
+			return r.Ack()
+		}
 		return r.Nak()
 	}
 

handler_mux_test.go

@@ -151,6 +151,16 @@ func TestServe(t *testing.T) {
 		}
 	})
 
+	t.Run("Unregistred event should ack if AckUnknownSubjects=true is set", func(t *testing.T) {
+		c := cone.NewHandlerMux()
+		c.AckUnknownSubjects = true
+		r := conetest.NewRecorder()
+		c.Serve(r, conetest.NewEvent("not.wanted", nil))
+		if r.Result() != conetest.Ack {
+			t.Errorf("Expected %s but got: %s", conetest.Ack, r.Result())
+		}
+	})
+
 	t.Run("Registred event should ack", func(t *testing.T) {
 		c := cone.NewHandlerMux()
 		c.HandleFunc("is.wanted", func(_ cone.Response, _ *cone.Event) {})