package config

import "testing"

func TestValidateRejectsDeviceIDThatCannotFormTopic(t *testing.T) {
	cfg := Config{}
	cfg.MQTT.URL = "mqtt://127.0.0.1:18883"
	cfg.MQTT.ClientID = "lab-client"
	cfg.MQTT.Username = "backend"
	cfg.MQTT.Password = "lab-password"
	cfg.MQTT.DeviceID = "device!001"
	cfg.App.ConnectTimeout = "10s"

	if err := cfg.Validate(); err == nil {
		t.Fatal("Validate accepted a device ID rejected by the topic contract")
	}
}