refactor: embed mochi mqtt broker

backend/iot-server/internal/config/config_test.go

@@ -0,0 +1,34 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadRequiresDeviceCredentials(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "iot.yaml")
+	data := []byte("MQTT:\n  Address: 127.0.0.1:1883\nHTTP:\n  Address: 127.0.0.1:12428\n  InternalToken: test\n")
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Load(path); err == nil {
+		t.Fatal("未配置设备凭证时应拒绝启动")
+	}
+}
+
+func TestLoadDefaultsListenerAndOverridesSingleDevicePassword(t *testing.T) {
+	t.Setenv("HEQI_IOT_MQTT_PASSWORD", "from-secret-store")
+	path := filepath.Join(t.TempDir(), "iot.yaml")
+	data := []byte("MQTT:\n  Address: 127.0.0.1:1883\n  Devices:\n    - ClientID: detector-1\n      DeviceID: '0000000000000001'\n      Username: detector-1\n      Password: placeholder\nHTTP:\n  Address: 127.0.0.1:12428\n  InternalToken: test\n")
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cfg.MQTT.ListenerID != "mqtt-tcp" || cfg.MQTT.Devices[0].Password != "from-secret-store" {
+		t.Fatalf("unexpected MQTT config: %+v", cfg.MQTT)
+	}
+}