feat(go): expose nats bridge pending metrics

go/vehicle-gateway/cmd/nats-kafka-bridge/main_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/nats-io/nats.go"
 	"github.com/segmentio/kafka-go"
 
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
@@ -90,6 +91,28 @@ func TestBridgeBatchRecordsMetrics(t *testing.T) {
 	}
 }
 
+func TestRecordNATSConsumerInfoMetrics(t *testing.T) {
+	registry := metrics.NewRegistry()
+	cfg := config{NATSStream: "VEHICLE_INGEST", NATSDurable: "vehicle-kafka-bridge"}
+
+	recordNATSConsumerInfoMetrics(registry, cfg, &nats.ConsumerInfo{
+		NumPending:    17,
+		NumAckPending: 3,
+		NumWaiting:    2,
+	})
+
+	text := registry.Render()
+	for _, want := range []string{
+		`vehicle_bridge_nats_consumer_pending{consumer="vehicle-kafka-bridge",stream="VEHICLE_INGEST"} 17`,
+		`vehicle_bridge_nats_consumer_ack_pending{consumer="vehicle-kafka-bridge",stream="VEHICLE_INGEST"} 3`,
+		`vehicle_bridge_nats_consumer_waiting{consumer="vehicle-kafka-bridge",stream="VEHICLE_INGEST"} 2`,
+	} {
+		if !strings.Contains(text, want) {
+			t.Fatalf("metrics missing %s:\n%s", want, text)
+		}
+	}
+}
+
 type recordingBridgeWriter struct {
 	messages []kafka.Message
 	err      error