test: add unit test for unloading topic before consuming zero queue messages

pulsar/consumer_zero_queue_test.go

@@ -21,9 +21,12 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"log/slog"
+	"os"
 	"testing"
 	"time"
 
+	plog "github.com/apache/pulsar-client-go/pulsar/log"
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/go-connections/nat"
 	"github.com/stretchr/testify/require"
@@ -202,9 +205,9 @@ func TestReconnectConsumer(t *testing.T) {
 	go func() {
 		time.Sleep(3 * time.Second)
 		log.Println("unloading topic")
-		// Simulate a broker restart by stopping the pulsar container
 		topicName, err := utils.GetTopicName(topic)
 		assert.Nil(t, err)
+		// unload topic to trigger consumer reconnect
 		err = admin.Topics().Unload(*topicName)
 		assert.Nil(t, err)
 		log.Println("unloaded topic")
@@ -240,6 +243,91 @@ func TestReconnectConsumer(t *testing.T) {
 	defer c.Terminate(ctx)
 }
 
+func TestUnloadTopicBeforeConsume(t *testing.T) {
+
+	sLogger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelDebug}))
+	client, err := NewClient(ClientOptions{
+		URL:    lookupURL,
+		Logger: plog.NewLoggerWithSlog(sLogger),
+	})
+	assert.Nil(t, err)
+	admin, err := pulsaradmin.NewClient(&config.Config{})
+	assert.Nil(t, err)
+
+	defer client.Close()
+
+	topic := newTopicName()
+	ctx := context.Background()
+	consumer, err := client.Subscribe(ConsumerOptions{
+		Topic:                   topic,
+		SubscriptionName:        "my-sub",
+		EnableZeroQueueConsumer: true,
+	})
+
+	assert.Nil(t, err)
+	_, ok := consumer.(*zeroQueueConsumer)
+	assert.True(t, ok)
+	defer consumer.Close()
+
+	// create producer
+	producer, err := client.CreateProducer(ProducerOptions{
+		Topic:           topic,
+		DisableBatching: false,
+	})
+	assert.Nil(t, err)
+
+	// send 10 messages
+	for i := 0; i < 10; i++ {
+		msg, err := producer.Send(ctx, &ProducerMessage{
+			Payload: []byte(fmt.Sprintf("hello-%d", i)),
+			Key:     "pulsar",
+			Properties: map[string]string{
+				"key-1": "pulsar-1",
+			},
+		})
+		assert.Nil(t, err)
+		log.Printf("send message: %s", msg.String())
+	}
+
+	log.Println("unloading topic")
+	topicName, err := utils.GetTopicName(topic)
+	assert.Nil(t, err)
+	// unload topic to trigger consumer reconnect and send permits
+	err = admin.Topics().Unload(*topicName)
+	assert.Nil(t, err)
+	log.Println("unloaded topic")
+
+	// receive 10 messages
+	for i := 0; i < 10; i++ {
+		msg, err := consumer.Receive(context.Background())
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		expectMsg := fmt.Sprintf("hello-%d", i)
+		expectProperties := map[string]string{
+			"key-1": "pulsar-1",
+		}
+		assert.Equal(t, []byte(expectMsg), msg.Payload())
+		assert.Equal(t, "pulsar", msg.Key())
+		assert.Equal(t, expectProperties, msg.Properties())
+		// ack message
+		err = consumer.Ack(msg)
+		assert.Nil(t, err)
+		log.Printf("receive message: %s", msg.ID().String())
+	}
+	// Make sure there are no more messages
+	timeout, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	_, err = consumer.Receive(timeout)
+	assert.Equal(t, context.DeadlineExceeded, err)
+
+	err = consumer.Unsubscribe()
+	assert.Nil(t, err)
+	consumer.Close()
+	producer.Close()
+}
+
 func TestMultipleConsumer(t *testing.T) {
 	client, err := NewClient(ClientOptions{
 		URL: lookupURL,