Enable ServerLowLevel tests not running and add PUB QoS1 test (#580)

- Add unit test to check a second publish is sent if the not PUBACK is received in `FLIGHT_BEFORE_RESEND_MS` interval.
- Fixed ServerLowLevel tests not running.

* Added a test for #573

broker/src/main/java/io/moquette/BrokerConstants.java

@@ -82,6 +82,9 @@ public final class BrokerConstants {
 
     public static final String STORAGE_CLASS_NAME = "storage_class";
 
+    public static final int FLIGHT_BEFORE_RESEND_MS = 5_000;
+    public static final int INFLIGHT_WINDOW_SIZE = 10;
+
     private BrokerConstants() {
     }
 }

broker/src/main/java/io/moquette/broker/Session.java

@@ -15,6 +15,8 @@
  */
 package io.moquette.broker;
 
+import static io.moquette.BrokerConstants.FLIGHT_BEFORE_RESEND_MS;
+import static io.moquette.BrokerConstants.INFLIGHT_WINDOW_SIZE;
 import io.moquette.broker.subscriptions.Subscription;
 import io.moquette.broker.subscriptions.Topic;
 import io.netty.buffer.ByteBuf;
@@ -34,8 +36,6 @@
 class Session {
 
     private static final Logger LOG = LoggerFactory.getLogger(Session.class);
-    private static final int FLIGHT_BEFORE_RESEND_MS = 5_000;
-    private static final int INFLIGHT_WINDOW_SIZE = 10;
 
     static class InFlightPacket implements Delayed {
 

broker/src/test/java/io/moquette/integration/ServerLowlevelMessagesIntegrationTests.java → broker/src/test/java/io/moquette/integration/ServerLowlevelMessagesIntegrationTest.java

@@ -16,6 +16,7 @@
 
 package io.moquette.integration;
 
+import static io.moquette.BrokerConstants.FLIGHT_BEFORE_RESEND_MS;
 import io.moquette.broker.Server;
 import io.moquette.broker.config.IConfig;
 import io.moquette.broker.config.MemoryConfig;
@@ -38,11 +39,12 @@
 import java.util.concurrent.TimeUnit;
 import static io.netty.handler.codec.mqtt.MqttConnectReturnCode.*;
 import static java.nio.charset.StandardCharsets.UTF_8;
+import java.util.concurrent.atomic.AtomicBoolean;
 import static org.junit.jupiter.api.Assertions.*;
 
-public class ServerLowlevelMessagesIntegrationTests {
+public class ServerLowlevelMessagesIntegrationTest {
 
-    private static final Logger LOG = LoggerFactory.getLogger(ServerLowlevelMessagesIntegrationTests.class);
+    private static final Logger LOG = LoggerFactory.getLogger(ServerLowlevelMessagesIntegrationTest.class);
     static MqttClientPersistence s_dataStore;
     Server m_server;
     Client m_client;
@@ -171,4 +173,43 @@ public void testWillMessageIsPublishedOnClientBadDisconnection() throws Interrup
         m_willSubscriber.disconnect();
     }
 
+    @Test
+    public void testResendNotAckedPublishes() throws MqttException, InterruptedException {
+        LOG.info("*** testResendNotAckedPublishes ***");
+        String topic = "/test";
+
+        MqttClient subscriber = new MqttClient("tcp://localhost:1883", "Subscriber");
+        MqttClient publisher = new MqttClient("tcp://localhost:1883", "Publisher");
+
+        try {
+            subscriber.connect();
+            publisher.connect();
+
+            AtomicBoolean isFirst = new AtomicBoolean(true);
+            AtomicBoolean receivedPublish = new AtomicBoolean(false);
+            subscriber.subscribe(topic, 1, (String topic1, org.eclipse.paho.client.mqttv3.MqttMessage message) -> {
+                if (isFirst.getAndSet(false)) {
+                    // wait to trigger resending PUBLISH
+                    TimeUnit.SECONDS.sleep(FLIGHT_BEFORE_RESEND_MS * 2);
+                } else {
+                    receivedPublish.set(true);
+                }
+            });
+
+            publisher.publish(topic, "hello".getBytes(), 1, false);
+            Awaitility.await("Waiting for resend.")
+                .atMost(FLIGHT_BEFORE_RESEND_MS * 3, TimeUnit.MILLISECONDS)
+                .pollDelay(FLIGHT_BEFORE_RESEND_MS * 2, TimeUnit.MILLISECONDS)
+                .pollInterval(100, TimeUnit.MILLISECONDS)
+                .untilTrue(receivedPublish);
+        } finally {
+            try {
+                if (subscriber.isConnected()) {
+                    subscriber.disconnect();
+                }
+            } finally {
+                publisher.disconnect();
+            }
+        }
+    }
 }