Refactor MemoryAlarms test

It is now more explicit about what it does. Cleaned up also some dead
code.

(cherry picked from commit e388ec1)

Author: acogoluegnes

src/test/java/com/rabbitmq/client/test/server/MemoryAlarms.java

@@ -19,14 +19,13 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 
 import java.io.IOException;
+import java.time.Duration;
 import java.util.concurrent.TimeoutException;
 
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import com.rabbitmq.client.Channel;
-import com.rabbitmq.client.Connection;
 import com.rabbitmq.client.QueueingConsumer;
 import com.rabbitmq.client.test.BrokerTestCase;
 import org.junit.jupiter.api.TestInfo;
@@ -35,34 +34,22 @@ public class MemoryAlarms extends BrokerTestCase {
 
     private static final String Q = "Restart";
 
-    private Connection connection2;
-    private Channel channel2;
+    private static final Duration HEARTBEAT = Duration.ofSeconds(1);
+    // Must exceed 2x heartbeat to also verify the connection survives the heartbeat timeout
+    private static final long DELIVERY_TIMEOUT_MS = HEARTBEAT.multipliedBy(3).plusMillis(100).toMillis();
 
     @BeforeEach
     @Override
     public void setUp(TestInfo info) throws IOException, TimeoutException {
-        connectionFactory.setRequestedHeartbeat(1);
+        connectionFactory.setRequestedHeartbeat((int) HEARTBEAT.getSeconds());
         super.setUp(info);
-        if (connection2 == null) {
-            connection2 = connectionFactory.newConnection();
-        }
-        channel2 = connection2.createChannel();
     }
 
     @AfterEach
     @Override
     public void tearDown(TestInfo info) throws IOException, TimeoutException {
         clearAllResourceAlarms();
-        if (channel2 != null) {
-            channel2.abort();
-            channel2 = null;
-        }
-        if (connection2 != null) {
-            connection2.abort(10_000);
-            connection2 = null;
-        }
         super.tearDown(info);
-        connectionFactory.setRequestedHeartbeat(0);
     }
 
     @Override
@@ -85,19 +72,18 @@ protected void releaseResources() throws IOException {
         String consumerTag = channel.basicConsume(Q, true, c);
         // publishes after an alarm should not go through
         basicPublishVolatile(Q);
-        // the publish is async, so this is racy. This also tests we don't die
-        // by heartbeat (3x heartbeat interval + epsilon)
-        assertNull(c.nextDelivery(3100));
+        // the publish is async, so this is racy.
+        // This also tests we don't die by heartbeat
+        assertNull(c.nextDelivery(DELIVERY_TIMEOUT_MS));
         // once the alarm has cleared the publishes should go through
         clearResourceAlarm("memory");
-        assertNotNull(c.nextDelivery(3100));
+        assertNotNull(c.nextDelivery(DELIVERY_TIMEOUT_MS));
         // everything should be back to normal
         channel.basicCancel(consumerTag);
         basicPublishVolatile(Q);
         assertNotNull(basicGet(Q));
     }
 
-
     @Test public void overlappingAlarmsFlowControl() throws IOException, InterruptedException {
         QueueingConsumer c = new QueueingConsumer(channel);
         String consumerTag = channel.basicConsume(Q, true, c);
@@ -111,12 +97,11 @@ protected void releaseResources() throws IOException {
         clearResourceAlarm("memory");
         assertNull(c.nextDelivery(100));
         clearResourceAlarm("disk");
-        assertNotNull(c.nextDelivery(3100));
+        assertNotNull(c.nextDelivery(DELIVERY_TIMEOUT_MS));
 
         channel.basicCancel(consumerTag);
         basicPublishVolatile(Q);
         assertNotNull(basicGet(Q));
     }
 
-
 }