Added unit test for connection release

Author: lutovich

driver/src/test/java/org/neo4j/driver/internal/async/NettyConnectionTest.java

@@ -28,6 +28,7 @@
 import org.junit.Test;
 
 import java.util.Set;
+import java.util.concurrent.CompletionStage;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
@@ -227,6 +228,30 @@ public void shouldReturnServerVersionWhenReleased()
         assertEquals( version, connection.serverVersion() );
     }
 
+    @Test
+    public void shouldReturnSameCompletionStageFromRelease()
+    {
+        EmbeddedChannel channel = new EmbeddedChannel();
+        InboundMessageDispatcher messageDispatcher = new InboundMessageDispatcher( channel, DEV_NULL_LOGGING );
+        ChannelAttributes.setMessageDispatcher( channel, messageDispatcher );
+
+        NettyConnection connection = newConnection( channel );
+
+        CompletionStage<Void> releaseStage1 = connection.release();
+        CompletionStage<Void> releaseStage2 = connection.release();
+        CompletionStage<Void> releaseStage3 = connection.release();
+
+        channel.runPendingTasks();
+
+        // RESET should be send only once
+        assertEquals( 1, channel.outboundMessages().size() );
+        assertEquals( RESET, channel.outboundMessages().poll() );
+
+        // all returned stages should be the same
+        assertEquals( releaseStage1, releaseStage2 );
+        assertEquals( releaseStage2, releaseStage3 );
+    }
+
     private void testWriteInEventLoop( String threadName, Consumer<NettyConnection> action ) throws Exception
     {
         EmbeddedChannel channel = spy( new EmbeddedChannel() );

driver/src/test/java/org/neo4j/driver/v1/util/TestUtil.java

@@ -52,6 +52,12 @@ private TestUtil()
     {
     }
 
+    @SafeVarargs
+    public static <T> List<T> awaitAll( CompletionStage<T>... stages )
+    {
+        return awaitAll( Arrays.asList( stages ) );
+    }
+
     public static <T> List<T> awaitAll( List<CompletionStage<T>> stages )
     {
         List<T> result = new ArrayList<>();