Stabilize test by keeping reference to NetClient

Closes #5853

Author: ahus1

vertx-core/src/test/java/io/vertx/tests/http/HttpTest.java

@@ -11,6 +11,7 @@
 
 package io.vertx.tests.http;
 
+import io.netty.buffer.ByteBufUtil;
 import io.netty.channel.ConnectTimeoutException;
 import io.netty.channel.EventLoop;
 import io.netty.handler.codec.compression.DecompressionException;
@@ -4779,14 +4780,16 @@ protected void testHttpConnect(RequestOptions options, int sc) {
     Buffer buffer = TestUtils.randomBuffer(128);
     Buffer received = Buffer.buffer();
     CompletableFuture<Void> closeSocket = new CompletableFuture<>();
-    vertx.createNetServer(new NetServerOptions().setPort(1235).setHost("localhost")).connectHandler(socket -> {
+    vertx.createNetServer(new NetServerOptions().setPort(0).setHost("localhost")).connectHandler(socket -> {
       socket.handler(socket::write);
       closeSocket.thenAccept(v -> {
         socket.close();
       });
     }).listen().onComplete(onSuccess(netServer -> {
+      // Declare netClient here to avoid having it randomly garbage collected just after it created the connection
+      NetClient netClient = vertx.createNetClient(new NetClientOptions());
       server.requestHandler(req -> {
-        vertx.createNetClient(new NetClientOptions()).connect(1235, "localhost").onComplete(onSuccess(dst -> {
+        netClient.connect(netServer.actualPort(), "localhost").onComplete(onSuccess(dst -> {
 
           req.response().setStatusCode(sc);
           req.response().setStatusMessage("Connection established");
@@ -4812,7 +4815,7 @@ protected void testHttpConnect(RequestOptions options, int sc) {
                 }
               });
               socket.closeHandler(v -> {
-                assertEquals(buffer, received);
+                assertEquals(ByteBufUtil.hexDump(buffer.getBytes()),ByteBufUtil.hexDump(received.getBytes()));
                 testComplete();
               });
               socket.write(buffer);