diff -r 4ebc2e2fb97c -r 71c04702a3d5 test/langtools/jdk/jshell/MyRemoteExecutionControl.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/jdk/jshell/MyRemoteExecutionControl.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.net.Socket;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Consumer;
+import jdk.jshell.execution.DirectExecutionControl;
+import jdk.jshell.spi.ExecutionControl;
+import jdk.jshell.spi.ExecutionControl.EngineTerminationException;
+import jdk.jshell.spi.ExecutionControl.InternalException;
+import jdk.jshell.spi.ExecutionControl.RunException;
+import static jdk.jshell.execution.Util.forwardExecutionControlAndIO;
+
+/**
+ * A custom remote agent to verify aux channel and custom ExecutionControl.
+ */
+public class MyRemoteExecutionControl extends DirectExecutionControl implements ExecutionControl {
+
+    static PrintStream auxPrint;
+
+    /**
+     * Launch the agent, connecting to the JShell-core over the socket specified
+     * in the command-line argument.
+     *
+     * @param args standard command-line arguments, expectation is the socket
+     * number is the only argument
+     * @throws Exception any unexpected exception
+     */
+    public static void main(String[] args) throws Exception {
+        try {
+            String loopBack = null;
+            Socket socket = new Socket(loopBack, Integer.parseInt(args[0]));
+            InputStream inStream = socket.getInputStream();
+            OutputStream outStream = socket.getOutputStream();
+            Map<String, Consumer<OutputStream>> outputs = new HashMap<>();
+            outputs.put("out", st -> System.setOut(new PrintStream(st, true)));
+            outputs.put("err", st -> System.setErr(new PrintStream(st, true)));
+            outputs.put("aux", st -> { auxPrint = new PrintStream(st, true); });
+            Map<String, Consumer<InputStream>> input = new HashMap<>();
+            input.put("in", st -> System.setIn(st));
+            forwardExecutionControlAndIO(new MyRemoteExecutionControl(), inStream, outStream, outputs, input);
+        } catch (Throwable ex) {
+            throw ex;
+        }
+    }
+
+    @Override
+    public String varValue(String className, String varName)
+            throws RunException, EngineTerminationException, InternalException {
+        auxPrint.print(varName);
+        return super.varValue(className, varName);
+    }
+
+    @Override
+    public Object extensionCommand(String className, Object arg)
+            throws RunException, EngineTerminationException, InternalException {
+        if (!arg.equals("test")) {
+            throw new InternalException("expected extensionCommand arg to be 'test' got: " + arg);
+        }
+        return "ribbit";
+    }
+
+}