diff -r 000000000000 -r 621825e167d7 ko/kosample/js/src/test/java/org/apidesign/bck2brwsr/kosample/js/JsInteractionTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ko/kosample/js/src/test/java/org/apidesign/bck2brwsr/kosample/js/JsInteractionTest.java	Tue Apr 26 08:04:12 2016 +0200
@@ -0,0 +1,57 @@
+/**
+ * Back 2 Browser Bytecode Translator
+ * Copyright (C) 2012-2015 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. Look for COPYING file in the top folder.
+ * If not, see http://opensource.org/licenses/GPL-2.0.
+ */
+package org.apidesign.bck2brwsr.kosample.js;
+
+import java.io.Closeable;
+import net.java.html.boot.script.Scripts;
+import org.netbeans.html.boot.spi.Fn;
+import static org.testng.Assert.assertEquals;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+/** Tests for behavior of @JavaScriptBody methods. Set your JavaScript 
+ * environment up (for example define <code>alert</code> or use some
+ * emulation library like <em>env.js</em>), register script presenter 
+ * and then you can call methods that deal with JavaScript in your tests.
+ */
+public class JsInteractionTest {
+    private Closeable jsEngine;
+    @BeforeMethod public void initializeJSEngine() throws Exception {
+        jsEngine = Fn.activate(Scripts.createPresenter());
+    }
+    
+    @AfterMethod public void shutdownJSEngine() throws Exception {
+        jsEngine.close();
+    }
+    @Test public void testCallbackFromJavaScript() throws Exception {
+        class R implements Runnable {
+            int called;
+
+            @Override
+            public void run() {
+                called++;
+            }
+        }
+        R callback = new R();
+        
+        Dialogs.confirmByUser("Hello", callback);
+        
+        assertEquals(callback.called, 1, "One immediate callback");
+    }
+}