diff -r ae352b763959 -r d382dacfd73f rt/vm/src/test/java/org/apidesign/vm4brwsr/TestVM.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rt/vm/src/test/java/org/apidesign/vm4brwsr/TestVM.java	Tue Feb 26 16:54:16 2013 +0100
@@ -0,0 +1,170 @@
+/**
+ * Back 2 Browser Bytecode Translator
+ * Copyright (C) 2012 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.vm4brwsr;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.Enumeration;
+import javax.script.Invocable;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+import static org.testng.Assert.*;
+
+final class TestVM {
+    private final Invocable code;
+    private final CharSequence codeSeq;
+    private final Object bck2brwsr;
+    
+    
+    private TestVM(Invocable code, CharSequence codeSeq) throws ScriptException, NoSuchMethodException {
+        this.code = code;
+        this.codeSeq = codeSeq;
+        this.bck2brwsr = code.invokeFunction("bck2brwsr");
+    }
+    
+
+    public Object execCode(
+        String msg, Class<?> clazz, String method, 
+        Object expRes, Object... args
+    ) throws Exception {
+        Object ret = null;
+        try {
+            ret = code.invokeMethod(bck2brwsr, "loadClass", clazz.getName());
+            ret = code.invokeMethod(ret, method, args);
+        } catch (ScriptException ex) {
+            fail("Execution failed in " + dumpJS(codeSeq), ex);
+        } catch (NoSuchMethodException ex) {
+            fail("Cannot find method in " + dumpJS(codeSeq), ex);
+        }
+        if (ret == null && expRes == null) {
+            return null;
+        }
+        if (expRes != null && expRes.equals(ret)) {
+            return null;
+        }
+        if (expRes instanceof Number) {
+            // in case of Long it is necessary convert it to number
+            // since the Long is represented by two numbers in JavaScript
+            try {
+                ret = code.invokeMethod(ret, "toFP");
+                ret = code.invokeFunction("Number", ret);
+            } catch (ScriptException ex) {
+                fail("Conversion to number failed in " + dumpJS(codeSeq), ex);
+            } catch (NoSuchMethodException ex) {
+                fail("Cannot find global Number(x) function in " + dumpJS(codeSeq), ex);
+            }
+        }
+        return ret;
+    }
+    
+    void assertExec(
+        String msg, Class clazz, String method, Object expRes, Object... args
+    ) throws Exception {
+        Object ret = execCode(msg, clazz, method, expRes, args);
+        if (ret == null) {
+            return;
+        }
+        if (expRes != null && expRes.equals(ret)) {
+            return;
+        }
+        assertEquals(ret, expRes, msg + "was: " + ret + "\n" + dumpJS(codeSeq));
+    }    
+
+    static TestVM compileClass(String... names) throws ScriptException, IOException {
+        return compileClass(null, names);
+    }
+    
+    static TestVM compileClass(StringBuilder sb, String... names) throws ScriptException, IOException {
+        return compileClass(sb, null, names);
+    }
+
+    static TestVM compileClass(StringBuilder sb, ScriptEngine[] eng, String... names) throws ScriptException, IOException {
+        if (sb == null) {
+            sb = new StringBuilder();
+        }
+        Bck2Brwsr.generate(sb, new EmulationResources(), names);
+        ScriptEngineManager sem = new ScriptEngineManager();
+        ScriptEngine js = sem.getEngineByExtension("js");
+        if (eng != null) {
+            eng[0] = js;
+        }
+        try {
+            Object res = js.eval(sb.toString());
+            assertTrue(js instanceof Invocable, "It is invocable object: " + res);
+            return new TestVM((Invocable) js, sb);
+        } catch (Exception ex) {
+            if (sb.length() > 2000) {
+                sb = dumpJS(sb);
+            }
+            fail("Could not evaluate:\n" + sb, ex);
+            return null;
+        }
+    }
+
+    Object loadClass(String loadClass, String name) throws ScriptException, NoSuchMethodException {
+        return code.invokeMethod(bck2brwsr, "loadClass", Exceptions.class.getName());
+    }
+    
+    Object invokeMethod(Object obj, String method, Object... params) throws ScriptException, NoSuchMethodException {
+        return code.invokeMethod(obj, method, params);
+    }
+
+    Object invokeFunction(String methodName, Object... args) throws ScriptException, NoSuchMethodException {
+        return code.invokeFunction(methodName, args);
+    }
+
+    static StringBuilder dumpJS(CharSequence sb) throws IOException {
+        File f = File.createTempFile("execution", ".js");
+        FileWriter w = new FileWriter(f);
+        w.append(sb);
+        w.close();
+        return new StringBuilder(f.getPath());
+    }
+
+    @Override
+    public String toString() {
+        try {
+            return dumpJS(codeSeq).toString();
+        } catch (IOException ex) {
+            return ex.toString();
+        }
+    }
+    
+    
+    private static class EmulationResources implements Bck2Brwsr.Resources {
+        @Override
+        public InputStream get(String name) throws IOException {
+            Enumeration<URL> en = StaticMethodTest.class.getClassLoader().getResources(name);
+            URL u = null;
+            while (en.hasMoreElements()) {
+                u = en.nextElement();
+            }
+            if (u == null) {
+                throw new IOException("Can't find " + name);
+            }
+            if (u.toExternalForm().contains("rt.jar!")) {
+                throw new IOException("No emulation for " + u);
+            }
+            return u.openStream();
+        }
+    }
+}