dcevm/dcevm/src/test/java7/com/github/dcevm/test/util/HotSwapTestHelper.java

/*
 * Copyright (c) 2010, 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.
 *
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package com.github.dcevm.test.util;

import com.github.dcevm.HotSwapTool;

/**
 * Shortcut methods for testing. Methods are named this way to make them more visible in the test code.
 * @author Ivan Dubrov
 */
public class HotSwapTestHelper {
    /**
     * Returns the current version of the inner classes of an outer class.
     * <p/>
     * Caller class is used as an outer class.
     *
     * @return the version of the inner classes of the outer class
     */
    public static int __version__() {
        return HotSwapTool.getCurrentVersion(determineOuter(0));
    }

    /**
     * Redefines all inner classes of a outer class to a specified version. Inner classes who do not have a particular
     * representation for a version remain unchanged.
     * <p/>
     * Caller class is used as an outer class.
     *
     * @param versionNumber the target version number
     */
    public static void __toVersion__(int versionNumber) {
        HotSwapTool.toVersion(determineOuter(0), versionNumber);
    }

    /**
     * Helper method to determine caller outer class.
     * <p/>
     * Takes caller class and finds its top enclosing class (which is supposed to be test class).
     *
     * @param level on which level this call is being made. 0 - call is made immediately in the method of HotSwapTool.
     * @return outer class reference
     */
    private static Class<?> determineOuter(int level) {
        StackTraceElement[] stack = Thread.currentThread().getStackTrace();
        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        // one for Thread#getStackTrace
        // one for #determineOuter
        // one for the caller
        String callerName = stack[level + 3].getClassName();
        try {
            Class<?> clazz = cl.loadClass(callerName);
            while (clazz.getEnclosingClass() != null) {
                clazz = clazz.getEnclosingClass();
            }
            return clazz;
        } catch (ClassNotFoundException e) {
            throw new IllegalArgumentException("Cannot find caller class: " + callerName, e);
        }
    }
}