org.deventropy.shared.utils.ClassUtilTest.java Source code

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Here is the source code for org.deventropy.shared.utils.ClassUtilTest.java

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/* 
 * Copyright 2016 Development Entropy (deventropy.org) Contributors
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *  http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.deventropy.shared.utils;

import static org.junit.Assert.assertEquals;

import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;

import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;

import org.apache.commons.io.FileUtils;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;

/**
 * @author Bindul Bhowmik
 *
 */
public class ClassUtilTest {

    @Rule
    public TemporaryFolder workingFolder = new TemporaryFolder();

    /**
     * Test method for {@link org.deventropy.shared.utils.ClassUtil#getApplicableClassloader(java.lang.Object)}.
     * @throws InterruptedException Error running worker
     */
    @Test
    public void testGetApplicableClassloaderNullContextClassLoader() throws InterruptedException {

        final ContextClNullingObject testObj = new ContextClNullingObject(null);
        final Thread worker = new Thread(testObj);
        worker.start();
        worker.join();

        assertEquals(ClassUtil.class.getClassLoader(), testObj.getReturnedCl());
    }

    /**
     * Test method for {@link org.deventropy.shared.utils.ClassUtil#getApplicableClassloader(java.lang.Object)}.
     * @throws InterruptedException Error running worker
     */
    @Test
    public void testGetApplicableClassloaderSecurityException() throws InterruptedException {

        final ClassLoaderGetterRunnable testRunner = new ClassLoaderGetterRunnable(null);
        final NoContextClassLoaderThread worker = new NoContextClassLoaderThread(testRunner);
        //      final Thread worker = new Thread(testRunner);
        worker.start();
        worker.join();

        assertEquals(ClassUtil.class.getClassLoader(), testRunner.getReturnedCl());
    }

    @Test
    public void testCallerClassloader() throws Exception {

        // Write the source file - see
        // http://stackoverflow.com/questions/2946338/how-do-i-programmatically-compile-and-instantiate-a-java-class
        final File sourceFolder = workingFolder.newFolder();
        // Prepare source somehow.
        final String source = "package test; public class Test { }";
        // Save source in .java file.
        final File sourceFile = new File(sourceFolder, "test/Test.java");
        sourceFile.getParentFile().mkdirs();
        FileUtils.writeStringToFile(sourceFile, source, "UTF-8");

        // Compile the file
        final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        final StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
        final Iterable<? extends JavaFileObject> compilationUnit = fileManager
                .getJavaFileObjectsFromFiles(Arrays.asList(sourceFile));
        compiler.getTask(null, fileManager, null, null, null, compilationUnit).call();

        // Create the class loader
        final URLClassLoader urlcl = new URLClassLoader(new URL[] { sourceFolder.toURI().toURL() });
        final Class<?> loadedClass = urlcl.loadClass("test.Test");

        final ContextClNullingObject testObj = new ContextClNullingObject(loadedClass.newInstance());
        final Thread worker = new Thread(testObj);
        worker.start();
        worker.join();

        assertEquals(urlcl, testObj.getReturnedCl());

        urlcl.close();
    }

    /**
     * Worker runnable
     * 
     * @author Bindul Bhowmik
     */
    private class ClassLoaderGetterRunnable implements Runnable {
        private ClassLoader returnedCl;
        private Object callingObj;

        protected ClassLoaderGetterRunnable(final Object callingObj) {
            this.callingObj = callingObj;
        }

        @Override
        public void run() {
            returnedCl = ClassUtil.getApplicableClassloader(callingObj);
        }

        public ClassLoader getReturnedCl() {
            return returnedCl;
        }
    }

    /**
     * Worker object.
     * 
     * @author Bindul Bhowmik
     */
    private final class ContextClNullingObject extends ClassLoaderGetterRunnable {

        private ContextClNullingObject(final Object callingObj) {
            super(callingObj);
        }

        @Override
        public void run() {
            final Thread currentThread = Thread.currentThread();
            final ClassLoader savedCl = currentThread.getContextClassLoader();

            currentThread.setContextClassLoader(null);
            super.run();

            if (null != savedCl) {
                currentThread.setContextClassLoader(savedCl);
            }
        }
    }

    /**
     * Thread that denies access to the context class loader
     * @author Bindul Bhowmik
     */
    private final class NoContextClassLoaderThread extends Thread {

        NoContextClassLoaderThread(final Runnable target) {
            super(target);
        }

        @Override
        public ClassLoader getContextClassLoader() {
            final StackTraceElement[] stackTraces = getStackTrace();
            if ("org.deventropy.shared.utils.ClassUtil".equals(stackTraces[2].getClassName())
                    && "getApplicableClassloader".equals(stackTraces[2].getMethodName())) {
                // Log4J (among others) also calls this method, and if a security exception is thrown the tests fail;
                // so fail the test only when called from the test method
                throw new SecurityException();
            }
            return super.getContextClassLoader();
        }
    }
}