SeparateClassloaderRunner.java

package io.sqreen.powerwaf.test;

import org.junit.runner.notification.RunNotifier;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.InitializationError;
import org.junit.runners.model.Statement;
import org.junit.runners.model.TestClass;

import java.lang.reflect.UndeclaredThrowableException;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Loads the test in a separate classloader. The URLs of the classloader
 * for non-delegated classes are those of the source and test classes.
 */
public class SeparateClassloaderRunner extends BlockJUnit4ClassRunner  {

    public SeparateClassloaderRunner(Class<?> klass) throws InitializationError {
        super(klass);
    }

    @Override
    protected TestClass createTestClass(Class<?> testClass) {
        return super.createTestClass(replaceClass(testClass));
    }

    private ChildFirstURLClassLoader cl;
    private Class<?> replaceClass(Class<?> klass) {
        ClassLoader parentCl = klass.getClassLoader();

        String urlSrc = parentCl.getResource("io/sqreen/powerwaf/Powerwaf.class").getFile();
        int endOfDirSrc = urlSrc.indexOf("io/sqreen/");
        String srcClassesDir = urlSrc.substring(0, endOfDirSrc);

        String urlTest = parentCl.getResource("io/sqreen/powerwaf/test/SeparateClassloaderRunner.class").getFile();
        int endOfDirTest = urlTest.indexOf("io/sqreen/");
        String testClassesDir = urlTest.substring(0, endOfDirTest);

        ChildFirstURLClassLoader cl;
        try {
            cl = new ChildFirstURLClassLoader(
                    new URL[] {
                            new URL("file://" + srcClassesDir),
                            new URL("file://" + testClassesDir),
                    }, parentCl);
        } catch (MalformedURLException e) {
            throw new UndeclaredThrowableException(e);
        }

        String klassName = klass.getName();

        try {
            return cl.loadClass(klassName, false, false);
        } catch (Exception e) {
            throw new UndeclaredThrowableException(e);
        }
    }


    @Override
    protected Statement classBlock(RunNotifier notifier) {
        final Statement superStatement = super.classBlock(notifier);
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                superStatement.evaluate();
                System.gc();
            }
        };
    }
}