PreferencesTestCase.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.test.uitools;

import java.util.List;
import java.util.prefs.AbstractPreferences;
import java.util.prefs.Preferences;

import junit.framework.TestCase;

import org.eclipse.persistence.tools.workbench.test.utility.TestTools;
import org.eclipse.persistence.tools.workbench.utility.ClassTools;


/**
 * set up and tear down a test node for any subclass that
 * needs to test preferences-related stuff
 */
public abstract class PreferencesTestCase extends TestCase {
    protected Preferences classNode;
    public Preferences testNode;
    protected static final String TEST_NODE_NAME = "test node";

    public PreferencesTestCase(String name) {
        super(name);
    }

    protected void setUp() throws Exception {
        super.setUp();
        Preferences packageNode = Preferences.userNodeForPackage(this.getClass());
        this.classNode = packageNode.node(ClassTools.shortClassNameForObject(this));
        // clean out any leftover junk...
        if ((this.classNode.keys().length > 0) || (this.classNode.childrenNames().length > 0)) {
            this.classNode.removeNode();
            // ...and re-create the node
            this.classNode = packageNode.node(ClassTools.shortClassNameForObject(this));
        }
        this.testNode = this.classNode.node(TEST_NODE_NAME);
    }

    protected void tearDown() throws Exception {
        // wait for all the events to be delivered before tearing down
        this.waitForEventQueueToClear();
        Preferences node = this.classNode.parent();
        this.classNode.removeNode();
        while (this.nodeIsVestigial(node)) {
            Preferences parent = node.parent();
            node.removeNode();
            node = parent;
        }
        TestTools.clear(this);
        super.tearDown();
    }

    private boolean nodeIsVestigial(Preferences node) throws Exception {
        return (node != null)
            && (node.keys().length == 0)
            && (node.childrenNames().length == 0)
            && (node != Preferences.userRoot());
    }

    protected void waitForEventQueueToClear() {
        try {
            while ( ! this.preferencesEventQueue().isEmpty()) {
                Thread.sleep(100);
            }
            Thread.sleep(100);
        } catch (InterruptedException ex) {
            throw new RuntimeException(ex);
        }
    }

    private List preferencesEventQueue() {
        return (List) ClassTools.getStaticFieldValue(AbstractPreferences.class, "eventQueue");
    }

}