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Commons Collections example source code file (AbstractTestObject.java)

This example Commons Collections source code file (AbstractTestObject.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Collections tags/keywords

bytearrayoutputstream, bytearrayoutputstream, classnotfoundexception, io, ioexception, ioexception, object, object, objectinputstream, objectoutputstream, serializable, string, string, stringbuffer, when

The Commons Collections AbstractTestObject.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.commons.collections;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;

/**
 * Abstract test class for {@link java.lang.Object} methods and contracts.
 * <p>
 * To use, simply extend this class, and implement
 * the {@link #makeObject()} method.
 * <p>
 * If your {@link Object} fails one of these tests by design,
 * you may still use this base set of cases.  Simply override the
 * test case (method) your {@link Object} fails.
 *
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Rodney Waldhoff
 * @author Stephen Colebourne
 * @author Anonymous
 */
public abstract class AbstractTestObject extends BulkTest {

    /** Current major release for Collections */
    public static final int COLLECTIONS_MAJOR_VERSION = 3;
    
    /**
     * JUnit constructor.
     * 
     * @param testName  the test class name
     */
    public AbstractTestObject(String testName) {
        super(testName);
    }

    //-----------------------------------------------------------------------
    /**
     * Implement this method to return the object to test.
     * 
     * @return the object to test
     */
    public abstract Object makeObject();

    /**
     * Override this method if a subclass is testing an object
     * that cannot serialize an "empty" Collection.
     * (e.g. Comparators have no contents)
     * 
     * @return true
     */
    public boolean supportsEmptyCollections() {
        return true;
    }

    /**
     * Override this method if a subclass is testing an object
     * that cannot serialize a "full" Collection.
     * (e.g. Comparators have no contents)
     * 
     * @return true
     */
    public boolean supportsFullCollections() {
        return true;
    }

    /**
     * Is serialization testing supported.
     * Default is true.
     */
    public boolean isTestSerialization() {
        return true;
    }

    /**
     * Returns true to indicate that the collection supports equals() comparisons.
     * This implementation returns true;
     */
    public boolean isEqualsCheckable() {
        return true;
    }

    //-----------------------------------------------------------------------
    public void testObjectEqualsSelf() {
        Object obj = makeObject();
        assertEquals("A Object should equal itself", obj, obj);
    }

    public void testEqualsNull() {
        Object obj = makeObject();
        assertEquals(false, obj.equals(null)); // make sure this doesn't throw NPE either
    }

    public void testObjectHashCodeEqualsSelfHashCode() {
        Object obj = makeObject();
        assertEquals("hashCode should be repeatable", obj.hashCode(), obj.hashCode());
    }

    public void testObjectHashCodeEqualsContract() {
        Object obj1 = makeObject();
        if (obj1.equals(obj1)) {
            assertEquals(
                "[1] When two objects are equal, their hashCodes should be also.",
                obj1.hashCode(), obj1.hashCode());
        }
        Object obj2 = makeObject();
        if (obj1.equals(obj2)) {
            assertEquals(
                "[2] When two objects are equal, their hashCodes should be also.",
                obj1.hashCode(), obj2.hashCode());
            assertTrue(
                "When obj1.equals(obj2) is true, then obj2.equals(obj1) should also be true",
                obj2.equals(obj1));
        }
    }

    public void testSerializeDeserializeThenCompare() throws Exception {
        Object obj = makeObject();
        if (obj instanceof Serializable && isTestSerialization()) {
            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
            ObjectOutputStream out = new ObjectOutputStream(buffer);
            out.writeObject(obj);
            out.close();

            ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray()));
            Object dest = in.readObject();
            in.close();
            if (isEqualsCheckable()) {
                assertEquals("obj != deserialize(serialize(obj))", obj, dest);
            }
        }
    }

    /**
     * Sanity check method, makes sure that any Serializable
     * class can be serialized and de-serialized in memory, 
     * using the handy makeObject() method
     * 
     * @throws IOException
     * @throws ClassNotFoundException
     */
    public void testSimpleSerialization() throws Exception {
        Object o = makeObject();
        if (o instanceof Serializable && isTestSerialization()) {
            byte[] objekt = writeExternalFormToBytes((Serializable) o);
            Object p = readExternalFormFromBytes(objekt);
        }
    }

    /**
     * Tests serialization by comparing against a previously stored version in CVS.
     * If the test object is serializable, confirm that a canonical form exists.
     */
    public void testCanonicalEmptyCollectionExists() {
        if (supportsEmptyCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
            Object object = makeObject();
            if (object instanceof Serializable) {
                String name = getCanonicalEmptyCollectionName(object);
                assertTrue(
                    "Canonical empty collection (" + name + ") is not in CVS",
                    new File(name).exists());
            }
        }
    }

    /**
     * Tests serialization by comparing against a previously stored version in CVS.
     * If the test object is serializable, confirm that a canonical form exists.
     */
    public void testCanonicalFullCollectionExists() {
        if (supportsFullCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
            Object object = makeObject();
            if (object instanceof Serializable) {
                String name = getCanonicalFullCollectionName(object);
                assertTrue(
                    "Canonical full collection (" + name + ") is not in CVS",
                    new File(name).exists());
            }
        }
    }

    // protected implementation
    //-----------------------------------------------------------------------
    /**
     * Get the version of Collections that this object tries to
     * maintain serialization compatibility with. Defaults to 1, the
     * earliest Collections version. (Note: some collections did not
     * even exist in this version).
     * 
     * This constant makes it possible for TestMap (and other subclasses,
     * if necessary) to automatically check CVS for a versionX copy of a
     * Serialized object, so we can make sure that compatibility is maintained.
     * See, for example, TestMap.getCanonicalFullMapName(Map map).
     * Subclasses can override this variable, indicating compatibility
     * with earlier Collections versions.
     * 
     * @return The version, or <code>null if this object shouldn't be
     * tested for compatibility with previous versions.
     */
    public String getCompatibilityVersion() {
        return "1";
    }

    protected String getCanonicalEmptyCollectionName(Object object) {
        StringBuffer retval = new StringBuffer();
        retval.append("data/test/");
        String colName = object.getClass().getName();
        colName = colName.substring(colName.lastIndexOf(".") + 1, colName.length());
        retval.append(colName);
        retval.append(".emptyCollection.version");
        retval.append(getCompatibilityVersion());
        retval.append(".obj");
        return retval.toString();
    }

    protected String getCanonicalFullCollectionName(Object object) {
        StringBuffer retval = new StringBuffer();
        retval.append("data/test/");
        String colName = object.getClass().getName();
        colName = colName.substring(colName.lastIndexOf(".") + 1, colName.length());
        retval.append(colName);
        retval.append(".fullCollection.version");
        retval.append(getCompatibilityVersion());
        retval.append(".obj");
        return retval.toString();
    }

    /**
     * Write a Serializable or Externalizable object as
     * a file at the given path.  NOT USEFUL as part
     * of a unit test; this is just a utility method
     * for creating disk-based objects in CVS that can become
     * the basis for compatibility tests using
     * readExternalFormFromDisk(String path)
     * 
     * @param o Object to serialize
     * @param path path to write the serialized Object
     * @exception IOException
     */
    protected void writeExternalFormToDisk(Serializable o, String path) throws IOException {
        FileOutputStream fileStream = new FileOutputStream(path);
        writeExternalFormToStream(o, fileStream);
    }

    /**
     * Converts a Serializable or Externalizable object to
     * bytes.  Useful for in-memory tests of serialization
     * 
     * @param o Object to convert to bytes
     * @return serialized form of the Object
     * @exception IOException
     */
    protected byte[] writeExternalFormToBytes(Serializable o) throws IOException {
        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
        writeExternalFormToStream(o, byteStream);
        return byteStream.toByteArray();
    }

    /**
     * Reads a Serialized or Externalized Object from disk.
     * Useful for creating compatibility tests between
     * different CVS versions of the same class
     * 
     * @param path path to the serialized Object
     * @return the Object at the given path
     * @exception IOException
     * @exception ClassNotFoundException
     */
    protected Object readExternalFormFromDisk(String path) throws IOException, ClassNotFoundException {
        FileInputStream stream = new FileInputStream(path);
        return readExternalFormFromStream(stream);
    }

    /**
     * Read a Serialized or Externalized Object from bytes.
     * Useful for verifying serialization in memory.
     * 
     * @param b byte array containing a serialized Object
     * @return Object contained in the bytes
     * @exception IOException
     * @exception ClassNotFoundException
     */
    protected Object readExternalFormFromBytes(byte[] b) throws IOException, ClassNotFoundException {
        ByteArrayInputStream stream = new ByteArrayInputStream(b);
        return readExternalFormFromStream(stream);
    }

    protected boolean skipSerializedCanonicalTests() {
        return Boolean.getBoolean("org.apache.commons.collections:with-clover");
    }

    // private implementation
    //-----------------------------------------------------------------------
    private Object readExternalFormFromStream(InputStream stream) throws IOException, ClassNotFoundException {
        ObjectInputStream oStream = new ObjectInputStream(stream);
        return oStream.readObject();
    }

    private void writeExternalFormToStream(Serializable o, OutputStream stream) throws IOException {
        ObjectOutputStream oStream = new ObjectOutputStream(stream);
        oStream.writeObject(o);
    }

}

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