testobject.java

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/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * 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.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;

/**
 * Tests base {@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.
 *
 * @author Rodney Waldhoff
 * @version $Id: TestObject.java,v 1.13.2.1 2004/05/22 12:14:05 scolebourne Exp $
 */
public abstract class TestObject extends BulkTest {
    public TestObject(String testName) {
        super(testName);
    }

    // current major release for Collections
    public static final int COLLECTIONS_MAJOR_VERSION = 2;

    /**
     * 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.
     * Defaults to 1, the earliest Collections version.  (Note: some
     * collections did not even exist in this version).
     * 
     * @return 1
     */
    public int getCompatibilityVersion() {
        return 1;
    }

    /**
     * Return a new, empty {@link Object} to used for testing.
     */
    public abstract Object makeObject();

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

    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));
        }
    }

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

    /**
     * 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();
    }

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

    /**
     * Reads a Serialized or Externalized Object from disk.
     * Useful for creating compatibility tests betweeen
     * 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);
    }

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

    public 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();
    }

    public 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();
    }

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

    /**
     * If the test object is serializable, confirm that 
     * a canonical form exists in CVS
     * 
     */
    public void testCanonicalEmptyCollectionExists() {
        if (!supportsEmptyCollections()) {
            return;
        }

        Object object = makeObject();
        if (!(object instanceof Serializable)) {
            return;
        }
        String name = getCanonicalEmptyCollectionName(object);
        assertTrue("Canonical empty collection is not in CVS",
                   new File(name).exists());
    }

    /**
     * If the test object is serializable, confirm that 
     * a canonical form exists in CVS
     * 
     */
    public void testCanonicalFullCollectionExists() {
        if (!supportsFullCollections()) {
            return;
        }
        
        Object object = makeObject();
        if (!(object instanceof Serializable)) {
            return;
        }
        String name = getCanonicalFullCollectionName(object);
        assertTrue("Canonical full collection is not in CVS",
                   new File(name).exists());
    }
}