src/test/org/apache/commons/functor/BaseFunctorTest.java

/*
 * Copyright 2003,2004 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.functor;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import junit.framework.TestCase;

/**
 * @version $Revision$ $Date$
 * @author Rodney Waldhoff
 */
public abstract class BaseFunctorTest extends TestCase {

    // Conventional
    // ------------------------------------------------------------------------

    public BaseFunctorTest(String testName) {
        super(testName);
    }

    // Lifecycle
    // ------------------------------------------------------------------------

    public void setUp() throws Exception {
        super.setUp();
    }

    public void tearDown() throws Exception {
        super.tearDown();
    }

    // Framework
    // ------------------------------------------------------------------------
    
    protected abstract Object makeFunctor() throws Exception;
   
    // Tests
    // ------------------------------------------------------------------------    

    public final void testObjectEquals() throws Exception {
        Object obj = makeFunctor();
        assertEquals("equals must be reflexive",obj,obj);
        assertEquals("hashCode must be reflexive",obj.hashCode(),obj.hashCode());
        assertTrue(! obj.equals(null) ); // should be able to compare to null
        
        Object obj2 = makeFunctor();
        if(obj.equals(obj2)) {
            assertEquals("equals implies hash equals",obj.hashCode(),obj2.hashCode());
            assertEquals("equals must be symmetric",obj2,obj);
        } else {
            assertTrue("equals must be symmetric",! obj2.equals(obj));
        }
    }

    public final void testSerializeDeserializeThenCompare() throws Exception {
        Object obj = makeFunctor();
        if(obj instanceof Serializable) {
            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();
            assertEquals("obj != deserialize(serialize(obj))",obj,dest);
            assertEquals("obj.hash != deserialize(serialize(obj.hash))",obj.hashCode(),dest.hashCode());
        }
    }

    public void testToStringIsOverridden() throws Exception {
        Object obj = makeFunctor();
        assertNotNull("toString should never return null",obj.toString());
        assertTrue(
            obj.getClass().getName()  + " should override toString(), found \"" + obj.toString() + "\"",
            !obj.toString().equals(objectToString(obj)));
    }

    // protected utils
    // ------------------------------------------------------------------------
    public static void assertObjectsAreEqual(Object a, Object b) {
        assertEquals(a,b);
        assertEquals(b,a);
        assertEquals(a.hashCode(),b.hashCode()); 
        assertEquals(a.toString(),b.toString()); // not strictly required
    }
    
    public static void assertObjectsAreNotEqual(Object a, Object b) {
        assertTrue(!a.equals(b));
        assertTrue(!b.equals(a));
        assertTrue(a.hashCode() != b.hashCode()); // not strictly required
        assertTrue(!a.toString().equals(b.toString())); // not strictly required
    }
    
    // private utils
    // ------------------------------------------------------------------------
    private String objectToString(Object obj) {
        return obj.getClass().getName() + "@" + Integer.toHexString(obj.hashCode());
    }
}