package com.twelvemonkeys.lang;
import org.junit.Test;
import java.io.*;
import java.lang.reflect.Method;
import static org.junit.Assert.*;
/**
* AbstractObjectTestCase
* <p/>
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/test/java/com/twelvemonkeys/lang/ObjectAbstractTestCase.java#1 $
*/
public abstract class ObjectAbstractTestCase {
// TODO: See com.tm.util.ObjectAbstractTestCase
// TODO: The idea is that this should be some generic base-class that
// implements the basic object tests
// TODO: Create Serializable test similar way
// TODO: Create Comparable test similar way
/**
* Returns an instance of the class we are testing.
* Implement this method to return the object to test.
*
* @return the object to test
*/
protected abstract Object makeObject();
// TODO: Can we really do serious testing with just one object?
// TODO: How can we make sure we create equal or different objects?!
//protected abstract Object makeDifferentObject(Object pObject);
//protected abstract Object makeEqualObject(Object pObject);
@Test
public void testToString() {
assertNotNull(makeObject().toString());
// TODO: What more can we test?
}
// TODO: assert that either BOTH or NONE of equals/hashcode is overridden
@Test
public void testEqualsHashCode(){
Object obj = makeObject();
Class cl = obj.getClass();
if (isEqualsOverriden(cl)) {
assertTrue("Class " + cl.getName() + " implements equals but not hashCode", isHashCodeOverriden(cl));
}
else if (isHashCodeOverriden(cl)) {
assertTrue("Class " + cl.getName() + " implements hashCode but not equals", isEqualsOverriden(cl));
}
}
protected static boolean isEqualsOverriden(Class pClass) {
return getDeclaredMethod(pClass, "equals", new Class[]{Object.class}) != null;
}
protected static boolean isHashCodeOverriden(Class pClass) {
return getDeclaredMethod(pClass, "hashCode", null) != null;
}
private static Method getDeclaredMethod(Class pClass, String pName, Class[] pArameters) {
try {
return pClass.getDeclaredMethod(pName, pArameters);
}
catch (NoSuchMethodException ignore) {
return null;
}
}
@Test
public void testObjectEqualsSelf() {
Object obj = makeObject();
assertEquals("An Object should equal itself", obj, obj);
}
@Test
public void testEqualsNull() {
Object obj = makeObject();
// NOTE: Makes sure this doesn't throw NPE either
//noinspection ObjectEqualsNull
assertFalse("An object should never equal null", obj.equals(null));
}
@Test
public void testObjectHashCodeEqualsSelfHashCode() {
Object obj = makeObject();
assertEquals("hashCode should be repeatable", obj.hashCode(), obj.hashCode());
}
@Test
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());
}
// TODO: Make sure we create at least one equal object, and one different object
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 testFinalize() {
// TODO: Implement
}
*/
////////////////////////////////////////////////////////////////////////////
// Cloneable interface
@Test
public void testClone() throws Exception {
Object obj = makeObject();
if (obj instanceof Cloneable) {
Class cl = obj.getClass();
Method clone = findMethod(cl, "clone");
// Disregard protected modifier
// NOTE: This will throw a SecurityException if a SecurityManager
// disallows access, but should not happen in a test context
if (!clone.isAccessible()) {
clone.setAccessible(true);
}
Object cloned = clone.invoke(obj);
assertNotNull("Cloned object should never be null", cloned);
// TODO: This can only be asserted if equals() test is based on
// value equality, not reference (identity) equality
// Maybe it's possible to do a reflective introspection of
// the objects fields?
if (isHashCodeOverriden(cl)) {
assertEquals("Cloned object not equal", obj, cloned);
}
}
}
private static Method findMethod(Class pClass, String pName) throws NoSuchMethodException {
if (pClass == null) {
throw new IllegalArgumentException("class == null");
}
if (pName == null) {
throw new IllegalArgumentException("name == null");
}
Class cl = pClass;
while (cl != null) {
try {
return cl.getDeclaredMethod(pName, new Class[0]);
}
catch (NoSuchMethodException e) {
}
catch (SecurityException e) {
}
cl = cl.getSuperclass();
}
throw new NoSuchMethodException(pName + " in class " + pClass.getName());
}
///////////////////////////////////////////////////////////////////////////
// Serializable interface
@Test
public void testSerializeDeserializeThenCompare() throws Exception {
Object obj = makeObject();
if (obj instanceof Serializable) {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(buffer);
try {
out.writeObject(obj);
}
finally {
out.close();
}
Object dest;
ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(buffer.toByteArray()));
try {
dest = in.readObject();
}
finally {
in.close();
}
// TODO: This can only be asserted if equals() test is based on
// value equality, not reference (identity) equality
// Maybe it's possible to do a reflective introspection of
// the objects fields?
if (isEqualsOverriden(obj.getClass())) {
assertEquals("obj != deserialize(serialize(obj))", obj, dest);
}
}
}
/**
* Sanity check method, makes sure that any {@code Serializable}
* class can be serialized and de-serialized in memory,
* using the handy makeObject() method
*
* @throws java.io.IOException
* @throws ClassNotFoundException
*/
@Test
public void testSimpleSerialization() throws Exception {
Object o = makeObject();
if (o instanceof Serializable) {
byte[] object = writeExternalFormToBytes((Serializable) o);
readExternalFormFromBytes(object);
}
}
/**
* Write a Serializable or Externalizable object as
* a file at the given path.
* <em>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)</em>
*
* @param o Object to serialize
* @param path path to write the serialized Object
* @exception java.io.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 java.io.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 java.io.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 java.io.IOException
* @exception ClassNotFoundException
*/
protected Object readExternalFormFromBytes(byte[] b) throws IOException, ClassNotFoundException {
ByteArrayInputStream stream = new ByteArrayInputStream(b);
return readExternalFormFromStream(stream);
}
// 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);
}
public static final class SanityTestTestCase extends ObjectAbstractTestCase {
protected Object makeObject() {
return new Cloneable() {};
}
}
}