AbstractObjectTest.java
/*
* 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
*
* https://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.collections4;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
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;
import java.nio.file.Files;
import java.nio.file.Paths;
import org.junit.jupiter.api.Test;
/**
* Tests {@link Object}.
* <p>
* To use, simply extend this class, and implement the {@link #makeObject()} method.
* </p>
* <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.
* </p>
*/
public abstract class AbstractObjectTest extends BulkTest {
/** Current major release for Collections */
public static final int COLLECTIONS_MAJOR_VERSION = 4;
protected String getCanonicalEmptyCollectionName(final Object object) {
final StringBuilder retval = new StringBuilder();
retval.append(TEST_DATA_PATH);
String colName = object.getClass().getName();
colName = colName.substring(colName.lastIndexOf(".") + 1);
retval.append(colName);
retval.append(".emptyCollection.version");
retval.append(getCompatibilityVersion());
retval.append(".obj");
return retval.toString();
}
protected String getCanonicalFullCollectionName(final Object object) {
final StringBuilder retval = new StringBuilder();
retval.append(TEST_DATA_PATH);
String colName = object.getClass().getName();
colName = colName.substring(colName.lastIndexOf(".") + 1);
retval.append(colName);
retval.append(".fullCollection.version");
retval.append(getCompatibilityVersion());
retval.append(".obj");
return retval.toString();
}
/**
* Gets the version of Collections that this object tries to maintain serialization compatibility with. Defaults to 4, due to the package change to
* collections4 introduced in version 4. This constant makes it possible for TestMap (and other subclasses, if necessary) to automatically check SCM 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 "4";
}
/**
* Returns true to indicate that the collection supports equals() comparisons. This implementation returns true;
*/
public boolean isEqualsCheckable() {
return true;
}
/**
* Is serialization testing supported. Default is true.
*/
public boolean isTestSerialization() {
return true;
}
/**
* Implement this method to return the object to test.
*
* @return The object to test.
*/
public abstract Object makeObject();
/**
* Reads 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.
* @throws IOException
* @throws ClassNotFoundException
*/
protected Object readExternalFormFromBytes(final byte[] b) throws IOException, ClassNotFoundException {
final ByteArrayInputStream stream = new ByteArrayInputStream(b);
return readExternalFormFromStream(stream);
}
/**
* Reads a Serialized or Externalized Object from disk. Useful for creating compatibility tests between different SCM versions of the same class
*
* @param path path to the serialized Object.
* @return The Object at the given path.
* @throws IOException
* @throws ClassNotFoundException
*/
protected Object readExternalFormFromDisk(final String path) throws IOException, ClassNotFoundException {
try (InputStream stream = Files.newInputStream(Paths.get(path))) {
return readExternalFormFromStream(stream);
}
}
// private implementation
private Object readExternalFormFromStream(final InputStream stream) throws IOException, ClassNotFoundException {
return new ObjectInputStream(stream).readObject();
}
protected boolean skipSerializedCanonicalTests() {
return Boolean.getBoolean("org.apache.commons.collections:with-clover");
}
/**
* Override this method if a subclass is testing an object that cannot serialize an "empty" Collection. (for example 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. (for example Comparators have no contents)
*
* @return true
*/
public boolean supportsFullCollections() {
return true;
}
/**
* Tests serialization by comparing against a previously stored version in SCM. If the test object is serializable, confirm that a canonical form exists.
*/
@Test
public void testCanonicalEmptyCollectionExists() {
if (supportsEmptyCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
final Object object = makeObject();
if (object instanceof Serializable) {
final String name = getCanonicalEmptyCollectionName(object);
assertTrue(new File(name).exists(), "Canonical empty collection (" + name + ") is not in SCM");
}
}
}
/**
* Tests serialization by comparing against a previously stored version in SCM. If the test object is serializable, confirm that a canonical form exists.
*/
@Test
public void testCanonicalFullCollectionExists() {
if (supportsFullCollections() && isTestSerialization() && !skipSerializedCanonicalTests()) {
final Object object = makeObject();
if (object instanceof Serializable) {
final String name = getCanonicalFullCollectionName(object);
assertTrue(new File(name).exists(), "Canonical full collection (" + name + ") is not in SCM");
}
}
}
@Test
void testEqualsNull() {
final Object obj = makeObject();
assertFalse(obj.equals(null)); // make sure this doesn't throw NPE either
}
@Test
void testObjectEqualsSelf() {
final Object obj = makeObject();
assertEquals(obj, obj, "A Object should equal itself");
}
@Test
void testObjectHashCodeEqualsContract() {
final Object obj1 = makeObject();
if (obj1.equals(obj1)) {
assertEquals(obj1.hashCode(), obj1.hashCode(), "[1] When two objects are equal, their hashCodes should be also.");
}
final Object obj2 = makeObject();
if (obj1.equals(obj2)) {
assertEquals(obj1.hashCode(), obj2.hashCode(), "[2] When two objects are equal, their hashCodes should be also.");
assertEquals(obj2, obj1, "When obj1.equals(obj2) is true, then obj2.equals(obj1) should also be true");
}
}
@Test
void testObjectHashCodeEqualsSelfHashCode() {
final Object obj = makeObject();
assertEquals(obj.hashCode(), obj.hashCode(), "hashCode should be repeatable");
}
@Test
public void testSerializeDeserializeThenCompare() throws Exception {
final Object obj = makeObject();
if (obj instanceof Serializable && isTestSerialization()) {
final Object dest = serializeDeserialize(obj);
if (isEqualsCheckable()) {
assertEquals(obj, dest, "obj != deserialize(serialize(obj))");
}
}
}
/**
* 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
*/
@Test
public void testSimpleSerialization() throws Exception {
final Object o = makeObject();
if (o instanceof Serializable && isTestSerialization()) {
readExternalFormFromBytes(writeExternalFormToBytes((Serializable) o));
}
}
/**
* 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.
* @throws IOException
*/
protected byte[] writeExternalFormToBytes(final Serializable o) throws IOException {
final ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
writeExternalFormToStream(o, byteStream);
return byteStream.toByteArray();
}
/**
* Writes 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 SCM 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.
* @throws IOException
*/
protected void writeExternalFormToDisk(final Serializable o, final String path) throws IOException {
try (FileOutputStream fileStream = new FileOutputStream(path)) {
writeExternalFormToStream(o, fileStream);
}
}
private void writeExternalFormToStream(final Serializable o, final OutputStream stream) throws IOException {
new ObjectOutputStream(stream).writeObject(o);
}
}