Test for deserialization issue with kryo and class extending HashMap

ValueObjectFix.java

package de.javakaffee.web.msm.serializer.kryo;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertNotNull;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.testng.annotations.Test;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.serialize.MapSerializer;

import de.javakaffee.web.msm.MemcachedBackupSession;

public class ValueObjectFix {
	
	public static class ValueObjectImplSerializerRegistration implements KryoCustomization {

		@Override
		public void customize(final Kryo kryo) {
	        kryo.register(ValueObjectImpl.class, new MapSerializer(kryo) {
				@Override
	        	@SuppressWarnings({ "rawtypes", "unchecked" })
	        	public <T> T newInstance(final Kryo kryo, final Class<T> type) {
	        		return (T) new ValueObjectImpl();
	        	}
	        });
		}
		
	}

    @Test
    public void testDeserializationError() {

        final KryoTranscoderFactory transcoderFactory = new KryoTranscoderFactory();
        transcoderFactory.setCustomConverterClassNames(new String[] {ValueObjectImplSerializerRegistration.class.getName()});
		final KryoTranscoder transcoder = transcoderFactory.createTranscoder(Thread.currentThread().getContextClassLoader());

        final ValueObjectImpl<String, String> obj = new ValueObjectImpl<String, String>();
        obj.put("foo", "bar");
        
        // serialize one instance
        final MemcachedBackupSession memcachedBackupSession = new MemcachedBackupSession();
        final Map<String, Object> attributes = new ConcurrentHashMap<String, Object>();
        attributes.put("obj", obj);

        final byte[] data = transcoder.serializeAttributes(memcachedBackupSession, attributes);
        final Map<String, Object> deserializeAttributes = transcoder.deserializeAttributes(data);

        final Object actual = deserializeAttributes.get("obj");
        assertNotNull(actual);
        assertEquals(actual, obj);
    }

    @SuppressWarnings("serial")
    static class ValueObjectImpl<K, V> extends HashMap<K, V> {

        @Override
        public V get(final Object key) {
            return key != null ? super.get(key): null;
        }

        @Override
        public V put(final K key, final V value) {
            return key != null ? super.put(key, value) : null;
        }
    }

}

ValueObjectTest.java

package de.javakaffee.web.msm.serializer.kryo;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertNotNull;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.testng.annotations.Test;
import com.esotericsoftware.kryo.serialize.MapSerializer;
import de.javakaffee.web.msm.MemcachedBackupSession;

public class ValueObjectTest {

    @Test
    public void testDeserializationError() {

        final KryoTranscoder transcoder = new KryoTranscoderFactory().createTranscoder(Thread.currentThread().getContextClassLoader());

        final ValueObjectImpl<String, String> obj = new ValueObjectImpl<String, String>();
        obj.put("foo", "bar");
        
        // serialize one instance
        final MemcachedBackupSession memcachedBackupSession = new MemcachedBackupSession();
        final Map<String, Object> attributes = new ConcurrentHashMap<String, Object>();
        attributes.put("obj", obj);

        final byte[] data = transcoder.serializeAttributes(memcachedBackupSession, attributes);
        final Map<String, Object> deserializeAttributes = transcoder.deserializeAttributes(data);

        final Object actual = deserializeAttributes.get("obj");
        assertNotNull(actual);
        assertEquals(actual, obj);
    }

    @SuppressWarnings("serial")
    public static class ValueObjectImpl<K, V> extends HashMap<K, V> {

        @Override
        public V get(final Object key) {
            return key != null ? super.get(key): null;
        }

        @Override
        public V put(final K key, final V value) {
            return key != null ? super.put(key, value) : null;
        }
    }

}