LambdaSerializationTest.java

package lambdaserialization;

import org.junit.Test;

import java.io.Serializable;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.function.Function;

import static lambdaserialization.Utils.serializeAndDeserialize;
import static org.junit.Assert.assertEquals;

public class LambdaSerializationTest {

    @Test
    public void testGeneratedClassEquality_useRegularSerialization() throws Exception {
        int capturedDelta = 1;
        Function<Integer, Integer> originFunction = (Function<Integer, Integer> & Serializable) i -> i + capturedDelta;
        System.out.println(originFunction);

        Function<Integer, Integer> deserializedFunction = serializeAndDeserialize(originFunction);
        System.out.println(deserializedFunction);
        assertEquals(originFunction.getClass(), deserializedFunction.getClass());
    }

    @Test
    public void testGeneratedClassEquality_useHackedMethod() throws Exception {
        int delta = 1;
        Function<Integer, Integer> originFunction = (Function<Integer, Integer> & Serializable) i -> i + delta;
        System.out.println(originFunction);

        SerializedLambda serializedLambda = createSerializedLambda(originFunction);
        System.out.println(serializedLambda);

        Function<Integer, Integer> deserializedFunction = deserializeLambda(serializedLambda);
        System.out.println(deserializedFunction);

        assertEquals(originFunction.getClass(), deserializedFunction.getClass());
    }

    @Test
    public void testGeneratedClassEquality_mixed() throws Exception {
        int delta = 1;
        Function<Integer, Integer> originFunction = (Function<Integer, Integer> & Serializable) i -> i + delta;
        System.out.println(originFunction);


        Function<Integer, Integer> deserializedFunction_regular = serializeAndDeserialize(originFunction);

        SerializedLambda serializedLambda = createSerializedLambda(originFunction);
        Function<Integer, Integer> deserializedFunction_hacked = deserializeLambda(serializedLambda);

        assertEquals(deserializedFunction_regular.getClass(), deserializedFunction_hacked.getClass());
    }

    private static Function<Integer, Integer> deserializeLambda(SerializedLambda serializedLambda) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
        Function<Integer, Integer> f;Method deserializeLambdaMethod = LambdaSerializationTest.class.getDeclaredMethod("$deserializeLambda$", SerializedLambda.class);
        deserializeLambdaMethod.setAccessible(true);
        f = (Function<Integer, Integer>) deserializeLambdaMethod.invoke(null, serializedLambda);
        return f;
    }

    private static SerializedLambda createSerializedLambda(Object f) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
        Method writeReplaceMethod = f.getClass().getDeclaredMethod("writeReplace");
        writeReplaceMethod.setAccessible(true);
        return (SerializedLambda) writeReplaceMethod.invoke(f);
    }
}