/*
 * 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
 *
 *     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.flink.test.state;

import org.apache.flink.runtime.state.StateObject;

import org.junit.Test;
import org.reflections.Reflections;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Set;

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.fail;

/**
 * This test validates that all subclasses of {@link StateObject} have a proper serial version UID.
 */
public class StateHandleSerializationTest {

    @Test
    public void ensureStateHandlesHaveSerialVersionUID() throws Exception {
        Reflections reflections = new Reflections("org.apache.flink");

        // check all state handles

        @SuppressWarnings("unchecked")
        Set<Class<?>> stateHandleImplementations =
                (Set<Class<?>>) (Set<?>) reflections.getSubTypesOf(StateObject.class);

        for (Class<?> clazz : stateHandleImplementations) {
            validataSerialVersionUID(clazz);
        }
    }

    private static void validataSerialVersionUID(Class<?> clazz) {
        // all non-interface types must have a serial version UID
        if (!clazz.isInterface()) {
            assertFalse(
                    "Anonymous state handle classes have problematic serialization behavior: "
                            + clazz,
                    clazz.isAnonymousClass());

            try {
                Field versionUidField = clazz.getDeclaredField("serialVersionUID");

                // check conditions first via "if" to prevent always constructing expensive error
                // messages
                if (!(Modifier.isPrivate(versionUidField.getModifiers())
                        && Modifier.isStatic(versionUidField.getModifiers())
                        && Modifier.isFinal(versionUidField.getModifiers()))) {
                    fail(clazz.getName() + " - serialVersionUID is not 'private static final'");
                }
            } catch (NoSuchFieldException e) {
                fail(
                        "State handle implementation '"
                                + clazz.getName()
                                + "' is missing the serialVersionUID");
            }
        }
    }
}
