log4j-core/src/test/java/org/apache/logging/log4j/core/LogEventFactoryTest.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
 *
 *      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.logging.log4j.core;

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

import java.lang.reflect.Field;
import java.util.List;

import org.apache.commons.lang3.reflect.FieldUtils;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.core.config.LoggerConfig;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.impl.DefaultLogEventFactory;
import org.apache.logging.log4j.core.impl.Log4jLogEvent;
import org.apache.logging.log4j.core.impl.LogEventFactory;
import org.apache.logging.log4j.core.util.Constants;
import org.apache.logging.log4j.core.junit.LoggerContextRule;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.test.appender.ListAppender;
import org.junit.Before;
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.rules.RuleChain;
import org.junit.runners.model.Statement;

/**
 *
 */
public class LogEventFactoryTest {

    private static final String CONFIG = "log4j2-config.xml";
    private static final LoggerContextRule context = new LoggerContextRule(CONFIG);

    private ListAppender app;

    // this would look so cool using lambdas
    @ClassRule
    public static RuleChain chain = RuleChain.outerRule((base, description) -> new Statement() {
        @Override
        public void evaluate() throws Throwable {
            System.setProperty(Constants.LOG4J_LOG_EVENT_FACTORY, TestLogEventFactory.class.getName());
            resetLogEventFactory(new TestLogEventFactory());
            try {
                base.evaluate();
            } finally {
                System.clearProperty(Constants.LOG4J_LOG_EVENT_FACTORY);
                resetLogEventFactory(new DefaultLogEventFactory());
            }
        }

        private void resetLogEventFactory(final LogEventFactory logEventFactory) throws IllegalAccessException {
            final Field field = FieldUtils.getField(LoggerConfig.class, "LOG_EVENT_FACTORY", true);
            FieldUtils.removeFinalModifier(field);
            FieldUtils.writeStaticField(field, logEventFactory, false);
        }
    }).around(context);

    @Before
    public void before() {
        app = context.getListAppender("List").clear();
    }

    @Test
    public void testEvent() {
        final org.apache.logging.log4j.Logger logger = context.getLogger("org.apache.test.LogEventFactory");
        logger.error("error message");
        final List<LogEvent> events = app.getEvents();
        assertNotNull("No events", events);
        assertEquals("Incorrect number of events. Expected 1, actual " + events.size(), 1, events.size());
        final LogEvent event = events.get(0);
        assertEquals("TestLogEventFactory wasn't used", "Test", event.getLoggerName());
    }

    public static class TestLogEventFactory implements LogEventFactory {

        @Override
        public LogEvent createEvent(final String loggerName, final Marker marker,
                                    final String fqcn, final Level level, final Message data,
                                    final List<Property> properties, final Throwable t) {
            return new Log4jLogEvent("Test", marker, fqcn, level, data, properties, t);
        }
    }
}