com.swirlds.common.test.logging.MockAppender Maven / Gradle / Ivy
/*
* Copyright (C) 2023 Hedera Hashgraph, LLC
*
* Licensed 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 com.swirlds.common.test.logging;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.appender.AbstractAppender;
/**
* This class intended to be used in unit tests to capture log messages. It is thread-safe.
* To make it work, add the following to your test:
* {@code
* final MockAppender mockAppender = new MockAppender();
* Logger logger = (Logger) LogManager.getLogger(DataFileCollection.class);
* mockAppender.start();
* logger.addAppender(mockAppender);
* }
* Then call {@code mockAppender.get()} to get the log message.
* After the test, call {@code mockAppender.stop()} to clean up.
*
*/
public class MockAppender extends AbstractAppender {
private final List messages = new CopyOnWriteArrayList<>();
public MockAppender(@NonNull final String name) {
super("MockAppender-" + name, null, null, true, null);
}
/**
* {@inheritDoc}
*/
@Override
public void append(@NonNull final LogEvent event) {
if (isStarted()) {
messages.add(String.format(
"%s - %s - %s",
event.getMarker().getName(),
event.getLevel(),
event.getMessage().getFormattedMessage()));
}
}
/**
* Get the number of captured log messages.
* @return the number of captured log messages
*/
public int size() {
return messages.size();
}
/**
* Clear previously captured the log messages.
*/
public void clear() {
messages.clear();
}
/**
* Get the log message at the specified index.
* @param index the index of the message
* @return the log message
*/
public String get(final int index) {
return messages.get(index);
}
/**
* {@inheritDoc}
*/
@Override
public void stop() {
messages.clear();
super.stop();
}
}