Suppression of Log Message on Non-Failing Tests
Logging is important, but annoying in cases when you do not need it. On test cases, logging helps on repairs based on failing test cases. For non-failing (negative) test cases, logging messages should be suppressed, but for failing test cases it should be printed.
With JUnit, you can achieve this as follows: Using the JUnit Extensions interface. On each test execution, you disable the logging and enables and re-enable it after test execution. If the test execution was positive (aka. the test came back with an exception), you print the logging messages captured during the execution.
In logback, you can capture the the logging messages with the StringListAppender which is hang into the root logger. It stores the messages in a list of strings. The old (console) appender should be saved and remove from the root logger.
You can install the lifecycle methods globally using (a) junit-platform.properties and (b) the ServiceLoader interface. See.
junit-platform.properties
junit.jupiter.extensions.autodetection.enabled=true
META-INF/services/org.junit.jupiter.api.extension.Extension
de.uka.ilkd.key.testfixtures.TestLogMgr
de.uka.ilkd.key.testfixtures.TestLogMgr
/* This file is part of KeY - https://key-project.org
* KeY is licensed under the GNU General Public License Version 2
* SPDX-License-Identifier: GPL-2.0-only */
package de.uka.ilkd.key.testfixtures;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.ConsoleAppender;
import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
import ch.qos.logback.core.testUtil.StringListAppender;
import org.junit.jupiter.api.extension.AfterTestExecutionCallback;
import org.junit.jupiter.api.extension.BeforeTestExecutionCallback;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.slf4j.LoggerFactory;
/**
* Extension of JUnit 5 that suppress logging of non-failing tests.
*
* @author Alexander Weigl
* @version 1 (2/17/26)
*/
public class TestLogMgr implements AfterTestExecutionCallback, BeforeTestExecutionCallback {
private static ch.qos.logback.classic.Logger root =
(ch.qos.logback.classic.Logger) LoggerFactory
.getLogger(org.slf4j.Logger.ROOT_LOGGER_NAME);
private static final ConsoleAppender<ILoggingEvent> consoleAppender;
private static final StringListAppender<ILoggingEvent> listAppender =
new StringListAppender<>();
static {
consoleAppender = (ConsoleAppender<ILoggingEvent>) root.getAppender("STDOUT");
listAppender.setContext(consoleAppender.getContext());
listAppender.setLayout(
((LayoutWrappingEncoder<ILoggingEvent>) consoleAppender.getEncoder()).getLayout());
listAppender.start();
}
@Override
public void afterTestExecution(ExtensionContext context) {
root.detachAppender(listAppender);
root.addAppender(consoleAppender);
if (context.getExecutionException().isPresent()) {
for (var s : listAppender.strList) {
System.out.print(s);
}
System.out.flush();
}
listAppender.strList.clear();
}
@Override
public void beforeTestExecution(ExtensionContext context) {
System.out.flush();
root.detachAppender(consoleAppender);
root.addAppender(listAppender);
}
}
This based on the initial configuration of logback.xml:
<configuration>
<statusListener class="ch.qos.logback.core.status.NopStatusListener" />
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<file>key.log</file>
<append>false</append>
<encoder>
<pattern>%-10relative %-5level %-15thread %-25logger{5} %msg %ex%n</pattern>
</encoder>
</appender>
<root level="DEBUG">
<appender-ref ref="STDOUT"/>
</root>
</configuration>
You can setup this once in the textFixtures using Gradles plugin java-test-fixtures.