How to set the Loglevel for a JUnit Test

Question

I am using java logging in my classes.

Example:

public class MyClass  {
    private static Logger logger = Logger.getLogger(MyClass.class.getName());
    ....
}

When I am writing a JUnit Test for that class, I would like to set the Loglevel to 'FINE'. I tried:

@Before
public void setup() throws PluginException {
    Logger.getGlobal().setLevel(Level.FINE);
    ....
}

But this has no effect. How can I control the loglevel in a JUnit Test when using Java Logging? I am running my tests using Maven.

How are you running unit tests? maven or some other way? – Krzysztof Krasoń Jul 25 '16 at 11:44 — Krzysztof Krasoń, Jul 25 '16 at 11:44
Try `Logger.getLogger("").setLevel(Level.FINE)`. – Andrew Logvinov Jul 25 '16 at 11:48 — Andrew Logvinov, Jul 25 '16 at 11:48

score 7 · Answer 1 · edited May 23 '17 at 11:54

This is the simplest, most generic way I've found to set the java.util.logging level for JUnit tests.

import java.util.logging.Level;
import java.util.logging.Logger;

import org.junit.BeforeClass;
import org.junit.Test;

public class MyTest
{
    @BeforeClass
    public static void beforeClass()
    {
        System.setProperty("java.util.logging.config.file", ClassLoader.getSystemResource("logging.properties").getPath());
    }

    @Test
    public void test00a()
    {
        Logger.getLogger(MyTest.class.getName()).log(Level.FINE, "J.U.L. test");
    }
}

In src/test/resources create logging.properties (.level must be the first line):

.level=FINEST
handlers=java.util.logging.ConsoleHandler
java.util.logging.ConsoleHandler.level=FINEST

When you run the unit test(s) in this class, you should see:

May 01, 2017 12:17:12 PM MyTest test00a

FINE: J.U.L. test

score 0 · Answer 2 · answered Jul 25 '16 at 11:55

0

Logger.getLogger() documentation:

Find or create a logger for a named subsystem. If a logger has already been created with the given name it is returned. Otherwise a new logger is created.

In your case, Logger.getLogger() with the same name gives you the same logger-instance. Therefore, you can get the logger and set its level with

@Before
public void setup() throws PluginException {
    Logger.getLogger(MyClass.class.getName()).setLevel(Level.FINE);
    ...
}

Just make sure to set it back in the @After-method later.

answered Jul 25 '16 at 11:55

TMichelsen

317
1
7

3

Thanks for your answer, but this did not work. Maybe I need to set also some additional global log level? I debugged the code and my class is now logging - but not into the standard output. I am running tests with Maven. – Ralph Jul 26 '16 at 12:51
@Ralph See [this answer](https://stackoverflow.com/a/43722641/2074605) for a complete example that works at the class level. – vallismortis Jul 05 '18 at 11:10

piepera · Answer 3 · 2019-10-17T20:52:53.590

To solve this problem, I defined a custom JUnit 4 rule to disable logs for a specific test:

@RequiredArgsConstructor
public class LogLevelRule extends TestWatcher {

  private Level oldLevel;
  private final Class clazz;
  private final String levelString;

  @Override
  protected void starting(Description description) {
    oldLevel = Logger.getLogger(clazz).getLevel();
    Logger.getLogger(clazz).setLevel(Level.toLevel(levelString));
  }

  @Override
  protected void finished(Description description) {
    Logger.getLogger(clazz).setLevel(oldLevel);
  }
}

This can then be enabled by declaring a @Rule of @ClassRule in the particular test:

  @ClassRule
  public static LogLevelRule logLevelRule = new LogLevelRule(MyClass.class, "OFF");

How to set the Loglevel for a JUnit Test

3 Answers3

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