How to configure log4j.properties for SpringJUnit4ClassRunner?
Suddenly this keeps happening during a JUnit test. Everything was working, I wrote some new tests and this error occured. If I revert it, it won't go away. Why is that?
log4j:WARN No appenders could be found for logger (org.springframework.test.context.junit4.SpringJUnit4ClassRunner).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Answer
The new tests you wrote (directly or indirectly) use classes that log using Log4j.
Log4J needs to be configured for this logging to work properly.
Put a log4j.properties (or log4j.xml) file in the root of your test classpath.
It should have some basic configuration such as
# Set root logger level to DEBUG and its only appender to A1.
log4j.rootLogger=DEBUG, A1
# A1 is set to be a ConsoleAppender.
log4j.appender.A1=org.apache.log4j.ConsoleAppender
# A1 uses PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
# An alternative logging format:
# log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1} - %m%n
An appender outputs to the console by default, but you can also explicitly set the target like this:
log4j.appender.A1.Target=System.out
This will redirect all output in a nice format to the console. More info can be found here in the Log4J manual,
Log4J Logging will then be properly configured and this warning will disappear.