SLF4J: The following loggers will not work because they were created during the default configuration phase of the underlying logging system.

[dhinojosa]

Not sure that scalalogging can work in conjunction with Java code. I tested scalalogging in a project with both scala and java code (see github url below) with an underlying slf4j-simple implementation and ended up with the following statement where the following displayed:

> test 
SLF4J: The following loggers will not work because they were created
SLF4J: during the default configuration phase of the underlying logging system.
SLF4J: See also http://www.slf4j.org/codes.html#substituteLogger
SLF4J: com.evolutionnext.Person
[info] PersonSpec:
[info] Using logging with inside of a model 
[info] - should display the log file
2013-05-01T08:58:13-0600 [pool-593-thread-5] [DEBUG] com.evolutionnext.Calculator - Adding 2 and 5
[info] CalculatorSpec:
[info] Using logging with inside of a service type class, calculator 
[info] - should add two ints and display the log
[info] Passed: : Total 2, Failed 0, Errors 0, Passed 2, Skipped 0
[success] Total time: 0 s, completed May 1, 2013 8:58:13 AM

This small project has two tests, one that tests a scala object and the other a java object.
Try it out by cloning https://github.com/dhinojosa/scala_logging_study and running test. You will find that it will randomly choose which class it will apply logging to.

[dhinojosa]

More info: http://bugzilla.slf4j.org/show_bug.cgi?id=176

[blair]

I use the following code to get around this issue, was provided by this question and answer: http://stackoverflow.com/a/12095245 . The below code works for sbt 0.12.x, the Stackoverflow code looks to be for an older version of sbt.

// SLF4J initializes itself upon the first logging call.  Because sbt
// runs tests in parallel it is likely that a second thread will
// invoke a second logging call before SLF4J has completed
// initialization from the first thread's logging call, leading to
// these messages:
//   SLF4J: The following loggers will not work because they were created
//   SLF4J: during the default configuration phase of the underlying logging system.
//   SLF4J: See also http://www.slf4j.org/codes.html#substituteLogger
//   SLF4J: com.imageworks.common.concurrent.SingleThreadInfiniteLoopRunner
//
// As a workaround, load SLF4J's root logger before starting the unit
// tests [1].
//
// [1] http://stackoverflow.com/a/12095245
testOptions in Test += Tests.Setup(classLoader =>
  classLoader
    .loadClass("org.slf4j.LoggerFactory")
    .getMethod("getLogger", classLoader.loadClass("java.lang.String"))
    .invoke(null, "ROOT")
)

[dhinojosa]

Whoa. I had no idea there was that kind of setting in sbt. Thanks Blair. Heiko, your call on whether this is a fix or not. I am going to plug this in as soon as possible.

[hseeberger]

@blair, thanks for answering.

There is a simple alternative, if you don't need parallel test execution:

parallelExecution in Test := false

Closing this, because it's not a ScalaLogging issue.