Specifying -Djava.ext.dirs causes classpath problem

[bcowan]

If the java "ext" directory is specified on the command line, JUnit is unable to find the unit test classes. Whereas, if "classpath" is used, everything is fine. When tests depend on a number of 3rd party libraries, the "ext" directory approach is far preferable.

For example:

java -classpath /home/cowan/src/atst/lib/java/classes
-Djava.ext.dirs=/home/cowan/src/atst/lib/java/ext org.junit.runner.JUnitCore atst.cs.test.TestAll

results in:
JUnit version 4.7
Could not find class: atst.cs.test.TestAll

The strange thing is that if the verbose flag is used, Java even logs that it successfully loaded the TestAll class from the appropriate directory before later displaying the error.

If the command line is modified to:

java -classpath
/home/cowan/src/atst/lib/java/classes:/home/cowan/src/atst/lib/java/ext/junit.jar
org.junit.runner.JUnitCore atst.cs.test.TestAll

everything works as expected.

-Djava.ext.dirs seems to be causing classpath/classloader issues.

[godmar]

I agree this is a problem. The reason is that JUnit uses Class.forName() to look for test class. When org.junit.runner.JUnitCore is in the boot classpath or in the extension path, the system loader will load JUnitCore, and therefore all test classes would have to be in the boot or extension path.

JUnit should respect the -classpath setting by using its own Application loader, even if junit.jar is in the boot or extension path.

As a short-gap measure, JUnit should report the error more verbosely - report the class loader you used.

[dsaff]

Is this still a problem? Sorry it's languished so long.

[kcooney]

I think this can be fixed by finding all references of Class.forName() and updating them to use Thread.currentThread().getContextClassLoader() to load the class. See http://www.javaworld.com/article/2077344/core-java/find-a-way-out-of-the-classloader-maze.html

[junit-builds]

JUnit 4 is now in maintenance mode.

At this point, only critical bugs and security issues will be fixed.

The team has therefore decided to close this issue.