The jarc tool supports running Junit tests as part of a jar build since version 0.2.5. Since then when a unit test fails during a jar build the output of the jarc tool looked like this:
$ jarc reload
testInit(org.implementers.nio.channels.reload.ReloadNodeTest)
java.lang.AssertionError:
at org.junit.Assert.fail(Assert.java:91)
at org.junit.Assert.fail(Assert.java:98)
at org.implementers.nio.channels.reload.ReloadNodeTest.testInit(ReloadNodeTest.java:150)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
The problem with this output is that it is not well integrated with other tools. Gvim for example cannot parse this output to display the current junit test file and line and worst, the output is lost so I had to remember the line number to be able to find where the test failed.
One way to fix this could have been to change the error format string in Gvim to parse the output, but that would not helped for other tools. So instead of this, jarc v0.2.20 is now formatting Junit errors with the same format than Java compilation errors, so the error above looks like this now:
$ jarc reload
../src/share/classes/org/implementers/nio/channels/reload/ReloadNodeTest.java:150: java.lang.AssertionError:
Now Gvim and other tools can parse the output and display directly the line that failed.