Steps to reproduce

In Eclipse Package Explorer:

• Right-Click package 'net.sf.j2s.test.junit'
• Select 'Run As > Java2Script Unit Test'

A 'Problem occured' dialog appears with the message:

'Launching net.sf.j2s.test.junit' has encountered a problem

An internal error occurred during: "Launching net.sf.j2s.test.junit".
org.eclipse.jdt.internal.core.PackageFragment cannot be cast to org.eclipse.jdt.core.IType

The error log contains this entry:

!MESSAGE An internal error occurred during: "Launching net.sf.j2s.test.junit".
!STACK 0
java.lang.ClassCastException: org.eclipse.jdt.internal.core.PackageFragment cannot be cast to org.eclipse.jdt.core.IType
at net.sf.j2s.ui.launching.J2SLaunchingUtil.launchingJ2SUnit(J2SLaunchingUtil.java:149)
at net.sf.j2s.ui.launching.J2SUnitConfigurationDelegate.launch(J2SUnitConfigurationDelegate.java:21)
at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:885)
at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:739)
at org.eclipse.debug.internal.ui.DebugUIPlugin.buildAndLaunch(DebugUIPlugin.java:1039)
at org.eclipse.debug.internal.ui.DebugUIPlugin$8.run(DebugUIPlugin.java:1256)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

(Running individual test classes works fine)