Debug junit test in eclipse give error

[kramer31]

Hi. When I right click on a unit test method in the Outline view of a
junit test class (i.e. it extends junit.framework.TestCase) and choose
debug as junit test, the following exception shows up in the console
and no debugging occurs:

java.lang.NoClassDefFoundError: junit/framework/Test
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadTestLoaderClass
(RemoteTestRunner.java:324)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createRawTestLoader
(RemoteTestRunner.java:314)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createLoader
(RemoteTestRunner.java:309)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.defaultInit
(RemoteTestRunner.java:287)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.init
(RemoteTestRunner.java:210)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main
(RemoteTestRunner.java:195)

Any help would be appreciated. Thanks, guys!