Fix for ClassNotFoundException in PDE JUnit Test Runner

When trying to run a PDE JUnit test suite in Eclipse, the requested unit test is not executed, the hosted workbench terminates immediately with the following error to the console (where org.epic.perleditor.editors.TestEditorAssociation is the name of the unit test). The plug-in which contains the allegedly missing class is present in the workspace. (This error also falls into the "it used to work before" category.)

Class not found org.epic.perleditor.editors.TestEditorAssociation
java.lang.ClassNotFoundException: org.epic.perleditor.editors.TestEditorAssociation
 at org.eclipse.osgi.framework.internal.core.BundleLoader.findClassInternal(BundleLoader.java:481)
 at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:397)
 at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:385)
 at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:87)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
 at org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:313)
 at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:227)
 at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1274)
 at org.eclipse.pde.internal.junit.runtime.RemotePluginTestRunner$BundleClassLoader.findClass(RemotePluginTestRunner.java:38)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClass(RemoteTestRunner.java:683)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClasses(RemoteTestRunner.java:425)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:445)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
 at org.eclipse.pde.internal.junit.runtime.RemotePluginTestRunner.main(RemotePluginTestRunner.java:62)
 at org.eclipse.pde.internal.junit.runtime.UITestApplication$1.run(UITestApplication.java:114)
 at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
 at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:133)
 at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3378)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3036)
 at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2382)
 at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2346)
 at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2198)
 at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:493)
 at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
 at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:488)
 at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
 at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
 at org.eclipse.pde.internal.junit.runtime.UITestApplication.start(UITestApplication.java:46)
 at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)
 at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
 at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
 at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:386)
 at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
 at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
 at org.eclipse.equinox.launcher.Main.run(Main.java:1236)
 at org.eclipse.equinox.launcher.Main.main(Main.java:1212)

Solution: edit META-INF/MANIFEST.MF of the plug-in containing the not found class and add the class folder (i.e. bin) to the Bundle-ClassPath: directive, like so:

Bundle-ClassPath: cglib-full-2.0.2.jar,
 easymock.jar,
 bin/

If you need to debug this problem in more detail, the method responsible for finding the class (which works in a good configuration, and fails otherwise) is org.eclipse.osgi.framework.internal.core.BundleLoader.findLocalClass.