I have just upgraded my SpringSource Tools Suite (STS, a variant IDE of Eclipse) to the latest version (v3.6.1). Then all my JUnit unit tests can not be run again. I am getting this error:
Class not found ClassToTest
java.lang.ClassNotFoundException: ClassToTest
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
According to this blog:
ClassNotFoundException when running JUnit unit tests within Eclipse (using Maven),
it is because of some misconfiguration of Maven plugin in Eclipse. However, in STS 3.6.2 I cannot find this option “Include Modules” in the Maven plugin. How can I fix this problem and re-enable my unit tests?
OK it seems I’ll have to answer this question by myself.
The main reason for this problem is still the m2eclipse eclipse plug-in. The new version of this plugin does not support nested modules in one project. If we really need to see multiple modules we have to remove the old one from the package explorer and create a working set and import the project again using the option “import existing maven projects”. The eclipse import wizard will pop up a window and ask you which module to be imported. Then we can select all the modules and finish the import. As a result the working set will contain all the modules of your project and treat each module as a separate project, although in the workspace your modules are still in one project. By doing this it resolves all the problems that I have come across in Eclipse related to classpath, such as not being able to search a class or not being able to run the unit tests and get a java.lang.ClassNotFoundException.
For reference, here is an article to teach you how to create a working set:
Working set
I think you can import the project without creating a new working set but the working set will keep all the modules that belong to your project in one set so it is easier to organize.
I wish I had the answer two months ago so I wouldn’t have spent much time searching for a solution.