Solution for ClassNotFoundException with JUnit and Ant

Posted under Java by Anthony Chaves on December 1st, 2006

Last time I sat down to work on a new build.xml file I ran into a ClassNotFoundException while trying to run my JUnit tests. It turns out that a few other people have experienced the same problem, too. None of the pages I found from Google had a solution posted so I will post the solution I came up with. The problem that I am trying to solve is:

Testsuite: net.anthonychaves.test.geoip.locator.LocatorServiceTest
Tests run: 1, Failures: 0, Errors: 1, Time elapsed: 3.634 sec

Testcase: testGetLocation took 3.622 sec
Caused an ERROR
net/anthonychaves/geoip/locator/LocatorService
java.lang.NoClassDefFoundError: net/anthonychaves/geoip/locator/LocatorService
at net.anthonychaves.test.geoip.locator.LocatorServiceTest.setUp(Unknown Source)
at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423)
at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137)

The first thing I did was fire up Ant with the -debug flag so I could examine the classpath carefully. My *Test.class files were definitely in the classpath passed to the forked JVM but they were not found. Because I was using a forked JVM and doing so erases a lot of useful information I set fork=”no” and ran it again. This time I got:

Finding class net.anthonychaves.test.geoip.locator.LocatorServiceTest
Ignoring Exception java.util.zip.ZipException: error in opening zip file reading resource net/anthonychaves/test/geoip/locator/LocatorServiceTest.class from /home/anthony/workspace/IPAddressLocatorClient/build/classes/net/anthonychaves/test/geoip/locator/LocatorHelpersTest.class

The good news is that this is a message that I did not get while running the test in a forked JVM. The better news is I had a good idea what the exception means. Apparently Ant expects all the classes to be in Jar files rather than in directories on the file system. A few tweaks to my build.xml file and it looked like this: build.xml

Now I’m creating two jar files, one for the application and one for the unit tests. After the unit test jar is created I run them in the JUnit task after setting the classpath with the test jar file. I would have liked to put off creating the application jar file until I knew the JUnit tests passed but that is not an option at this point. I don’t feel strongly enough to make it an option either. I have a 2.4 GHz Pentium 4 computer, I can afford to make a few extra jar files.

When debugging Ant build problems run with the -debug flag and turn off JVM forking if possible. If I didn’t do those two things I would still be debugging.

9 Responses

  1. Stuart wrote on December 19th, 2006 at 2:55 pm:

    The link to your build.xml file is bad.

    Would really like to see it as I am having the same issues with my code.

  2. Bert Heymans wrote on February 21st, 2007 at 9:30 am:

    Thanks for sharing your solution, it works! I went for launching ant as an entirely separate process in the end, no need to mess around with optional ant tasks and putting the ant-junit.jar file in the right place.

  3. Anthony Chaves wrote on February 21st, 2007 at 9:15 pm:

    I’m glad this solution worked for you Bert. Thanks for visiting and commenting!

  4. Scott Russell wrote on April 20th, 2007 at 1:05 pm:

    I’m running under eclipse and was seeing the same ClassNotFound error.

    Simply specifying a similar to what your build.xml shows above worked for me. So thanks.

    I was actually able to get it to work without having to build a separate jar. The key under eclipse is that ant is run from the src directory so each path var has to be relative to src. i.e.

    Hope this helps someone like Anthony’s build.xml helped me. :-)

  5. Scott Russell wrote on April 20th, 2007 at 1:08 pm:

    sorry, the classpath & property tag examples didn’t show in my previous post.

    …specifying a similar “classpath” to what…

    i.e. [minus the angle brackets]
    property name=”build.dir” value=”../bin”

  6. Malu Cadavid wrote on October 26th, 2007 at 11:51 am:

    You can also use the project tag of the basedir property to specify the path root:

    Then the classpath properties can be defined relative to the basedir

    Cheers

    -Malu

  7. Malu Cadavid wrote on October 26th, 2007 at 11:53 am:

    sorry, same problem as Russell

    project name=”generateXmlData” basedir=”../../”

  8. Tim Brown wrote on November 7th, 2007 at 12:32 pm:

    Actually you don’t have to Jar. Just use path location=root folder.

    I can’t see your build.xml (bad link), but I suspect you’re using a fileset to include all the class files. What you want is to just include the directory *containing* the class files. (i.e. – folder containing com/org/whatever).

    Path location=foo will do that.

    Cheers

  9. Oliver wrote on April 5th, 2009 at 4:29 pm:

    Thanks for your explanation. Although the link to your build has died I was able to reconstruct the my classpath.

    Thanks for the tip. This was a headscratcher. Now everything is fine.