JUNIT Test class in Eclipse - java lang ClassNotFoundException

Question

I m trying to run my junit test  to verify that a properties file loads correctly  but  I get ClassNotFoundException although the class is there and all required libraries are there too   Here it is the error I get    Class not found ConfigurationManagerTest                                                 java lang ClassNotFoundException  ConfigurationManagerTest     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 306      at sun misc Launcher AppClassLoader loadClass Launcher java 268      at java lang ClassLoader loadClass ClassLoader java 251      at org eclipse jdt internal junit runner RemoteTestRunner loadClass RemoteTestRunner java 693      at org eclipse jdt internal junit runner RemoteTestRunner loadClasses RemoteTestRunner java 429      at org eclipse jdt internal junit runner RemoteTestRunner runTests RemoteTestRunner java 452      at org eclipse jdt internal junit runner RemoteTestRunner runTests RemoteTestRunner java 683      at org eclipse jdt internal junit runner RemoteTestRunner run RemoteTestRunner java 390      at org eclipse jdt internal junit runner RemoteTestRunner main RemoteTestRunner java 197    any ideas on how to fix this    Thanks

User · Answer

Another possible problem is a missing builder (it will prevent from your .class file from being built).

Check that your .project file has the following lines

<buildSpec>
  <buildCommand>
    <name>org.eclipse.jdt.core.javabuilder</name>
    <arguments>
    </arguments>
  </buildCommand>
</buildSpec>
<natures>
  <nature>org.eclipse.jdt.core.javanature</nature>
</natures>

User · Answer

The above mentioned solutions didn t work for me   I just restarted my IDE by closing it and reopening it   And then error disappeared and its working fine now

User · Answer

I had this problem and it was kind of tricky to realise what was wrong  The project had a dependency project with some error  which stopped the build from execute  When I remove this dependency problem  the project was built as expected   Ps   I am working on a project that has many compilation errors  because we are porting an application that was converted from Delphi to Java  so I didn t care to the compilation error at the beginning  that s why it took me some time to find out the problem

User · Answer

I received this error because I had recently created a new workspace and my  Installed JREs  were not set up correctly  Make sure in Preferences - gt  Java - gt  Installed JREs  the root folder of your JDK is selected  The default for me in a new workspace was a JRE for some reason

User · Answer

I had the similar problem with my Eclipse Helios which debugging Junits  My problem was little different as i was able to run Junits successfully but when i was getting ClassNotFoundException while debugging the same JUNITs   I have tried all sort of different solutions available in Stackoverflow com and forums elsewhere  but nothing seem to work  After banging my head with these issue for close to two days  finally i figured out the solution to it   If none of the solutions seem to work  just delete the  metadata folder created in your workspace  This would create an additional overhead of importing the projects and all sorts of configuration you have done  but these will surely solve these issue   Hope these helps

User · Answer

There is one more possibility  I had the same problem just now and no one of the solutions here helped  Except removing and recreating of the project - I didn t want to try it  What did help  was to clean the project two times immediately one after another  Clean   build could be repeated any number of times - it won t help  Only clean clean and after that build goes OK   Eclipse 3 6   Of course  you should disable autobuild for that   Edit  This post has got its last plus on 15 11 2017  So  the problem  and the solution  remains actual

User · Answer

You may need to do a combination of the above to resolve this problem  I normally get this error when I do mvn clean install and see a compile error preventing the my tests from fully compiling  Assuming the issues resolved by the above have been dealt with  try clicking Project  Clean  and clean the project which contains the test you want to run  Also make sure Build Automatically is checked

User · Answer

Another way that this can unfold  and just did for me  is if you have a build error that Eclipse doesn t tell you about  If compiling the unit test fails then there is no  class file and you will get the ClassNotFoundException   In my case there was a missing 3rd party jar file  When I ran the test I got a pop-up window that said  Errors exist in required project s    I work with a huge project and I always get that message because some of the source is not available to eclipse  long story   Also it doesn t say what the errors are  So I click  Continue  and then I get the exception   Once I realized what was going on it was easy to fix by adding the missing jar to the classpath under Run -  Debug Configurations     I m not sure how to best detect or prevent this from happening except to be aware of this possibility when something goes wrong and to review your most recent changes for what might have gone wrong

User · Answer

I know this has been already answered a long time ago but the answer didnt fix it for me but  I just removed everything from the sources in the buildpath settings and re-added them

User · Answer

Yet another variation  Somehow  my formerly working test classes appeared to be running from some other location  my edits would not execute when I ran the tests     I found that the output folder for my   project loc src test java files was not what I expected   It had inadvertently been set to   project loc target classes  I set it properly in project properties  Java Build Path  Source tab

User · Answer

I too faced the same exception  none of the solutions over internet helped me out  my project contains multiple modules  My Junit code resides in Web module  And it s referring to client module s code   Finally   I tried   Right click on  Web module  project -- build path--  source tab--  Link  source --  added the src files location  Client module s   Thats it  It worked like a charm  Hope it helps

User · Answer

A variation on Guy s answer above  involving additional builders   Say you have an Ant builder configured    lt buildSpec gt       lt buildCommand gt           lt name gt org eclipse jdt core javabuilder lt  name gt           lt arguments gt           lt  arguments gt       lt  buildCommand gt       lt buildCommand gt           lt name gt org eclipse ui externaltools ExternalToolBuilder lt  name gt           lt arguments gt               lt dictionary gt                   lt key gt LaunchConfigHandle lt  key gt                   lt value gt  amp lt project amp gt   externalToolBuilders myprojectantlaunch launch lt  value gt               lt  dictionary gt           lt  arguments gt       lt  buildCommand gt   lt  buildSpec gt    If the Ant build and Eclipse build have differing output locations  Eclipse may not be able to locate the test class on the classpath   In the case of an Ant builder  also check the configured targets for clean  auto  manual and after-clean builds  to ensure that the target which builds the unit tests is called

User · Answer

In  Package Explorer  view  Right click your test class  then  Build Path    Include   it should be OK

User · Answer

I tried everything mentioned here and in other posts  Some of the solutions that people proffered were    Change the output folder for the test Create a custom builder for the project that would run test-compile from Maven Move the Maven dependencies higher in the Order and Export list in the project build path   There were many  many more but the one that I found to work was as follows  Close the development environment  Delete the jars used by the project from my local Maven repository  Open the IDE  Build the project  Run the test   After hours of beating my head against my keyboard and following suggested solutions  this one worked

User · Answer

Right click the project in the Explorer  Build Path -  Order and Export -  Select JRE System Library  jdk  and click Bottom button

User · Answer

what worked for me is to remove the runconfiguration of the test  Then right click the testclass and click run as junit test    now it recreates a correct run config for me

User · Answer

If you have a maven project try to run   mvn clean compile   and then in eclipse clean  amp  build your project

User · Answer

Assumming you tried everything reasonable  delete target  refresh  clean  rebuild  maven install     and that you realized that Eclipse does not behave reasonable    Now  Check if there is no errors suggesting it can be a plugin  any plugin  that has something to do with tests  In my case    I removed EclEmma  It started working       Spent few hours on trying to guess it

User · Answer

This happened to me when I was dragging and dropping test classes to different packages   I just did the following   Saved the class in a text editor  Deleted the offending class from eclipse project explorer  Re-created the class    Bingo  I can now run the test

User · Answer

Are you sure your test class is in the build folder  You re invoking junit in a separate JVM  fork true  so it s possible that working folder would change during that invocation and with build being relative  that may cause a problem   Run ant from command line  not from Eclipse  with -verbose or -debug switch to see the detailed classpath   working dir junit is being invoked with and post the results back here if you re still can t resolve this issue

User · Answer

ConfigurationManagerTest is not being found on your classpath  Ensure that the ConfigurationManagerTest class file is available on your classpath     It might not exist if it wasn t successfully compiled or if it s being created in a directory that you haven t told the Eclipse project should be on the classpath     Assuming that you ve put your test classes in a separate folder  make sure that it shows up in the  Package Explorer  view  rather than the  Navigator  view      Under the project properties   Java Build Path  and the  Source  tab  you can also see if the source folder is included for building as well as where the  class files are generated

User · Answer

I tried all the answers described here but none worked  but found this thread where slomek solves the problem in a very easy manner  Just go to project -  properties --  java build path  Then move Junit to the top by hitting the up bottom to the right  Then everything compiles just fine

User · Answer

I had this problem  in my case the problem relies in the compilation  I am using maven and test classes didn t compile   I fixed it by doing a maven install  it compiles all the files   also you can check for other reasons  that avoid test to compile like if your  run configurations  is skipping the tests to save time

User · Answer

I add this answer as my solution review from the above     You simply edit the file  project in the main project folder  Use a proper XML Editor otherwise you will get a fatal error from Eclipse that stats you can not open this project  I made my project nature Javaby adding this  lt nature gt org eclipse jdt core javanature lt  nature gt  to  lt natures gt  lt  natures gt   I then added those lines correctly indented  lt buildCommand gt  lt name gt org eclipse jdt core javabuilder lt  name gt  lt arguments gt  lt  arguments gt  lt  buildCommand gt  to  lt buildSpec gt  lt  buildSpec gt   Run as JUnit     Success

User · Answer

Please make sure the output folder in Java Build Path tab set as like below which would determine where the  class file are generated Then clean the project

User · Answer

check properties- java build path -  libraries  there should be no errors  in my case there was errors in the maven  once I put the required jar in the maven repo  it worked fine

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