Debugging a maven failsaife selenium build in intellij

Recently I had to debug a set of Selenium tests using the failsafe plugin and the embedded tomcat7 plugin using Intellij Idea

Usually you can just click on IDE's the debug button and Intellij will take care to launch the build and attach a debugger to the appropriate debug port:

However this time it wasn't working I had 2 issues with my build :

  1. My breakpoints where completely ignored
  2. The maven build just kept waiting without exiting the project even once the integration tests where finished

So I looked into the possible XML configuration tags for the failsafe plugin and thought that the <debugForkedProcess>true</debugForkedProcess> would be my salvation however I was wrong...

So what's happening here ?

By default, maven runs your tests in a separate ("forked") process. So when you set this property to true, the tests will automatically pause and await a remote debugger on port 5005

However this was not going happen since when you click on the IDE's debug button Intellij will execute a java debugging command similar to this :

java -agentlib:jdwp=transport=dt_socket,address=,suspend=y,server=n -Dmaven.home=C:\dev\bin\maven -Dclassworlds.conf=C:\dev\bin\maven\bin\m2.conf -Dfile.encoding=UTF-8 -classpath "C:\dev\bin\maven\boot\plexus-classworlds-2.4.2.jar;C:\dev\ide\intellij\lib\idea_rt.jar" org.codehaus.classworlds.Launcher --errors --fail-fast --strict-checksums clean verify -P selenium
Connected to the target VM, address: '', transport: 'socket'

Then the failsafe process will start and pause the tests waiting for a debbuger to attach to the 5005

 T E S T S
Listening for transport dt_socket at address: 5005

But as mentioned earlier this will not happen, because Intellij is listening on another port

Upon reading the plugin documentation over here I realized that you can change all of these configuration properties. However I kept reading the plugin documentation and found another promising configuration option <forkMode>true</forkMode>

According to the documentation the forkMode is an option to specify the forking mode. Can be "never", "once" or "always". "none" and "pertest" are also accepted for backwards compatibility. "always" forks for each test-class.

Since in our case we need to attach a debugger to a single thread in order to have our debugger to be called when hitting a break-point we will set this option to never

Now hit again the debug button in your IDE and normally Intellij should be summoned when your break-point is reached

Below is a sample maven configuration excerpt with the configuration for the failsafe plugin



as usual the full code for this application can be found over at my github account

the tests get executed when running the following maven goal :

mvn clean verify -Pselenium

a few tips for the road :

  • Remember to use the suffix IT on your selenium test classes (e.g: otherwise you will have to configure the surefire plugin to ignore them
  • If like me you're running your selenium tests in a self contained mode (i.e : starting the application server, deploying the app, running the tests, stopping the server) remember to configure your server to fork to another process, otherwise the server running process will be started in a blocking mode


  1. Hi Ulises, nice write up, but also you can of course go the way you go, but then you are not debugging what was actually running when the problem occurred.
    When the process is waiting on port 5005 you can simply attach your debugger to that port using a Remote debug configuration (works in Eclipse and IntelliJ).
    Cheers, Chris

    1. Hi,
      Thanks for the input.
      Quick question though when you say "attach your debugger" you mean using Intellij or Eclipse to do Remote debbuging ?




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