Question

Is it possible to tell Maven2 to execute every jUnit test in new JVM instance (fork) in serial mode, i.e. one by one.

Answer 1

You have to fork the JVM like explained here

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <version>2.9</version>
  <configuration>
    <forkMode>always</forkMode>
  </configuration>
</plugin>

It should also be possible by just declaring a Sytem property

mvn -DforkMode=always test

As described in the documentation: “always” forks for each test-class. I do not know if the “pertest” setting will fork for each test.

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Thanks to @Djebel for pointing out that forkMode is deprecated now. There is a detailed documentation on “Fork Options and Parallel Test Execution” and how to use the new parameters forkCount and reuseForks and that also includes the following migration tips:

Old Setting                         New Setting
forkMode=once (default)             forkCount=1 (default), reuseForks=true (default)
forkMode=always                     forkCount=1 (default), reuseForks=false
forkMode=never                      forkCount=0
forkMode=perthread, threadCount=N   forkCount=N, (reuseForks=false, if you did not had that one set)