If you are using maven to build your projects , then you might have found an out of memory condition in your tests.  Well, setting the MAVEN_OPTS variable with JVM specific options will help with this.

Example:

MAVEN_OPTS=-Xmx1024

Depending on what environment you are in, you will need to set this variable.

This will give the JVM more 1024 megs to work with and you can customize the number to fit your needs.