Ok I was able to fix this problem.
One of my dependencies had a systemPath attribute with a relative path. So I removed that line of the pom and my tests were successful.
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.4.1</version>
<scope>system</scope>
<systemPath>${basedir}/src/eclipseLink/eclipselink.jar</systemPath> ---> REMOVE THIS LINE
</dependency>