src/it/skip-missing-junit-it/custom-build.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="skip-missing-junit-it" default="package" basedir=".">

  <import file="maven-build.xml"/>

  <target name="junit-missing" 
          depends="test-junit-status" 
          if="junit.missing">
    <echo level="error">Skipping tests should also work if JUnit is not present at all.</echo>
    <fail>JUnit not found on class path, cannot run unit tests.</fail>
  </target>

</project>