proposal/sandbox/antlib/src/testcases/case.xml

<?xml version="1.0"?>

<project name="case-test" default="test" basedir=".">

  <property name="value" value="task.xml" />

  <target name="init">
    <taskdef name="antlib" classname="org.apache.tools.ant.taskdefs.Antlib" />
    <antlib file="../../build/case_contrib.jar" />
  </target>

  <target name="test" depends="init,case,test1,test2,test3">
   <echo message="Value=${value}" />
  </target>

  <target name="case" >
    <case property="value" >
      <when value="task.xml" property="value.xml" />
    </case>
    <case property="location" >
      <when value="loc" property="location.fail" />
      <when value="" property="location.fail" />
      <else property="location.unset" />
    </case>
  </target>

  <target name="test1" if="value.xml">
   <echo message="Value equals to itself" />
  </target>

  <target name="test2" if="location.fail">
   <fail message="Location passed" />
  </target>

  <target name="test3" if="location.unset">
   <echo message="Location does not exists" />
  </target>

</project>