Ошибка теста при компиляции

<?xml version="1.0" encoding="UTF-8"?>
<project name="lab4" default="all" >
<property name="src" value="src"/>
<property name="bin" value="bin"/>
<property name="doc" value="doc"/>
<property name="dist" value="dist"/>
<property name="test" value="test"/>
<property name="test.src" value="${test}/src"/>
<property name="test.bin" value="${test}/bin"/>
<property name="dist.jar" value="${dist}/lab4.jar"/>
<property name="junit" value="test/lib/junit-4.10.jar"/>
<target name="mkdirs" description="Создаем каталоги">
<mkdir dir="${bin}"/>
<mkdir dir="${doc}"/>
<mkdir dir="${dist}"/>
<mkdir dir="${test.bin}"/>
</target>
<target name="compile" description="Компиляция проекта" depends="clean,mkdirs">
<echo>Компилируем...</echo>
<javac destdir="${bin}" includeantruntime="false">
<src path="${src}"/>
</javac>
<javac destdir="${test.bin}" includeantruntime="false">
<src path="${test.src}"/>
<classpath>
<pathelement location="${junit}"/>
<pathelement location="${bin}"/>
</classpath>
</javac>
</target>
<target name="test" depends="compile">
<junit haltonerror="yes" printsummary="yes" haltonfailure="yes">
<classpath>
<pathelement location="${junit}"/>
<pathelement location="${test.bin}"/>
<pathelement location="${bin}"/>
</classpath>
<formatter type="plain" usefile="false" />
<batchtest fork="yes">
<fileset dir="${test.bin}" />
</batchtest>
</junit>
</target>
<target name="all" description="Очистить и построить проект" depends="test">
<echo>Сборка проекта...</echo>
<javadoc sourcepath="src" destdir="doc" />
<jar destfile="${dist.jar}" basedir="${bin}">
<manifest>
<attribute name="Main-Class" value="ru.agrytskov.lab4.Lab4"/>
</manifest>
</jar>
</target>
<target name="clean" description="Очистка">
<echo>Удаление каталогов</echo>
<delete dir="${bin}"/>
<delete dir="${doc}"/>
<delete dir="${dist}"/>
<delete dir="${test.bin}"/>
</target>
</project>

aleks@ubuntu:~/Test/Lab4$ ant
Buildfile: build.xml
 
clean:
     [echo] Удаление каталогов
   [delete] Deleting directory /home/aleks/Test/Lab4/bin
   [delete] Deleting directory /home/aleks/Test/Lab4/doc
   [delete] Deleting directory /home/aleks/Test/Lab4/dist
   [delete] Deleting directory /home/aleks/Test/Lab4/test/bin
 
mkdirs:
    [mkdir] Created dir: /home/aleks/Test/Lab4/bin
    [mkdir] Created dir: /home/aleks/Test/Lab4/doc
    [mkdir] Created dir: /home/aleks/Test/Lab4/dist
    [mkdir] Created dir: /home/aleks/Test/Lab4/test/bin
 
compile:
     [echo] Компилируем...
    [javac] Compiling 9 source files to /home/aleks/Test/Lab4/bin
    [javac] Compiling 4 source files to /home/aleks/Test/Lab4/test/bin
 
test:
 
BUILD FAILED
/home/aleks/Test/Lab4/build.xml:32: Problem: failed to create task or type junit
Cause: the class org.apache.tools.ant.taskdefs.optional.junit.JUnitTask was not found.
        This looks like one of Ant's optional components.
Action: Check that the appropriate optional JAR exists in
        -/usr/share/ant/lib
        -/home/aleks/.ant/lib
        -a directory added on the command line with the -lib argument
 
Do not panic, this is a common problem.
The commonest cause is a missing JAR.
 
This is not a bug; it is a configuration problem
 
 
Total time: 1 second