KSB's Java, Ant, JUnit, CruiseControl 'Hello, world' example

Hello.java: Note that it is in the hello package, in the src directory.

$ pwd
/home/ksb/hello
$ mkdir -p src/hello
$ cat src/hello/Hello.java
package hello;

public class Hello {

    public String greet() {
        return "Hello, world";
    }

    public static void main(String[] args) {
        Hello h = new Hello();
        System.out.println(h.greet());
    }
}

(This could be simpler but the greet method is used later when testing with JUnit.) To compile and run:

$ javac src/hello/Hello.java
$ java -cp src hello.Hello
Hello, world

Now write a build.xml file:

$ cat build.xml
<project name="hello" default="dist" basedir=".">
  <description>KSB's ant 'Hello, world' build.xml example</description>

  <property name="src.dir"   value="src"/>
  <property name="build.dir" value="build"/>
  <property name="dist.dir"  value="dist"/>

  <target name="init">
    <mkdir dir="${build.dir}"/>
    <mkdir dir="${dist.dir}"/>
  </target>

  <target name="build" depends="init" description="build everything under ${src.dir}" >
    <javac srcdir="${src.dir}" destdir="${build.dir}"/>
  </target>

  <target name="dist" depends="build" description="generate the distribution" >
    <jar jarfile="${dist.dir}/hello.jar" basedir="${build.dir}">
      <manifest>
        <attribute name="Main-Class" value="hello.Hello"/>
      </manifest>
    </jar>
  </target>

  <target name="run" depends="dist">
    <java jar="${dist.dir}/hello.jar" fork="true" />
  </target>

  <target name="clean" description="clean up" >
    <delete dir="${build.dir}"/>
    <delete dir="${dist.dir}"/>
  </target>
</project>

Note that this not only compiles with the javac task but also creates a jar file with the jar task. There is also a run target using the java task for executing the jar file.

$ ant
Buildfile: build.xml

init:
    [mkdir] Created dir: /home/ksb/hello/build
    [mkdir] Created dir: /home/ksb/hello/dist

build:
    [javac] Compiling 2 source files to /home/ksb/hello/build

dist:
      [jar] Building jar: /home/ksb/hello/dist/hello.jar

BUILD SUCCESSFUL
Total time: 2 seconds

Because we now have a jar file, created with the manifest target, we can now run the program with the java -jar flag:

$ java -jar dist/hello.jar
Hello, world

Or use the run target:

$ ant run
Buildfile: build.xml

init:

build:

dist:

run:
     [java] Hello, world

BUILD SUCCESSFUL
Total time: 1 second

First create a unit test: TestHello.java. I'm putting this in the same dir as Hello.java (so it will be compiled along with Hello.java), though it could live somewhere else.

$ cat src/hello/TestHello.java
package hello;

import junit.framework.TestCase;

public class TestHello extends TestCase {

    public void testHello()
    {
        Hello h = new Hello();
        assertEquals(h.greet(), "Hello, world");
    }
}

Now add the JUnit parts to the build.xml file, which now looks like (modified parts in bold):

$ cat build.xml
<project name="hello" default="dist" basedir=".">
  <description>KSB's ant 'Hello, world' build.xml example</description>

  <property name="src.dir"   value="src"/>
  <property name="build.dir" value="build"/>
  <property name="dist.dir"  value="dist"/>
  <property name="junit.dir" value="junit-results"/>

  <property name="junit.jar" location="/usr/local/share/java/classes/junit.jar"/>
  <property name="test.class" value="hello.TestHello"/>

  <path id="classpath">
    <pathelement location="${build.dir}" />
    <pathelement location="${junit.jar}" />
  </path>

  <target name="init">
    <mkdir dir="${build.dir}"/>
    <mkdir dir="${dist.dir}"/>
    <mkdir dir="${junit.dir}"/>
  </target>

  <target name="build" depends="init" description="build everything under ${src.dir}" >
    <javac srcdir="${src.dir}" destdir="${build.dir}">
      <classpath refid="classpath"/>
    </javac>
  </target>

  <target name="test" depends="build" description="unit test" >
    <junit errorProperty="test.failed" failureProperty="test.failed">
      <test name="${test.class}" todir="${junit.dir}" />
      <formatter type="brief" usefile="false" />
      <formatter type="xml" />
      <classpath refid="classpath" />
    </junit>
    <fail message="Tests failed: check test reports." if="test.failed" />
  </target>

  <target name="dist" depends="build" description="generate the distribution" >
    <jar jarfile="${dist.dir}/hello.jar" basedir="${build.dir}">
      <manifest>
        <attribute name="Main-Class" value="hello.Hello"/>
      </manifest>
    </jar>
  </target>

  <target name="run" depends="dist">
    <java jar="${dist.dir}/hello.jar" fork="true" />
  </target>

  <target name="clean" description="clean up" >
    <delete dir="${build.dir}"/>
    <delete dir="${dist.dir}"/>
    <delete dir="${junit.dir}"/>
  </target>
</project>

This adds the test target using the junit task and directs xml formatted output of JUnit into a junit-results dir which will later be read by CruiseControl.

Before you will be able to run the new test target, junit.jar must be available to ant in order to understand the junit task. This can be done by either adding it to your $CLASSPATH (before ant is run) or make junit.jar appear in ant's lib dir. I've done the latter via a symlink by making /usr/local/ant/lib/junit.jar -> /usr/local/share/java/classes/junit.jar.

So, now using the new test target:

$ ant test
Buildfile: build.xml

init:

build:
    [javac] Compiling 1 source file to /home/ksb/hello/build

test:
    [junit] Testsuite: hello.TestHello
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.006 sec


BUILD SUCCESSFUL
Total time: 2 seconds

Modify Hello.java to break the test and run ant test again to convince yourself that it is indeed testing the class.

Note also that there is now a junit-results/TEST-hello.TestHello.xml file holding the results of JUnit in xml.