Getting Emma to work with Ant can be difficult by only looking at the Emma Documentation. I have written guide in hopes to help those of you wanting to use Emma for code coverage in Ant (along with JUnit). Below I have outlined below some simple steps which you can follow to get Emma, Ant and JUnit to play nicely with each other:

Downloading Emma

First, you will need to download Emma from: http://sourceforge.net/projects/emma/files/emma-release/

The file you should download should be the one that ends with -lib.zip: e.g. emma-2.0.5312-lib.zip. Unzip this file and you fill find two jars inside: emma.jar and emma_ant.jar.

Using Emma in Ant+JUnit

The very first thing you will need to do is to add the taskdef for emma:

<path id="emma.lib">
    <pathelement location="${ant.lib.dir}/emma.jar" />
    <pathelement location="${ant.lib.dir}/emma_ant.jar" />
</path>
<taskdef resource="emma_ant.properties" classpathref="emma.lib" />

This will allow you to use <emma> tags. Next, we need to “instrument” the files which we want to see coverage for. To instrument classes, see below:

<emma>
    <instr instrpath="${classes.dir}" metadatafile="${report.test.dir}/coverage.em" mode="overwrite" merge="true"/>
</emma>

This is the easiest way to instrument classes:

• instrpath: the path/directory which contains the java class files to be instrumented
• metadatafile: this file should be of the form *.em
• mode=”overwrite”: this will overwrite the existing class files with the instrumented class files
• merge=”true”: this specifies whether the metadatafile should be merged or not

<junit printsummary="yes" haltonfailure="no" fork="yes">
    <jvmarg value="-Demma.coverage.out.file=${report.test.dir}/coverage.ec" />
    <jvmarg value="-Demma.coverage.out.merge=true" />
    ... Regular Ant JUnit Test stuff here ...
</junit>

This will generate *.ec files when you run your JUnit tests and when combined with the previous *.em files will allow Emma to generate the coverage report.

To generate a sample coverage report, use the code below:

<emma>
    <report>
        <infileset dir="${report.test.dir}" includes="*.em, *.ec" />
        <xml outfile="${report.test.dir}/coverage.xml" />
        <txt outfile="${report.test.dir}/coverage.txt" />
    </report>
</emma>

Note: both the *.ec and *.em are required in order for emma to generate a proper coverage report.

The coverage reports will be output in ${report.test.dir}/coverage.xml and coverage.txt. The generated XML file here is compatible for use with Hudson/Jenkins Continuous Integration server after installing the Emma plugin.