PITest Hands-on

In this hands-on, we will try applying PITest, a lightweight Java mutation tool, to one of Apache's open source project via the Maven build tool.

PITest

PITest is a Java mutation tool developed by Henry Coles. What distinguishes PITest from other mutation tools is the fact that it was developed by a practicing software engineer with the aim of actually applying mutation testing to real world projects. As such, PITest maintains a relativly simple set of mutation operators, for the sake of efficiency. On the other hand, it comes with plug-in supports with build tools (such as Maven) as well as an excellent report feature.

Instructions

1. You should have Jave8+ runtime environment.
2. We will use the Apache Maven build tool. Install the current version.
3. We will use Apache Commons Lang3 as our target system. Download the current version, and unzip the compressed source files.
4. Inside the lang3 directory, you will find the Maven build congifuration file, named pom.xml. Open it.
5. Find <plugins> tag in pom.xml. Add the following plugin entry inside the <plugins>:

<plugin>
  <groupId>org.pitest</groupId>
  <artifactId>pitest-maven</artifactId>
  <version>1.12.0</version>
  <dependencies>
    <dependency>
      <groupId>org.pitest</groupId>
      <artifactId>pitest-junit5-plugin</artifactId>
      <version>1.1.1</version>
    </dependency>
  </dependencies>
  <configuration>
    <targetClasses>
      <param>org.apache.commons.lang3.compare.*</param>
    </targetClasses>
    <targetTests>
      <param>org.apache.commons.lang3.compare.*</param>
    </targetTests>
  </configuration>
</plugin>

6. Now, execute Maven using the following:

$ mvn test-compile org.pitest:pitest-maven:mutationCoverage

7. You can check the result by looking at target/pit-reports.