Thursday, December 31, 2009

Continuous Integration of Python Code with Unit Tests and Maven

My main development language is Java, but I also some work in Python for deployment and related tools. Being a big fan of unit testing I write unit tests in Python using PyUnit. Being a big fan of Maven and Continuous Integration, I really want the  Python unit tests to run as part of the build. I wanted to have a solution that met the following criteria:
  • Used commonly available plugins
  • Keep the maven structure of test and src files in the appropriate directories.
  • Have the tests run in the test phase and fail the build when the tests fail.

The simplest approach I came up with to do this was to use the Exec Maven Plugin by adding the following configuration to your (python) project's POM.

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>exec-maven-plugin</artifactId>
  <executions>
   <execution>
    <configuration>
     <executable>python</executable>
     <workingDirectory>src/test/python</workingDirectory>
     <arguments>
      <argument>unitTests.py</argument>
     </arguments>    
     <environmentVariables>
       <PYTHONPATH>../../main/python:$PYTHONPATH</PYTHONPATH>
     </environmentVariables>
    </configuration>
    <id>python-test</id>
    <phase>test</phase>
    <goals>
     <goal>exec</goal>
    </goals>
   </execution>
  </executions>
 </plugin>

This works well enough. Setting the PYTHONPATH environment variable allows your pyUnit tests to find the modules you are building in the project. What's less than ideal is that, unlike other maven plugins, the person running the build needs to have python installed and configured correctly. (You can allow for some variations between environments. And if you have a developer on your project who doesn't use python, and doesn't want to there is a property you can set on the exec plugin to skip the tests, so in the end only those who use python, and the continuous integration server, need the correct things installed.

This may be obvious to some, if not many, but in case anyone is looking for an answer to how to run unit tests as part of of your maven build, I hope that this is helpful.

3 comments:

Anonymous said...

Helpful! Thanks.

chris snow said...

Great post, thank you!

Would you mind sharing your unitTests.py or a cut down version of it? My tests are failing but that isn't failing the build, so it would be good to see how your tests are working.

Steve Berczuk said...

I haven't used this in a while, so it's possible that something may have changed. If the the PYUnit execution returns a non-zero status, the build _should_ fail.