How to configure JPA for testing in Maven

Question

Is there a way to set up a second persistence.xml file in a Maven project such that it is used for testing instead of the normal one that is used for deployment?

I tried putting a persistence.xml into src/test/resources/META-INF, which gets copied into target/test-classes/META-INF, but it seems target/classes/META-INF (the copy from the src/main/resources) gets preferred, despite mvn -X test listing the classpath entries in the right order:

[DEBUG] Test Classpath :
[DEBUG]   /home/uqpbecke/dev/NetBeansProjects/UserManager/target/test-classes
[DEBUG]   /home/uqpbecke/dev/NetBeansProjects/UserManager/target/classes
[DEBUG]   /home/uqpbecke/.m2/repository/junit/junit/4.5/junit-4.5.jar
...

I would like to be able to run tests against a simple hsqldb configuration without having to change the deployment version of the JPA configuration, ideally straight after project checkout without any need for local tweaking.

Answer 1

The following will work for Maven 2.1+ (prior to that there wasn't a phase between test and package that you could bind an execution to).

You can use the maven-antrun-plugin to replace the persistence.xml with the test version for the duration of the tests, then restore the proper version before the project is packaged.

This example assumes the production version is src/main/resources/META-INF/persistence.xml and the test version is src/test/resources/META-INF/persistence.xml, so they will be copied to target/classes/META-INF and target/test-classes/META-INF respectively.

It would be more elegant to encapsulate this into a mojo, but as you're only copying a file, it seems like overkill.

<plugin>
  <artifactId>maven-antrun-plugin</artifactId>
  <version>1.3</version>
  <executions>
    <execution>
      <id>copy-test-persistence</id>
      <phase>process-test-resources</phase>
      <configuration>
        <tasks>
          <!--backup the "proper" persistence.xml-->
          <copy file="${project.build.outputDirectory}/META-INF/persistence.xml" tofile="${project.build.outputDirectory}/META-INF/persistence.xml.proper"/>
          <!--replace the "proper" persistence.xml with the "test" version-->
          <copy file="${project.build.testOutputDirectory}/META-INF/persistence.xml" tofile="${project.build.outputDirectory}/META-INF/persistence.xml"/>
        </tasks>
      </configuration>
      <goals>
        <goal>run</goal>
      </goals>
    </execution>
    <execution>
      <id>restore-persistence</id>
      <phase>prepare-package</phase>
      <configuration>
        <tasks>
          <!--restore the "proper" persistence.xml-->
          <copy file="${project.build.outputDirectory}/META-INF/persistence.xml.proper" tofile="${project.build.outputDirectory}/META-INF/persistence.xml"/>
        </tasks>
      </configuration>
      <goals>
        <goal>run</goal>
      </goals>
    </execution>
  </executions>
</plugin>