Many times you may want to reuse the tests that you have created for a project in another. For example if you have written foo-core and it contains test code in the ${basedir}/src/test/java it would be useful to package up those compiled tests in a JAR and deploy them for general reuse. To do this you would configure the maven-jar-plugin as follows:
<project>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<goals>
<goal>test-jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
In order to install the attached test JAR you simply use the standard install phase by executing the following command:
mvn install
In order to deploy the attached test JAR you simply use the standard deploy phase by executing the following command:
mvn deploy
In order to use the attached test JAR that was created above you simply specify a dependency on the main artifact with a specified type of test-jar:
<project>
...
<dependencies>
<dependency>
<groupId>com.myco.app</groupId>
<artifactId>foo</artifactId>
<version>1.0-SNAPSHOT</version>
<type>test-jar</type>
<scope>test</scope>
</dependency>
</dependencies>
...
</project>
Note that previous editions of this guide suggested to use <classifier>tests</classifier> instead of <type>test-jar</type>. While this currently works for some cases, it does not properly work during a reactor build of the test JAR module and any consumer if a lifecycle phase prior to install is invoked. In such a scenario, Maven will not resolve the test JAR from the output of the reactor build but from the local/remote repository. Apparently, the JAR from the repositories could be outdated or completely missing, causing a build failure (cf. MNG-2045).