------
 Cloning Projects
 ------
 Paul Gier
 ------
 2008-08-02
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Cloning Projects

  By default the projects will be executed in the same directory where they are found.
  This means that build output will be generated with the project files.  It may be
  helpful to copy the projects to another directory before running them, for example
  <<<target/it>>>.  This will allow <<<mvn clean>>> to remove the output generated
  by all of the test projects.
  
+------------------
<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-invoker-plugin</artifactId>
        <version>${project.version}</version>
        <configuration>
          <projectsDirectory>src/it</projectsDirectory>
          <cloneProjectsTo>\${project.build.directory}/it</cloneProjectsTo>
        </configuration>
        <executions>
          <execution>
            <id>integration-test</id>
            <goals>
              <goal>run</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>
+------------------

  There is another benefit of cloning the projects to a temporary location besides keeping the source tree free of build
  output. When the projects are not cloned, the plugin must use temporary POMs to perform their filtering. In contrast,
  cloning the projects enables the plugin to simply filter the cloned POMs in-place. Since a POM's file name remains
  unchanged this way, the inter-project dependencies expressed in the POMs via <<<\<parent\>>>> and <<<\<module\>>>>
  elements remain intact, too. This in turn allows the plugin to filter all POMs that participate in a forked build
  rather than only the root POM of the execution.

  Last but not least, once the projects have been cloned and filtered by an execution of <<<invoker:run>>>, you can
  browse to a cloned project and manually invoke Maven on it. This can be useful to debug the build.