How to programmatically call a Maven-task

Question

I'm using Maven in the context of another build-tool (leiningen for Clojure, but this should not matter), and I would like to know how I would call a plugin like dependency:build-classpath programmatically (i.e. via the Maven-API, not via the mvn-command).

Answer 1

The Ant Maven tasks can give you an idea how to do it (DependenciesTask source). Another route may be the PomModuleDescriptorParser used by Ivy.

Answer 2

See how org.apache.maven.plugin.testing.AbstractMojoTestCase from maven-plugin-testing-harness is implemented. Here's a code snippet from some of my tests which may be helpful.

public abstract class JAXBGenerateTest extends AbstractMojoTestCase {

    static {
        System.setProperty("basedir", getBaseDir().getAbsolutePath());
    }

    protected MavenProjectBuilder mavenProjectBuilder;

    protected void setUp() throws Exception {
        super.setUp();

        mavenProjectBuilder = (MavenProjectBuilder) getContainer().lookup(
                MavenProjectBuilder.ROLE);
    }

    protected static File getBaseDir() {...}

    /**
     * Validate the generation of a java files from purchaseorder.xsd.
     * 
     * @throws MojoExecutionException
     */
    public void testExecute() throws Exception {

        final File pom = new File(getBaseDir(),
        "src/test/resources/test-pom.xml");

        final ArtifactRepository localRepository = new DefaultArtifactRepository( "local", 

                new File(getBaseDir(), "target/test-repository").toURI().toURL().toString()             , new DefaultRepositoryLayout());


        final MavenProject mavenProject = mavenProjectBuilder.build(pom, localRepository, null);


        final XJC2Mojo generator = (XJC2Mojo) lookupMojo("generate", pom);
        generator.setProject(mavenProject);
        generator.setLocalRepository(localRepository);
        generator.setSchemaDirectory(new File(getBaseDir(),"src/test/resources/"));
        generator.setSchemaIncludes(new String[] { "*.xsd" });
        generator.setBindingIncludes(new String[] { "*.xjb" });
        generator.setGenerateDirectory(new File(getBaseDir(), "target/test/generated-sources"));
        generator.setVerbose(true);
        generator.setGeneratePackage("unittest");
        generator.setRemoveOldOutput(false);

        generator.execute();
    }

}