checkScopeUpdate(Artifact.SCOPE_RUNTIME, Artifact.SCOPE_SYSTEM, Artifact.SCOPE_SYSTEM);
        checkScopeUpdate(Artifact.SCOPE_RUNTIME, Artifact.SCOPE_TEST, Artifact.SCOPE_RUNTIME);

        /* farthest = system */
        checkScopeUpdate(Artifact.SCOPE_SYSTEM, Artifact.SCOPE_COMPILE, Artifact.SCOPE_COMPILE);
        checkScopeUpdate(Artifact.SCOPE_SYSTEM, Artifact.SCOPE_PROVIDED, Artifact.SCOPE_PROVIDED);

                scopes = Arrays.asList(
                        Artifact.SCOPE_COMPILE, Artifact.SCOPE_SYSTEM, Artifact.SCOPE_PROVIDED, Artifact.SCOPE_RUNTIME);
            } else if (Artifact.SCOPE_RUNTIME_PLUS_SYSTEM.equals(classpath)) {
                scopes = Arrays.asList(Artifact.SCOPE_COMPILE, Artifact.SCOPE_SYSTEM, Artifact.SCOPE_RUNTIME);
            } else if (Artifact.SCOPE_TEST.equals(classpath)) {

    }

    @Provides
    static Session newSession(RepositorySystem system, Lookup lookup) {
        Map<String, String> properties = new HashMap<>();
        // Env variables prefixed with "env."
        System.getenv().forEach((k, v) -> properties.put("env." + k, v));
        // Java System properties
        System.getProperties().forEach((k, v) -> properties.put(k.toString(), v.toString()));

    @Nonnull
    Map<String, String> getUserProperties();

    /**
     * Returns immutable system properties to use for interpolation. The system properties are collected from the
     * runtime environment such as {@link System#getProperties()} and environment variables
     * (prefixed with {@code env.}).
     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

                new File(System.getProperty("basedir", "."), "target/local-repo").getAbsoluteFile());
    }

    public ArtifactRepository createDefaultRemoteRepository() throws InvalidRepositoryException {
        return new MavenArtifactRepository(
                DEFAULT_REMOTE_REPO_ID,
                "file://"
                        + new File(System.getProperty("basedir", "."), "src/test/remote-repo")

            final MavenProject mavenProject,
            Throwable t,
            final long buildStartTime) {
        // record the error and mark the project as failed
        long buildEndTime = System.currentTimeMillis();
        buildContext.getResult().addException(t);
        buildContext.getResult().addBuildSummary(new BuildFailure(mavenProject, buildEndTime - buildStartTime, t));

 * <ul>
 *   <li>missing metadata</li>
 *   <li>version range violations</li>
 *   <li>version circular dependencies</li>
 *   <li>missing artifacts</li>
 *   <li>network/transfer errors</li>
 *   <li>file system errors: permissions</li>
 * </ul>
 *
 * TODO carlos: all these possible has*Exceptions and get*Exceptions methods make the clients too

 * <tr><td><code>basedir</code></td>           <td></td>
 *                                             <td>{@link MavenSession#getExecutionRootDirectory()} or
 *                                                 <code>System.getProperty( "user.dir" )</code> if null</td></tr>
 * <tr><td><code>mojoExecution</code></td>     <td></td>               <td>the actual {@link MojoExecution}</td></tr>

        MojoExecution exec = newMojoExecution();

        MavenSession session = newMavenSession();

        Object result = new PluginParameterExpressionEvaluator(session, exec).evaluate("${plugin}");

        System.out.println("Result: " + result);

        assertSame(
                exec.getMojoDescriptor().getPluginDescriptor(),
                result,
                "${plugin} expression does not return plugin descriptor.");

        return request.getUserProperties();
    }

    /**
     * Gets the system properties to use for interpolation and profile activation. The system properties are collected
     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @return The system properties, never {@code null}.
     */
    public Properties getSystemProperties() {