@Inject
    ToolchainsBuilder toolchainsBuilder;

    @BeforeEach
    void setup() {
        // create session with any local repo, is redefined anyway below
        RepositorySystemSession rss = new MavenSessionBuilderSupplier(repositorySystem)
                .get()
                .withLocalRepositoryBaseDirectories(new File("target").toPath())
                .build();

public class DefaultSessionTest {

    @Test
    void testRootDirectoryWithNull() {
        RepositorySystemSession rss = new DefaultRepositorySystemSession(h -> false);
        DefaultMavenExecutionRequest mer = new DefaultMavenExecutionRequest();
        MavenSession ms = new MavenSession(null, rss, mer, null);
        DefaultSession session =

            throws InvalidRepositoryException {
        RepositorySystem repositorySystem = rs(c);
        RepositorySystemSession session = rss(c);

        ArtifactRepository repository = repositorySystem.buildArtifactRepository(repo);

        if (session != null) {
            repositorySystem.injectMirror(session, Arrays.asList(repository));