if (t instanceof RuntimeException || !(t instanceof Exception)) {
            // fail fast on RuntimeExceptions, Errors and "other" Throwables
            // assume these are system errors and further build is meaningless
            buildContext.getReactorBuildStatus().halt();
        } else if (MavenExecutionRequest.REACTOR_FAIL_NEVER.equals(rootSession.getReactorFailureBehavior())) {
            // continue the build

  altogether obvious:

  * Localhost may be unavailable. Therefore, even locally installed
    server processes which work by conversing over a port may fail.

  * Not all "remote" repositories will fail. Specifically, if the remote
    repo uses the file:// protocol, and it doesn't refer to a shared
    filesystem, it will continue to be available.

    @BeforeEach
    void setUp() throws Exception {
        source = new Source();

        projectArtifact = createArtifactSpec("project", "1.0", null);
    }

    @Test
    @Disabled("works, but we don't fail on cycles presently")
    void testCircularDependencyNotIncludingCurrentProject()
            throws ArtifactResolutionException, InvalidVersionSpecificationException {
        ArtifactSpec a = createArtifactSpec("a", "1.0");

        return sb.toString();
    }

    public Artifact find(Artifact artifact) {
        File artifactFile = new File(getBasedir(), pathOf(artifact));

        // We need to set the file here or the resolver will fail with an NPE, not fully equipped to deal
        // with multiple local repository implementations yet.
        artifact.setFile(artifactFile);

        return artifact;
    }

    void testChecksumVerification() throws Exception {
        ArtifactRepositoryPolicy policy = new ArtifactRepositoryPolicy(
                true, ArtifactRepositoryPolicy.UPDATE_POLICY_ALWAYS, ArtifactRepositoryPolicy.CHECKSUM_POLICY_FAIL);

        ArtifactRepository repo = artifactRepositoryFactory.createArtifactRepository(
                "id", "string://url", new ArtifactRepositoryLayoutStub(), policy, policy);

            want to analyze the set of transitive dependencies, in particular during early lifecycle phases where
            full dependency resolution might fail due to projects which haven't been built yet.
          </description>
        </field>
        <field>
          <name>dependencyCollection</name>
          <version>2.0.0+</version>
          <type>String</type>

        projects.add(project2);

        assertThrows(
                DuplicateProjectException.class,
                () -> new ProjectSorter(projects).getSortedProjects(),
                "Duplicate projects should fail");
    }

    @Test
    void testMatchingIdsAndDifferentVersions() throws Exception {
        List<MavenProject> projects = new ArrayList<>();

        legacySupport.setSession(session);
    }

    protected abstract String component();

    /**
     * Return an existing file, not a directory - causes creation to fail.
     *
     * @throws Exception
     */
    protected ArtifactRepository badLocalRepository() throws Exception {
        String path = "target/test-repositories/" + component() + "/bad-local-repository";

import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

class DefaultMavenProjectBuilderTest extends AbstractMavenProjectTestCase {
    @TempDir
    File localRepoDir;

    // only use by reread()
    @TempDir
    Path projectRoot;

    @Override

    // Reactor Failure Mode
    // ----------------------------------------------------------------------

    String REACTOR_FAIL_FAST = "FAIL_FAST";

    String REACTOR_FAIL_AT_END = "FAIL_AT_END";

    String REACTOR_FAIL_NEVER = "FAIL_NEVER";

    // ----------------------------------------------------------------------
    // Reactor Make Mode