]))
        then:
        rootsOf(watched) == [parent.absolutePath]
        1 * watchable.stream() >> Stream.of(parent, child, grandchild)
    }

    private static List<String> rootsOf(FileHierarchySet set) {
        def roots = []
        set.visitRoots((root -> roots.add(root)))
        return roots
    }

        def commonDir3 = parent.createDir("common/dir3")

        expect:
        rootsOf(from()) == []
        rootsOf(from(dir1)) == [dir1.absolutePath]
        rootsOf(from(dir1, dir1Child)) == [dir1.absolutePath]
        rootsOf(from(commonDir2)) == [commonDir2.absolutePath]
        rootsOf(from(dir1, commonDir2, commonDir3)) == [dir1.absolutePath, commonDir2.absolutePath, commonDir3.absolutePath]
    }

    public final List<BuildOperationRecord> roots;
    public final Map<Long, BuildOperationRecord> records;

    BuildOperationTree(List<BuildOperationRecord> roots) {
        ImmutableMap.Builder<Long, BuildOperationRecord> records = ImmutableMap.builder();
        for (BuildOperationRecord record : roots) {
            visit(records, record);
        }
        this.roots = BuildOperationRecord.ORDERING.immutableSortedCopy(roots);

    private final FileSystemSnapshot roots;
    private final ImmutableMultimap<String, HashCode> rootHashes;
    private final HashCode strategyConfigurationHash;
    private HashCode hash;

    public static CurrentFileCollectionFingerprint from(FileSystemSnapshot roots, FingerprintingStrategy strategy, @Nullable  FileCollectionFingerprint candidate) {
        if (roots == FileSystemSnapshot.EMPTY) {

func PopulateRefs(schemaOf func(ref string) (*spec.Schema, bool), rootRef string) (*spec.Schema, error) {
	visitedRefs := sets.New[string]()
	rootSchema, ok := schemaOf(rootRef)
	visitedRefs.Insert(rootRef)
	if !ok {
		return nil, fmt.Errorf("internal error: cannot resolve Ref for root schema %q: %w", rootRef, ErrSchemaNotFound)
	}
	return populateRefs(schemaOf, visitedRefs, rootSchema)
}

}

func loadSystemRoots() (*CertPool, error) {
	roots := NewCertPool()
	var bestErr error
	for _, file := range certFiles {
		data, err := os.ReadFile(file)
		if err == nil {
			roots.AppendCertsFromPEM(data)
			return roots, nil
		}
		if bestErr == nil || (os.IsNotExist(bestErr) && !os.IsNotExist(err)) {
			bestErr = err
		}
	}
	if bestErr == nil {
		return roots, nil
	}
	return nil, bestErr

	// keep zoneinfo.zip for tethered iOS builds.
	// For self-hosted iOS builds, the zoneinfo.zip is in GOROOT.
	var roots []string
	if goroot != "" {
		roots = append(roots, goroot+"/lib/time")
	}
	wd, err := syscall.Getwd()
	if err == nil {
		roots = append(roots, wd)
	}
	for _, r := range roots {
		var st syscall.Stat_t
		fd, err := syscall.Open(r, syscall.O_RDONLY, 0)
		if err != nil {
			continue
		}

	},

	// #14: roots can exclude subtrees and that doesn't affect other names.
	{
		roots: []constraintsSpec{
			{
				bad: []string{"dns:.example.com"},
			},
		},
		intermediates: [][]constraintsSpec{
			{
				{},
			},
		},
		leaf: leafSpec{
			sans: []string{"dns:foo.com"},
		},
	},

	// #15: roots exclusions are effective.
	{
		roots: []constraintsSpec{
			{

				firstErr = err
			}
			continue
		}
		for _, fi := range fis {
			data, err := os.ReadFile(directory + "/" + fi.Name())
			if err == nil {
				roots.AppendCertsFromPEM(data)
			}
		}
	}

	if roots.len() > 0 || firstErr == nil {
		return roots, nil
	}

	return nil, firstErr
}

// readUniqueDirectoryEntries is like os.ReadDir but omits
// symlinks that point within the directory.

	drop := make(map[string]bool)
	for _, m := range replace {
		drop[m.Path] = true
	}
	var roots []module.Version
	for _, m := range rs.rootModules {
		if !drop[m.Path] {
			roots = append(roots, m)
		}
	}
	roots = append(roots, replace...)
	gover.ModSort(roots)
	return newRequirements(rs.pruning, roots, rs.direct)
}

// A ConstraintError describes inconsistent constraints in EditBuildList