*/
    @CheckReturnValue
    SnapshotHierarchy store(String absolutePath, MetadataSnapshot snapshot, NodeDiffListener diffListener);

    /**
     * Returns a hierarchy without any information at the absolute path.
     */
    @CheckReturnValue
    SnapshotHierarchy invalidate(String absolutePath, NodeDiffListener diffListener);

    /**
     * The empty hierarchy.

    @Override
    public SnapshotHierarchy updateVfsBeforeBuildFinished(SnapshotHierarchy root, int maximumNumberOfWatchedHierarchies, List<File> unsupportedFileSystems) {
        SnapshotHierarchy newRoot = watchableHierarchies.removeUnwatchableContentBeforeBuildFinished(
            root,

    }

    /**
     * Runs a single update on a {@link SnapshotHierarchy} and notifies the currently active listeners after the update.
     */
    protected abstract SnapshotHierarchy updateNotifyingListeners(UpdateFunction updateFunction);

    public interface UpdateFunction {
        /**
         * Runs a single update on a {@link SnapshotHierarchy}, notifying the diffListener about changes.
         *

     *
     * @see FileWatcherRegistry#registerWatchableHierarchy(File, SnapshotHierarchy)
     */
    void registerWatchableHierarchy(File watchableHierarchy, SnapshotHierarchy root);

    /**
     * Updates the watchers after changes to the root.
     *
     * @see FileWatcherRegistry#virtualFileSystemContentsChanged(Collection, Collection, SnapshotHierarchy)
     */

package org.gradle.api.internal.file;

import org.gradle.internal.snapshot.SnapshotHierarchy;
import org.gradle.internal.vfs.impl.AbstractVirtualFileSystem;

public class TestVirtualFileSystem extends AbstractVirtualFileSystem {

    public TestVirtualFileSystem(SnapshotHierarchy root) {
        super(root);
    }

    @Override
    protected SnapshotHierarchy updateNotifyingListeners(UpdateFunction updateFunction) {

import org.gradle.internal.snapshot.SingletonChildMap;
import org.gradle.internal.snapshot.SnapshotHierarchy;
import org.gradle.internal.snapshot.UnknownFileSystemNode;
import org.gradle.internal.snapshot.VfsRelativePath;

import java.util.Optional;
import java.util.stream.Stream;

public class DefaultSnapshotHierarchy implements SnapshotHierarchy {

    private final CaseSensitivity caseSensitivity;
    @VisibleForTesting

    public WatchingNotSupportedVirtualFileSystem(SnapshotHierarchy root) {
        super(root);
    }

    @Override
    protected SnapshotHierarchy updateNotifyingListeners(UpdateFunction updateFunction) {
        return updateFunction.update(SnapshotHierarchy.NodeDiffListener.NOOP);
    }

    @Override
    public boolean afterBuildStarted(

    /**
     * Updates the watchers after changes to the root.
     *
     * @throws WatchingNotSupportedException when the native watchers can't be updated.
     */
    void virtualFileSystemContentsChanged(Collection<FileSystemLocationSnapshot> removedSnapshots, Collection<FileSystemLocationSnapshot> addedSnapshots, SnapshotHierarchy root);

    /**

                return hasSnapshotsToWatch;
            }
        });
    }

    @Override
    public SnapshotHierarchy updateVfsBeforeBuildFinished(SnapshotHierarchy root, int maximumNumberOfWatchedHierarchies, List<File> unsupportedFileSystems) {
        SnapshotHierarchy newRoot = super.updateVfsBeforeBuildFinished(root, maximumNumberOfWatchedHierarchies, unsupportedFileSystems);

package org.gradle.internal.watch.vfs.impl;

import com.google.common.collect.EnumMultiset;
import com.google.common.collect.Multiset;
import org.gradle.internal.file.FileType;
import org.gradle.internal.snapshot.SnapshotHierarchy;
import org.gradle.internal.watch.registry.FileWatcherRegistry;
import org.gradle.internal.watch.vfs.FileSystemWatchingStatistics;

import static org.gradle.internal.snapshot.SnapshotVisitResult.CONTINUE;