import java.io.File;
import java.util.Collection;
import java.util.List;

/**
 * Updater for hierarchical file watchers.
 *
 * For hierarchical watchers, we can use the registered watchable hierarchies as watched directories.
 * Build root directories are always watchable hierarchies.
 * Watching the build root directories is better since they are less likely to be deleted and

    }

    enum Type {
        CREATED,
        MODIFIED,
        REMOVED,
        INVALIDATED,
        OVERFLOW
    }

    /**
     * Registers a watchable hierarchy.
     *
     * The watcher registry will only watch for changes in watchable hierarchies.
     *
     * @throws WatchingNotSupportedException when the native watchers can't be updated.
     */

        then:
        0 * _
        !vfsHasSnapshotsAt(fileOutsideOfWatchableHierarchies)
    }

    def "retains files in hierarchies ignored for watching"() {
        def watchableHierarchy = file("watchable").createDir()
        def fileOutsideOfWatchableHierarchy = file("outside").file("someFile.txt").createFile()
        def fileInDirectoryIgnoredForWatching = file("cache/some-cache/someFile.txt").createFile()

 * <p>
 * The following terms are worth distinguishing between:
 * </p>
 *
 * <dl>
 *     <dt>file system hierarchy</dt>
 *     <dd>A directory on the file system with all its descendants.</dd>
 *
 *     <dt>watchable hierarchies</dt>
 *     <dd>The list of file system hierarchies Gradle might want to watch if interesting content appears in the VFS for them.

            // Remove previously unwatchable files, since they may become watchable.
            // If we register a watchable hierarchy, then there mustn't be anything in the VFS at that location.
            newRoot = invalidateUnwatchableHierarchies(newRoot, invalidator, oldUnwatchableFiles);
            // Remove current unwatchable files, since they still may be watched.

     */
    boolean afterBuildStarted(WatchMode watchingEnabled, VfsLogging vfsLogging, WatchLogging watchLogging, BuildOperationRunner buildOperationRunner);

    /**
     * Register a watchable hierarchy.
     *
     * Only locations within watchable hierarchies will be watched for changes.
     * This method is first called for the root directory of the root project.

    }

    @Override
    int getIfNonHierarchical() { 0 }

    def "does not watch hierarchy to watch if no snapshot is inside"() {
        def watchableHierarchy = file("watchable").createDir()
        def secondWatchableHierarchy = file("watchable2").createDir()
        def fileInWatchableHierarchy = watchableHierarchy.file("some/path/file.txt").createFile()

        when:

        0 * _
    }

    def "removes content on unsupported file systems at the end of the build"() {
        def watchableHierarchy = file("watchable").createDir()
        def watchableContent = watchableHierarchy.file("some/dir/file.txt").createFile()
        def unsupportedFileSystemMountPoint = watchableHierarchy.file("unsupported")

        0 * _

        watchingVirtualFileSystem.root == nonEmptySnapshotHierarchy
    }

    def "collects hierarchies to watch and notifies the vfs"() {
        def watchableHierarchy = new File("watchable")
        def watcherProbe = new File(watchableHierarchy, ".gradle/watch-probe")
        def anotherWatchableHierarchy = new File("anotherWatchable")

    private final FileChangeListeners fileChangeListeners;
    private final List<File> unsupportedFileSystems = new ArrayList<>();
    private Logger warningLogger = LOGGER;

    /**
     * Watchable hierarchies registered before the {@link FileWatcherRegistry} has been started.
     */
    private final Set<File> watchableHierarchiesRegisteredEarly = new LinkedHashSet<>();

    private FileWatcherRegistry watchRegistry;