pkg/analyzer/test/file_system/file_system_test_support.dart

// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:io';
import 'dart:typed_data';

import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/file_system/physical_file_system.dart';
import 'package:analyzer/source/file_source.dart';
import 'package:analyzer/source/source.dart';
import 'package:path/path.dart' as path;
import 'package:test/test.dart';
import 'package:test_reflective_loader/test_reflective_loader.dart';
import 'package:watcher/watcher.dart' show ChangeType;

final isFile = TypeMatcher<File>();
final isFileSystemException = TypeMatcher<FileSystemException>();
final isFolder = TypeMatcher<Folder>();

final throwsFileSystemException = throwsA(isFileSystemException);

typedef _WatcherChanges = ({
  List<ChangeType> changes,
  Future<void> Function() cancel,
});

abstract class FileSystemTestSupport {
  /// The content used for the file at the [defaultFilePath] if it is created
  /// and no other content is provided.
  String get defaultFileContent;

  /// A path to a file within the [defaultFolderPath] that can be used by tests.
  String get defaultFilePath;

  /// A path to a folder within the [tempPath] that can be used by tests.
  String get defaultFolderPath;

  /// Return `true` if the file system has support for symbolic links.
  /// Windows until recently (Windows 10, 2016) did not have it.
  bool get hasSymbolicLinkSupport;

  /// Return the resource provider to be used by the tests.
  ResourceProvider get provider;

  /// The absolute path to the temporary directory in which all of the tests are
  /// to work.
  String get tempPath;

  /// Return a file accessed through the resource provider. If [exists] is
  /// `true` then the returned file will exist, otherwise it won't. If [content]
  /// is provided then the file will have the given content, otherwise it will
  /// have the [defaultFileContent]. If the file does not exist then the content
  /// is ignored. If a [filePath] is provided, then the file will be located at
  /// that path; otherwise the file will have the [defaultFilePath].
  File getFile({required bool exists, String? content, String? filePath});

  /// Return a folder accessed through the resource provider. If [exists] is
  /// `true` then the returned folder will exist, otherwise it won't. If a
  /// [folderPath] is provided, then the folder will be located at that path;
  /// otherwise the folder will have the [defaultFolderPath].
  Folder getFolder({required bool exists, String? folderPath});

  /// Return a link accessed through the resource provider. If [target] is
  /// supplied then the returned link will exist and point to [target],
  /// otherwise it won't.
  Link getLink({required String linkPath, String? target});

  /// Return a file path composed of the provided parts as defined by the
  /// current path context.
  String join(
    String part1, [
    String? part2,
    String? part3,
    String? part4,
    String? part5,
    String? part6,
  ]) => provider.pathContext.join(part1, part2, part3, part4, part5, part6);

  /// Subscribes to [watcher], waits for it to become ready, and returns
  /// a record containing a list of events received (which updates as events
  /// arrive) and a function to cancel.
  Future<_WatcherChanges> _subscribeToWatcher(ResourceWatcher watcher) async {
    var changes = <ChangeType>[];
    var subscription = watcher.changes.listen(
      (event) => changes.add(event.type),
    );

    await watcher.ready;

    return (changes: changes, cancel: subscription.cancel);
  }

  /// Waits up to [maxDuration] for [condition] to return `true`.
  ///
  /// Throws if condition is not `true` before the time expires.
  Future<void> _waitFor(
    FutureOr<bool> Function() condition, [
    // Set the default max high enough to ensure no flakes on slow bots. We
    // check periodically and will exit early if the condition is met.
    Duration maxDuration = const Duration(seconds: 5),
  ]) async {
    var endTime = DateTime.now().add(maxDuration);
    while (DateTime.now().isBefore(endTime)) {
      if (await condition()) {
        return;
      }
      await pumpEventQueue(times: 1000);
    }
    throw 'Condition was not true within $maxDuration';
  }
}

/// Unlike most test mixins, this mixin defines some abstract test methods.
/// These are tests whose behavior differs between the two implementations of
/// the file system and therefore need to be implemented differently. (They
/// probably shouldn't differ, but they do.) The abstract methods exist so that
/// we cannot forget to implement the tests for each implementation.
mixin FileTestMixin implements FileSystemTestSupport {
  @failingTest
  test_changes() {
    // TODO(brianwilkerson): Implement this.
    fail('Not tested');
  }

  test_copyTo_existing() {
    File file = getFile(exists: true, content: 'contents');
    Folder destination = provider.getFolder(join(tempPath, 'destination'));

    File copy = file.copyTo(destination);
    expect(copy.parent, destination);
    expect(copy.shortName, file.shortName);
    expect(copy.exists, isTrue);
    expect(copy.readAsStringSync(), 'contents');
  }

  test_copyTo_notExisting() {
    File file = getFile(exists: false);
    Folder destination = provider.getFolder(join(tempPath, 'destination'));

    expect(() => file.copyTo(destination), throwsA(isFileSystemException));
  }

  test_createSource() {
    File file = getFile(exists: true);

    Source source = FileSource(file);
    expect(source, isNotNull);
    expect(source.fullName, defaultFilePath);
    expect(source.uri, Uri.file(defaultFilePath));
    expect(source.exists(), isTrue);
    expect(source.contents.data, defaultFileContent);
  }

  test_delete_existing() {
    File file = getFile(exists: true);
    expect(file.exists, isTrue);
    expect(file.parent.getChildren(), contains(file));

    file.delete();
    expect(file.exists, isFalse);
    expect(file.parent.getChildren(), isNot(contains(file)));
  }

  test_delete_notExisting();

  test_equals_beforeAndAfterCreate() {
    File file1 = getFile(exists: false);
    File file2 = getFile(exists: true);

    expect(file1 == file2, isTrue);
  }

  test_equals_differentPaths() {
    File file1 = getFile(exists: true);
    File file2 = getFile(exists: true, filePath: join(tempPath, 'file2.txt'));

    expect(file1 == file2, isFalse);
  }

  test_equals_samePath() {
    File file1 = getFile(exists: true);
    var file2 = provider.getResource(file1.path) as File;

    expect(file1 == file2, isTrue);
  }

  test_exists_existing() {
    File file = getFile(exists: true);

    expect(file.exists, isTrue);
  }

  test_exists_links_existing() {
    if (!hasSymbolicLinkSupport) return;

    var a_path = join(tempPath, 'a.dart');
    var b_path = join(tempPath, 'b.dart');

    getLink(linkPath: b_path, target: a_path);
    getFile(exists: true, filePath: a_path);

    var a = provider.getFile(a_path);
    var b = provider.getFile(b_path);

    expect(a.exists, isTrue);
    expect(b.exists, isTrue);
  }

  test_exists_links_notExisting() {
    if (!hasSymbolicLinkSupport) return;

    var a_path = join(tempPath, 'a.dart');
    var b_path = join(tempPath, 'b.dart');

    getLink(linkPath: b_path, target: a_path);

    var a = provider.getFile(a_path);
    var b = provider.getFile(b_path);

    expect(a.exists, isFalse);
    expect(b.exists, isFalse);
  }

  test_exists_notExisting() {
    File file = getFile(exists: false);

    expect(file.exists, isFalse);
  }

  test_hashCode_samePath() {
    File file1 = getFile(exists: true);
    var file2 = provider.getResource(file1.path) as File;

    expect(file1.hashCode, equals(file2.hashCode));
  }

  test_isOrContains_false() {
    File file = getFile(exists: false);

    expect(file.isOrContains(join(tempPath, 'foo', 'a.dart')), isFalse);
  }

  test_isOrContains_true() {
    File file = getFile(exists: false);

    expect(file.isOrContains(file.path), isTrue);
  }

  test_lengthSync_existing() {
    var file = getFile(exists: true);
    var bytes = Uint8List.fromList([1, 2, 3, 4, 5]);
    file.writeAsBytesSync(bytes);

    expect(file.lengthSync, bytes.length);
  }

  test_lengthSync_notExisting() {
    File file = getFile(exists: false);

    expect(() => file.lengthSync, throwsA(isFileSystemException));
  }

  test_modificationStamp_existing() {
    File file = getFile(exists: true);

    expect(file.modificationStamp, isNonNegative);
  }

  test_modificationStamp_notExisting() {
    File file = getFile(exists: false);

    expect(() => file.modificationStamp, throwsA(isFileSystemException));
  }

  /// Test that we can reuse a [ResourceWatcher] to create a second subscription
  /// and cancel it at a different time.
  test_multipleWatchers_staggeredCancel() async {
    var filePath = path.join(tempPath, 'foo');
    var file = getFile(filePath: filePath, exists: true);

    // On Windows, package:watcher may miss modification events for files that
    // were created just before we started watching (see
    // https://github.com/dart-lang/watcher/issues/159), so add an artificial
    // delay there to ensure we don't miss events until that issue is resolved.
    if (provider is PhysicalResourceProvider && Platform.isWindows) {
      await Future<void>.delayed(const Duration(seconds: 1));
    }

    var resource = provider.getResource(filePath);
    var watcher = resource.watch();

    var watch1 = await _subscribeToWatcher(watcher);
    var watch2 = await _subscribeToWatcher(watcher);
    file.writeAsStringSync('first');
    await _waitFor(
      () => watch1.changes.isNotEmpty && watch2.changes.isNotEmpty,
    );

    // Cancel the second watcher before causing the second event.
    await watch2.cancel();

    file.writeAsStringSync('second');
    await _waitFor(() => watch1.changes.length >= 2);

    await watch1.cancel();

    // Watcher 1 should have both events, and watcher 2 should have only the
    // first one.
    expect(watch1.changes.length, 2);
    expect(watch2.changes.length, 1);
  }

  /// Test that we can reuse a [ResourceWatcher] to create a second subscription
  /// at a different time.
  test_multipleWatchers_staggeredSubscribe() async {
    var filePath = path.join(tempPath, 'foo');
    var file = getFile(filePath: filePath, exists: true);

    // On Windows, package:watcher may miss modification events for files that
    // were created just before we started watching (see
    // https://github.com/dart-lang/watcher/issues/159), so add an artificial
    // delay there to ensure we don't miss events until that issue is resolved.
    if (provider is PhysicalResourceProvider && Platform.isWindows) {
      await Future<void>.delayed(const Duration(seconds: 1));
    }

    var resource = provider.getResource(filePath);
    var watcher = resource.watch();

    var watch1 = await _subscribeToWatcher(watcher);
    file.writeAsStringSync('first');
    await _waitFor(() => watch1.changes.isNotEmpty);

    var watch2 = await _subscribeToWatcher(watcher);
    file.writeAsStringSync('second');
    await _waitFor(() => watch2.changes.isNotEmpty);

    await Future.wait([watch1.cancel(), watch2.cancel()]);

    // Watcher 1 should have both events, and watcher 2 should have only the
    // second.
    expect(watch1.changes.length, 2);
    expect(watch2.changes.length, 1);
  }

  test_parent2() {
    File file = getFile(exists: true);

    var parent = file.parent;
    expect(parent.exists, isTrue);
    expect(parent.path, defaultFolderPath);
  }

  test_path() {
    File file = getFile(exists: false);

    expect(file.path, defaultFilePath);
  }

  test_readAsBytesSync_existing() {
    File file = getFile(exists: true);

    expect(file.readAsBytesSync(), <int>[97]);
  }

  test_readAsBytesSync_notExisting() {
    File file = getFile(exists: false);

    expect(() => file.readAsBytesSync(), throwsA(isFileSystemException));
  }

  test_readAsStringSync_existing() {
    File file = getFile(exists: true);

    expect(file.readAsStringSync(), defaultFileContent);
  }

  test_readAsStringSync_notExisting() {
    File file = getFile(exists: false);

    expect(() => file.readAsStringSync(), throwsA(isFileSystemException));
  }

  test_renameSync_existing() {
    String oldPath = join(tempPath, 'file.txt');
    String newPath = join(tempPath, 'new-file.txt');
    File oldFile = getFile(exists: true, filePath: oldPath);

    File newFile = oldFile.renameSync(newPath);
    expect(oldFile.path, oldPath);
    expect(oldFile.exists, isFalse);
    expect(newFile.path, newPath);
    expect(newFile.exists, isTrue);
    expect(newFile.readAsStringSync(), defaultFileContent);
  }

  test_renameSync_existing_conflictsWithFile() {
    String oldPath = join(tempPath, 'file.txt');
    String newPath = join(tempPath, 'new-file.txt');
    File oldFile = getFile(content: 'old', exists: true, filePath: oldPath);
    File newFile = getFile(content: 'new', exists: true, filePath: newPath);

    oldFile.renameSync(newPath);
    expect(oldFile.path, oldPath);
    expect(oldFile.exists, isFalse);
    expect(newFile.path, newPath);
    expect(newFile.exists, isTrue);
    expect(newFile.readAsStringSync(), 'old');
  }

  test_renameSync_existing_conflictsWithFolder() {
    String oldPath = join(tempPath, 'file.txt');
    String newPath = join(tempPath, 'new-baz');
    File oldFile = getFile(exists: true, filePath: oldPath);
    Folder newFolder = getFolder(exists: true, folderPath: newPath);

    expect(() => oldFile.renameSync(newPath), throwsA(isFileSystemException));
    expect(oldFile.path, oldPath);
    expect(oldFile.exists, isTrue);
    expect(newFolder.path, newPath);
    expect(newFolder.exists, isTrue);
  }

  test_renameSync_notExisting();

  test_resolveSymbolicLinksSync_links_existing() {
    if (!hasSymbolicLinkSupport) return;

    var a_path = join(tempPath, 'aaa', 'a.dart');
    var b_path = join(tempPath, 'bbb', 'b.dart');

    getFile(exists: true, filePath: a_path);
    getLink(linkPath: b_path, target: a_path);

    var resolved = provider.getFile(b_path).resolveSymbolicLinksSync();
    expect(resolved.path, a_path);
  }

  test_resolveSymbolicLinksSync_links_existing2() {
    if (!hasSymbolicLinkSupport) return;

    var a = join(tempPath, 'aaa', 'a.dart');
    var b = join(tempPath, 'bbb', 'b.dart');
    var c = join(tempPath, 'ccc', 'c.dart');

    getFile(exists: true, filePath: a);
    getLink(linkPath: b, target: a);
    getLink(linkPath: c, target: b);

    var resolved = provider.getFile(c).resolveSymbolicLinksSync();
    expect(resolved.path, a);
  }

  test_resolveSymbolicLinksSync_links_notExisting() {
    if (!hasSymbolicLinkSupport) return;

    var a = join(tempPath, 'a.dart');
    var b = join(tempPath, 'b.dart');

    getLink(linkPath: b, target: a);

    expect(() {
      provider.getFile(b).resolveSymbolicLinksSync();
    }, throwsA(isFileSystemException));
  }

  test_resolveSymbolicLinksSync_noLinks_existing() {
    File file = getFile(exists: true);

    expect(file.resolveSymbolicLinksSync(), file);
  }

  test_resolveSymbolicLinksSync_noLinks_notExisting() {
    var path = join(tempPath, 'a.dart');

    expect(() {
      provider.getFile(path).resolveSymbolicLinksSync();
    }, throwsA(isFileSystemException));
  }

  test_shortName() {
    File file = getFile(exists: false);

    expect(file.shortName, 'test.dart');
  }

  test_toString() {
    File file = getFile(exists: false);

    expect(file.toString(), defaultFilePath);
  }

  test_toUri() {
    File file = getFile(exists: true);

    expect(file.toUri(), Uri.file(file.path));
  }

  test_writeAsBytesSync_existing() {
    File file = getFile(exists: true);

    var bytes = Uint8List.fromList([99, 99]);
    file.writeAsBytesSync(bytes);
    expect(file.readAsBytesSync(), bytes);
  }

  test_writeAsBytesSync_notExisting();

  test_writeAsStringSync_existing() {
    File file = getFile(exists: true);

    file.writeAsStringSync('cc');
    expect(file.readAsStringSync(), 'cc');
  }

  test_writeAsStringSync_notExisting();
}

mixin FolderTestMixin implements FileSystemTestSupport {
  test_canonicalizePath_absolute() {
    Folder folder = getFolder(exists: false);
    String path2 = join(tempPath, 'folder2');

    expect(folder.canonicalizePath(path2), equals(path2));
  }

  test_canonicalizePath_absolute_dot() {
    Folder folder = getFolder(exists: false);
    String path2 = join(tempPath, 'folder2');

    expect(
      folder.canonicalizePath(join(path2, '.', 'baz')),
      equals(join(path2, 'baz')),
    );
  }

  test_canonicalizePath_absolute_dotDot() {
    Folder folder = getFolder(exists: false);
    String path2 = join(tempPath, 'folder2');
    String path3 = join(tempPath, 'folder3');

    expect(
      folder.canonicalizePath(join(path2, '..', 'folder3')),
      equals(path3),
    );
  }

  test_canonicalizePath_relative() {
    Folder folder = getFolder(exists: false);

    expect(
      folder.canonicalizePath('baz'),
      equals(join(defaultFolderPath, 'baz')),
    );
  }

  test_canonicalizePath_relative_dot() {
    Folder folder = getFolder(exists: false);

    expect(
      folder.canonicalizePath(join('.', 'baz')),
      equals(join(defaultFolderPath, 'baz')),
    );
  }

  test_canonicalizePath_relative_dotDot() {
    Folder folder = getFolder(exists: false);
    String path2 = join(tempPath, 'folder2');

    expect(folder.canonicalizePath(join('..', 'folder2')), equals(path2));
  }

  @failingTest
  test_changes() {
    // TODO(brianwilkerson): Implement this.
    fail('Not tested');
  }

  test_contains_immediateChild() {
    Folder folder = getFolder(exists: false);

    expect(folder.contains(join(defaultFolderPath, 'aaa.txt')), isTrue);
  }

  test_contains_nestedChild() {
    Folder folder = getFolder(exists: false);

    expect(folder.contains(join(defaultFolderPath, 'aaa', 'bbb.txt')), isTrue);
  }

  test_contains_self() {
    Folder folder = getFolder(exists: false);

    expect(folder.contains(defaultFolderPath), isFalse);
  }

  test_contains_unrelated() {
    Folder folder = getFolder(exists: false);

    expect(folder.contains(join(tempPath, 'baz.txt')), isFalse);
  }

  test_copyTo() {
    Folder source = getFolder(
      exists: true,
      folderPath: join(tempPath, 'source'),
    );
    String sourcePath = source.path;
    Folder subdirectory = getFolder(
      exists: true,
      folderPath: join(sourcePath, 'subdir'),
    );
    String subdirectoryPath = subdirectory.path;
    getFile(
      exists: true,
      content: 'file1',
      filePath: join(sourcePath, 'file1.txt'),
    );
    getFile(
      exists: true,
      content: 'file2',
      filePath: join(subdirectoryPath, 'file2.txt'),
    );
    Folder destination = getFolder(
      exists: true,
      folderPath: join(tempPath, 'destination'),
    );

    Folder copy = source.copyTo(destination);
    expect(copy.parent, destination);
    _verifyStructure(copy, source);
  }

  test_create() {
    Folder folder = getFolder(exists: false);
    expect(folder.exists, isFalse);

    folder.create();
    expect(folder.exists, isTrue);
  }

  test_delete() {
    File file = getFile(
      exists: true,
      filePath: join(defaultFolderPath, 'myFile'),
    );
    var folder = file.parent;
    expect(folder.exists, isTrue);
    expect(file.exists, isTrue);

    folder.delete();
    expect(folder.exists, isFalse);
    expect(file.exists, isFalse);
  }

  test_equals_differentPaths() {
    Folder folder1 = getFolder(
      exists: true,
      folderPath: join(tempPath, 'folder1'),
    );
    Folder folder2 = getFolder(
      exists: true,
      folderPath: join(tempPath, 'folder2'),
    );

    expect(folder1 == folder2, isFalse);
  }

  test_equals_samePath() {
    Folder folder1 = getFolder(exists: false);
    Folder folder2 = getFolder(exists: false);

    expect(folder1 == folder2, isTrue);
  }

  test_exists_links_existing() {
    if (!hasSymbolicLinkSupport) return;

    var foo_path = join(tempPath, 'foo');
    var bar_path = join(tempPath, 'bar');

    getLink(linkPath: bar_path, target: foo_path);
    getFolder(exists: true, folderPath: foo_path);

    var foo = provider.getFolder(foo_path);
    var bar = provider.getFolder(bar_path);

    expect(foo.exists, isTrue);
    expect(bar.exists, isTrue);
  }

  test_exists_links_notExisting() {
    if (!hasSymbolicLinkSupport) return;

    var foo_path = join(tempPath, 'foo');
    var bar_path = join(tempPath, 'bar');

    getLink(linkPath: bar_path, target: foo_path);

    var foo = provider.getFolder(foo_path);
    var bar = provider.getFolder(bar_path);

    expect(foo.exists, isFalse);
    expect(bar.exists, isFalse);
  }

  test_getChild_doesNotExist() {
    Folder folder = getFolder(exists: true);

    var child = folder.getChild('no-such-resource');
    expect(child, isNotNull);
    expect(child.exists, isFalse);
  }

  test_getChild_file() {
    Folder folder = getFolder(exists: true);
    getFile(exists: true, filePath: join(defaultFolderPath, 'myFile'));

    var child = folder.getChild('myFile');
    expect(child, isFile);
    expect(child.exists, isTrue);
  }

  test_getChild_folder() {
    Folder folder = getFolder(exists: true);
    getFolder(exists: true, folderPath: join(folder.path, 'myFolder'));

    var child = folder.getChild('myFolder');
    expect(child, isFolder);
    expect(child.exists, isTrue);
  }

  test_getChildren_doesNotExist() {
    Folder folder = getFolder(exists: true);

    folder = folder.getFolder('no-such-folder');
    expect(() => folder.getChildren(), throwsA(isFileSystemException));
  }

  test_getChildren_exists() {
    Folder folder = getFolder(exists: true);
    // create 2 files and 1 folder
    getFile(exists: true, filePath: join(defaultFolderPath, 'a.txt'));
    getFolder(exists: true, folderPath: join(defaultFolderPath, 'bFolder'));
    getFile(exists: true, filePath: join(defaultFolderPath, 'c.txt'));

    // prepare 3 children
    List<Resource> children = folder.getChildren();
    expect(children, hasLength(3));
    children.sort((a, b) => a.shortName.compareTo(b.shortName));
    // check that each child exists
    for (var child in children) {
      expect(child.exists, true);
    }
    // check names
    expect(children[0].shortName, 'a.txt');
    expect(children[1].shortName, 'bFolder');
    expect(children[2].shortName, 'c.txt');
    // check types
    expect(children[0], isFile);
    expect(children[1], isFolder);
    expect(children[2], isFile);
  }

  test_getChildren_hasLink_file() {
    if (!hasSymbolicLinkSupport) return;

    var a_path = join(tempPath, 'a.dart');
    var b_path = join(tempPath, 'b.dart');

    getLink(linkPath: b_path, target: a_path);
    var a = getFile(exists: true, filePath: a_path);

    var children = provider.getFolder(tempPath).getChildren();
    expect(children, hasLength(2));
    expect(children.map((e) => e.path), unorderedEquals([a_path, b_path]));

    var b = children.singleWhere((e) => e.path == b_path) as File;
    expect(b.resolveSymbolicLinksSync(), a);
  }

  test_getChildren_hasLink_folder() {
    if (!hasSymbolicLinkSupport) return;

    var foo_path = join(tempPath, 'foo');
    var bar_path = join(tempPath, 'bar');

    var foo = getFolder(exists: true, folderPath: foo_path);
    getLink(linkPath: bar_path, target: foo_path);

    var children = provider.getFolder(tempPath).getChildren();
    expect(children, hasLength(2));
    expect(children.map((e) => e.path), unorderedEquals([foo_path, bar_path]));

    var b = children.singleWhere((e) => e.path == bar_path) as Folder;
    expect(b.resolveSymbolicLinksSync(), foo);
  }

  test_getChildren_isLink() {
    if (!hasSymbolicLinkSupport) return;

    var foo_path = join(tempPath, 'foo');
    var bar_path = join(tempPath, 'bar');
    var foo_a_path = join(foo_path, 'a.dart');
    var bar_a_path = join(bar_path, 'a.dart');
    var foo_b_path = join(foo_path, 'b');
    var bar_b_path = join(bar_path, 'b');

    var foo_a = getFile(exists: true, filePath: foo_a_path);
    var foo_b = getFolder(exists: true, folderPath: foo_b_path);
    getLink(linkPath: bar_path, target: foo_path);

    var children = provider.getFolder(bar_path).getChildren();
    expect(children, hasLength(2));
    expect(
      children.map((e) => e.path),
      unorderedEquals([bar_a_path, bar_b_path]),
    );

    var bar_a = children.singleWhere((e) => e.path == bar_a_path) as File;
    expect(bar_a.resolveSymbolicLinksSync(), foo_a);

    var bar_b = children.singleWhere((e) => e.path == bar_b_path) as Folder;
    expect(bar_b.resolveSymbolicLinksSync(), foo_b);
  }

  test_getFile_doesNotExist() {
    Folder folder = getFolder(exists: true);

    File child = folder.getFile('myFile');
    expect(child, isNotNull);
    expect(child.exists, isFalse);
  }

  test_getFile_file() {
    Folder folder = getFolder(exists: true);
    getFile(exists: true, filePath: join(defaultFolderPath, 'myFile'));

    File child = folder.getFile('myFile');
    expect(child, isNotNull);
    expect(child.exists, isTrue);
  }

  test_getFile_folder() {
    Folder folder = getFolder(exists: true);
    getFolder(exists: true, folderPath: join(defaultFolderPath, 'myFolder'));

    File child = folder.getFile('myFolder');
    expect(child, isNotNull);
    expect(child.exists, isFalse);
  }

  test_getFolder_doesNotExist() {
    Folder folder = getFolder(exists: true);

    Folder child = folder.getFolder('myFile');
    expect(child, isNotNull);
    expect(child.exists, isFalse);
  }

  test_getFolder_file() {
    Folder folder = getFolder(exists: true);
    getFile(exists: true, filePath: join(defaultFolderPath, 'myFile'));

    Folder child = folder.getFolder('myFile');
    expect(child, isNotNull);
    expect(child.exists, isFalse);
  }

  test_getFolder_folder() {
    Folder folder = getFolder(exists: true);
    getFolder(exists: true, folderPath: join(defaultFolderPath, 'myFolder'));

    Folder child = folder.getFolder('myFolder');
    expect(child, isNotNull);
    expect(child.exists, isTrue);
  }

  test_hashCode() {
    Folder folder1 = getFolder(exists: false);
    Folder folder2 = getFolder(exists: false);

    expect(folder1.hashCode, folder2.hashCode);
  }

  test_isOrContains_containedFile() {
    Folder folder = getFolder(exists: true);

    expect(folder.isOrContains(join(defaultFolderPath, 'aaa.txt')), isTrue);
  }

  test_isOrContains_deeplyContained() {
    Folder folder = getFolder(exists: true);

    expect(
      folder.isOrContains(join(defaultFolderPath, 'aaa', 'bbb.txt')),
      isTrue,
    );
  }

  test_isOrContains_notContained() {
    Folder folder = getFolder(exists: true);

    expect(folder.isOrContains(join(tempPath, 'baz.txt')), isFalse);
  }

  test_isOrContains_same() {
    Folder folder = getFolder(exists: true);

    expect(folder.isOrContains(defaultFolderPath), isTrue);
  }

  /// Test that we can reuse a [ResourceWatcher] to create a second subscription
  /// and cancel it at a different time.
  test_multipleWatchers_staggeredCancel() async {
    var folderPath = path.join(tempPath, 'foo');
    var fileInFolder = getFile(
      filePath: path.join(folderPath, 'file'),
      exists: true,
    );
    var resource = provider.getResource(folderPath);
    var watcher = resource.watch();

    var watch1 = await _subscribeToWatcher(watcher);
    var watch2 = await _subscribeToWatcher(watcher);
    fileInFolder.writeAsStringSync('first');
    await _waitFor(
      () => watch1.changes.isNotEmpty && watch2.changes.isNotEmpty,
    );

    // Cancel the second watcher before causing the second event.
    await watch2.cancel();

    fileInFolder.writeAsStringSync('second');
    await _waitFor(() => watch1.changes.length >= 2);

    await watch1.cancel();

    // Watcher 1 should have both events, and watcher 2 should have only the
    // first one.
    expect(watch1.changes.length, 2);
    expect(watch2.changes.length, 1);
  }

  /// Test that we can reuse a [ResourceWatcher] to create a second subscription
  /// at a different time.
  test_multipleWatchers_staggeredSubscribe() async {
    var folderPath = path.join(tempPath, 'foo');
    var fileInFolder = getFile(
      filePath: path.join(folderPath, 'file'),
      exists: true,
    );
    var resource = provider.getResource(folderPath);
    var watcher = resource.watch();

    var watch1 = await _subscribeToWatcher(watcher);
    fileInFolder.writeAsStringSync('first');
    await _waitFor(() => watch1.changes.isNotEmpty);

    var watch2 = await _subscribeToWatcher(watcher);
    fileInFolder.writeAsStringSync('second');
    await _waitFor(() => watch2.changes.isNotEmpty);

    await Future.wait([watch1.cancel(), watch2.cancel()]);

    // Watcher 1 should have both events, and watcher 2 should have only the
    // second.
    expect(watch1.changes.length, 2);
    expect(watch2.changes.length, 1);
  }

  test_parent() {
    Folder folder = getFolder(exists: true);

    var parent = folder.parent;
    expect(parent.path, equals(tempPath));
    //
    // Since the OS is in control of where tempPath is, we don't know how far it
    // should be from the root. So just verify that each call to parent results
    // in a folder with a shorter path, and that we reach the root eventually.
    //
    while (true) {
      var grandParent = parent.parent;
      if (grandParent.isRoot) {
        break;
      }
      expect(grandParent.path.length, lessThan(parent.path.length));
      parent = grandParent;
    }
  }

  test_relative_if_contains_immediateChild() {
    Folder folder = getFolder(exists: false);
    expect(
      folder.relativeIfContains(join(defaultFolderPath, 'aaa.txt')),
      'aaa.txt',
    );
  }

  test_relative_if_contains_nestedChild() {
    Folder folder = getFolder(exists: false);
    expect(
      folder.relativeIfContains(join(defaultFolderPath, 'aaa', 'bbb.txt')),
      join('aaa', 'bbb.txt'),
    );
  }

  test_relative_if_contains_os_specificic() {
    Folder folder = getFolder(exists: false);
    // On non-Windows path casing does matter.
    String? expectOnCaseDifferenceImmediateChild;
    String? expectOnCaseDifferenceNestedChild;
    if (provider.pathContext.style.name == path.Style.windows.name) {
      // On Windows path casing doesn't matter.
      expectOnCaseDifferenceImmediateChild = 'aaa.txt';
      expectOnCaseDifferenceNestedChild = join('aaa', 'bbb.txt');
    }

    var caseChangedFolder = defaultFolderPath.toUpperCase();

    // Immediate child.
    expect(
      folder.relativeIfContains(join(caseChangedFolder, 'aaa.txt')),
      expectOnCaseDifferenceImmediateChild,
    );

    // Nested child.
    expect(
      folder.relativeIfContains(join(caseChangedFolder, 'aaa', 'bbb.txt')),
      expectOnCaseDifferenceNestedChild,
    );

    // Self (on Windows).
    expect(folder.relativeIfContains(caseChangedFolder), isNull);

    // Unrelated.
    expect(
      folder.relativeIfContains(join(tempPath.toUpperCase(), 'baz.txt')),
      isNull,
    );
  }

  test_relative_if_contains_self() {
    Folder folder = getFolder(exists: false);
    expect(folder.relativeIfContains(defaultFolderPath), isNull);
  }

  test_relative_if_contains_unrelated() {
    Folder folder = getFolder(exists: false);
    expect(folder.relativeIfContains(join(tempPath, 'baz.txt')), isNull);
  }

  test_resolveSymbolicLinksSync_links_existing() {
    if (!hasSymbolicLinkSupport) return;

    var foo = join(tempPath, 'foo');
    var bar = join(tempPath, 'bar');

    getFolder(exists: true, folderPath: foo);
    getLink(linkPath: bar, target: foo);

    var resolved = provider.getFolder(bar).resolveSymbolicLinksSync();
    expect(resolved.path, foo);
  }

  test_resolveSymbolicLinksSync_links_notExisting() {
    if (!hasSymbolicLinkSupport) return;

    var foo = join(tempPath, 'foo');
    var bar = join(tempPath, 'bar');

    getLink(linkPath: bar, target: foo);

    expect(() {
      provider.getFolder(bar).resolveSymbolicLinksSync();
    }, throwsA(isFileSystemException));
  }

  test_resolveSymbolicLinksSync_noLinks_notExisting() {
    var path = join(tempPath, 'foo');

    expect(() {
      provider.getFolder(path).resolveSymbolicLinksSync();
    }, throwsA(isFileSystemException));
  }

  test_toUri() {
    Folder folder = getFolder(exists: true);

    expect(folder.toUri(), Uri.directory(defaultFolderPath));
  }

  /// Verify that the [copy] has the same name and content as the [source].
  void _verifyStructure(Folder copy, Folder source) {
    expect(copy.shortName, source.shortName);
    Map<String, File> sourceFiles = <String, File>{};
    Map<String, Folder> sourceFolders = <String, Folder>{};
    for (Resource child in source.getChildren()) {
      if (child is File) {
        sourceFiles[child.shortName] = child;
      } else if (child is Folder) {
        sourceFolders[child.shortName] = child;
      } else {
        fail('Unknown class of resource: ${child.runtimeType}');
      }
    }
    Map<String, File> copyFiles = <String, File>{};
    Map<String, Folder> copyFolders = <String, Folder>{};
    for (Resource child in source.getChildren()) {
      if (child is File) {
        copyFiles[child.shortName] = child;
      } else if (child is Folder) {
        copyFolders[child.shortName] = child;
      } else {
        fail('Unknown class of resource: ${child.runtimeType}');
      }
    }
    for (String fileName in sourceFiles.keys) {
      var sourceChild = sourceFiles[fileName]!;
      var copiedChild = copyFiles[fileName];
      if (copiedChild == null) {
        fail('Failed to copy file ${sourceChild.path}');
      }
      expect(
        copiedChild.readAsStringSync(),
        sourceChild.readAsStringSync(),
        reason: 'Incorrectly copied file ${sourceChild.path}',
      );
    }
    for (String fileName in sourceFolders.keys) {
      var sourceChild = sourceFolders[fileName]!;
      var copiedChild = copyFolders[fileName];
      if (copiedChild == null) {
        fail('Failed to copy folder ${sourceChild.path}');
      }
      _verifyStructure(copiedChild, sourceChild);
    }
  }
}

mixin LinkTestMixin implements FileSystemTestSupport {
  test_exists_created() {
    var link = getLink(linkPath: join(tempPath, 'link.dart'))
      ..create(join(tempPath, 'target.dart'));
    expect(link.exists, isTrue);
  }

  test_exists_existing() {
    var link = getLink(
      linkPath: join(tempPath, 'link.dart'),
      target: join(tempPath, 'target.dart'),
    );
    expect(link.exists, isTrue);
  }

  test_exists_notExisting() {
    var link = getLink(linkPath: join(tempPath, 'link.dart'));
    expect(link.exists, isFalse);
  }
}

mixin ResourceProviderTestMixin implements FileSystemTestSupport {
  test_getFile_existing() {
    getFile(exists: true);

    File file = provider.getFile(defaultFilePath);
    expect(file, isNotNull);
    expect(file.path, defaultFilePath);
    expect(file.exists, isTrue);
  }

  test_getFile_notExisting() {
    File file = provider.getFile(defaultFilePath);
    expect(file, isNotNull);
    expect(file.path, defaultFilePath);
    expect(file.exists, isFalse);
  }

  test_getFolder_existing() {
    getFolder(exists: true);

    Folder folder = provider.getFolder(defaultFolderPath);
    expect(folder, isNotNull);
    expect(folder.path, defaultFolderPath);
    expect(folder.exists, isTrue);
  }

  test_getFolder_notExisting() {
    Folder folder = provider.getFolder(defaultFolderPath);
    expect(folder, isNotNull);
    expect(folder.path, defaultFolderPath);
    expect(folder.exists, isFalse);
  }

  test_getResource_file_existing() {
    String filePath = getFile(exists: true).path;

    Resource resource = provider.getResource(filePath);
    expect(resource, isFile);
  }

  test_getResource_folder_existing() {
    String filePath = getFolder(exists: true).path;

    Resource resource = provider.getResource(filePath);
    expect(resource, isFolder);
  }

  test_getResource_notExisting() {
    String resourcePath = getFile(exists: false).path;

    Resource resource = provider.getResource(resourcePath);
    expect(resource, isFile);
  }

  test_getStateLocation_uniqueness() {
    var folderOne = provider.getStateLocation('one')!;
    expect(folderOne, isNotNull);

    var folderTwo = provider.getStateLocation('two')!;
    expect(folderTwo, isNotNull);
    expect(folderTwo, isNot(equals(folderOne)));

    expect(provider.getStateLocation('one'), equals(folderOne));
  }

  test_pathContext() {
    expect(provider.pathContext, path.context);
  }
}