pkgs/watcher/test/directory_watcher/file_changer.dart - tools.git - Git at Google

 // Copyright (c) 2025, 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:io';
 import 'dart:isolate';
 import 'dart:math';

 import 'package:path/path.dart' as p;
 import 'package:watcher/src/testing.dart';

 import '../utils.dart';

 /// Changes files randomly.
 ///
 /// Writes are done in an isolate so as to not block the watcher code being
 /// tested. Content is modified, files are moved, directories are moved.
 /// Directories include nested directories.
 ///
 /// Most file operations as as fast as they can be, consecutive `sync`
 /// operations, but one of the possible operations is "wait" which waits for
 /// one millisecond.
 ///
 /// A fixed random seed is used so a new `FileChanged` will always perform
 /// the same sequence of operations.
 class FileChanger {
   final String path;

   Random _random = Random(0);
   final List<LogEntry> _messages = [];

   FileChanger(this.path);

   /// Changes files under [path], [times] times.
   ///
   /// Changes are randomized with [seed], pass the same value to get the same
   /// changes.
   ///
   /// Returns a log of the changes made.
   Future<List<LogEntry>> changeFiles({required int times, int? seed}) async {
     _random = Random(seed);
     final result = await Isolate.run(() => _changeFiles(times: times));
     return result;
   }

   /// Changes files under [path], replaying the log in [log].
   ///
   /// Returns a new log of the changes made.
   Future<List<LogEntry>> replayLog(String log) async {
     return await Isolate.run(() => _replayLog(log));
   }

   Future<List<LogEntry>> _changeFiles({required int times}) async {
     _messages.clear();
     for (var i = 0; i != times; ++i) {
       await _changeFilesOnce();
     }
     return _messages.toList();
   }

   Future<void> _changeFilesOnce() async {
     switch (_random.nextInt(9)) {
       // "Create" is three times more likely than "delete" so that the set of
       // files grows over time.
       case 0:
       case 1:
       case 2:
         final filePath = _randomFilePath();
         _ensureParent(filePath);
         final content = _randomContent();
         _log('create,$filePath,${content.length}');
         // `flush` seems to make flaky failures more likely on Windows,
         // presumably by ensuring that different states actually reach the
         // filesystem.
         File(filePath).writeAsStringSync(content, flush: true);

       case 3:
         final existingPath = _randomExistingFilePath();
         if (existingPath == null) return;
         final content = _randomContent();
         _log('modify,$existingPath,${content.length}');
         // `flush` seems to make flaky failures more likely on Windows,
         // presumably by ensuring that different states actually reach the
         // filesystem.
         File(existingPath).writeAsStringSync(content, flush: true);

       case 4:
         final existingPath = _randomExistingFilePath();
         if (existingPath == null) return;
         final filePath = _randomFilePath();
         _ensureParent(filePath);
         _log('move file to new,$existingPath,$filePath');
         File(existingPath).renameSync(filePath);

       case 5:
         final existingPath = _randomExistingFilePath();
         if (existingPath == null) return;
         final existingPath2 = _randomExistingFilePath()!;
         _log('move file over file,$existingPath,$existingPath2');
         // Fails sometimes on Windows, so guard+retry.
         retryForPathAccessException(
             () => File(existingPath).renameSync(existingPath2));

       case 6:
         final existingDirectory = _randomExistingDirectoryPath();
         if (existingDirectory == null) return;
         final newDirectory = _randomDirectoryPath();
         if (Directory(newDirectory).existsSync()) return;
         if (newDirectory.startsWith(existingDirectory)) return;
         _ensureParent(newDirectory);
         _log('move directory to new,$existingDirectory,$newDirectory');
         // Fails sometimes on Windows, so guard+retry.
         retryForPathAccessException(
             () => Directory(existingDirectory).renameSync(newDirectory));

       case 7:
         final existingPath = _randomExistingFilePath();
         if (existingPath == null) return;
         _log('delete,$existingPath');
         File(existingPath).deleteSync();

       case 8:
         _log('wait');
         await Future<void>.delayed(const Duration(milliseconds: 1));
     }
   }

   /// Returns 0-999 spaces.
   String _randomContent() => ' ' * _random.nextInt(1000);

   /// Returns a file in a random path from [_randomDirectoryPath].
   String _randomFilePath() {
     return p.join(_randomDirectoryPath(), _random.nextInt(100000).toString());
   }

   /// Returns a random directory with 0-2 levels of subdirectories.
   String _randomDirectoryPath() {
     var result = path;
     final subdirectoryDepth = _random.nextInt(3);
     for (var i = 0; i != subdirectoryDepth; ++i) {
       // Name path segments as single characters a-j so there is a good chance
       // of collisions that will cause multiple files to be created in one
       // directory.
       result = p.join(result, String.fromCharCode(97 + _random.nextInt(10)));
     }
     return result;
   }

   /// Returns the path to an already-created file, or `null` if none exists.
   String? _randomExistingFilePath() =>
       (Directory(path).listSync(recursive: true).whereType<File>().toList()
             ..sort((a, b) => a.path.compareTo(b.path))
             ..shuffle(_random))
           .firstOrNull
           ?.path;

   /// Returns the path to an already-created directory, or `null` if none
   /// exists.
   String? _randomExistingDirectoryPath() => (Directory(
         path,
       ).listSync(recursive: true).whereType<Directory>().toList()
             ..sort((a, b) => a.path.compareTo(b.path))
             ..shuffle(_random))
           .firstOrNull
           ?.path;

   void _ensureParent(String path) {
     final directory = Directory(p.dirname(path));
     if (!directory.existsSync()) {
       _log('create directory,${directory.path}');
       directory.createSync(recursive: true);
     }
   }

   void _log(String message) {
     // Remove the tmp folder from the message.
     message = message.replaceAll(',$path${Platform.pathSeparator}', ',');
     _messages.add(LogEntry('F $message'));
   }

   Future<List<LogEntry>> _replayLog(String log) async {
     _messages.clear();
     for (var line in log.split('\n')) {
       // Check for and strip off the log prefix for file changer lines.
       if (!line.startsWith('F ')) continue;
       line = line.substring(2);
       // There might be exceptions if the log has been edited so some operations
       // are no longer possible, for example if a file or directory does not
       // exist. Skip the operation and skip logging it so the new log is
       // correct.
       final messagesLength = _messages.length;
       try {
         await _replayLine(line);
       } catch (_) {
         while (_messages.length > messagesLength) {
           _messages.removeLast();
         }
       }
     }
     return _messages.toList();
   }

   Future<void> _replayLine(String line) async {
     final items = line.split(',');
     final action = items[0];
     final parameters = items.skip(1).toList();
     switch (action) {
       case 'create':
         final filePath = p.join(path, parameters[0]);
         final content = ' ' * int.parse(parameters[1]);
         _log('create,$filePath,${content.length}');
         File(filePath).writeAsStringSync(content, flush: true);

       case 'create directory':
         final newDirectory = p.join(path, parameters[0]);
         _log('create directory,$newDirectory');
         Directory(newDirectory).createSync(recursive: true);

       case 'modify':
         final filePath = p.join(path, parameters[0]);
         final content = ' ' * int.parse(parameters[1]);
         _log('modify,$filePath,${content.length}');
         File(filePath).writeAsStringSync(content, flush: true);

       case 'move file to new':
         final existingPath = p.join(path, parameters[0]);
         final filePath = p.join(path, parameters[1]);
         _log('move file to new,$existingPath,$filePath');
         File(existingPath).renameSync(filePath);

       case 'move file over file':
         final existingPath = p.join(path, parameters[0]);
         final existingPath2 = p.join(path, parameters[1]);
         _log('move file over file,$existingPath,$existingPath2');
         retryForPathAccessException(
             () => File(existingPath).renameSync(existingPath2));

       case 'move directory to new':
         final existingDirectory = p.join(path, parameters[0]);
         final newDirectory = p.join(path, parameters[1]);
         _log('move directory to new,$existingDirectory,$newDirectory');
         retryForPathAccessException(
             () => Directory(existingDirectory).renameSync(newDirectory));

       case 'delete':
         final existingPath = p.join(path, parameters[0]);
         _log('delete,$existingPath');
         File(existingPath).deleteSync();

       case 'wait':
         _log('wait');
         await Future<void>.delayed(const Duration(milliseconds: 1));

       default:
         throw ArgumentError('Failed to parse log line: $line');
     }
   }
 }
	// Copyright (c) 2025, 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:io';
	import 'dart:isolate';
	import 'dart:math';

	import 'package:path/path.dart' as p;
	import 'package:watcher/src/testing.dart';

	import '../utils.dart';

	/// Changes files randomly.
	///
	/// Writes are done in an isolate so as to not block the watcher code being
	/// tested. Content is modified, files are moved, directories are moved.
	/// Directories include nested directories.
	///
	/// Most file operations as as fast as they can be, consecutive `sync`
	/// operations, but one of the possible operations is "wait" which waits for
	/// one millisecond.
	///
	/// A fixed random seed is used so a new `FileChanged` will always perform
	/// the same sequence of operations.
	class FileChanger {
	final String path;

	Random _random = Random(0);
	final List<LogEntry> _messages = [];

	FileChanger(this.path);

	/// Changes files under [path], [times] times.
	///
	/// Changes are randomized with [seed], pass the same value to get the same
	/// changes.
	///
	/// Returns a log of the changes made.
	Future<List<LogEntry>> changeFiles({required int times, int? seed}) async {
	_random = Random(seed);
	final result = await Isolate.run(() => _changeFiles(times: times));
	return result;
	}

	/// Changes files under [path], replaying the log in [log].
	///
	/// Returns a new log of the changes made.
	Future<List<LogEntry>> replayLog(String log) async {
	return await Isolate.run(() => _replayLog(log));
	}

	Future<List<LogEntry>> _changeFiles({required int times}) async {
	_messages.clear();
	for (var i = 0; i != times; ++i) {
	await _changeFilesOnce();
	}
	return _messages.toList();
	}

	Future<void> _changeFilesOnce() async {
	switch (_random.nextInt(9)) {
	// "Create" is three times more likely than "delete" so that the set of
	// files grows over time.
	case 0:
	case 1:
	case 2:
	final filePath = _randomFilePath();
	_ensureParent(filePath);
	final content = _randomContent();
	_log('create,$filePath,${content.length}');
	// `flush` seems to make flaky failures more likely on Windows,
	// presumably by ensuring that different states actually reach the
	// filesystem.
	File(filePath).writeAsStringSync(content, flush: true);

	case 3:
	final existingPath = _randomExistingFilePath();
	if (existingPath == null) return;
	final content = _randomContent();
	_log('modify,$existingPath,${content.length}');
	// `flush` seems to make flaky failures more likely on Windows,
	// presumably by ensuring that different states actually reach the
	// filesystem.
	File(existingPath).writeAsStringSync(content, flush: true);

	case 4:
	final existingPath = _randomExistingFilePath();
	if (existingPath == null) return;
	final filePath = _randomFilePath();
	_ensureParent(filePath);
	_log('move file to new,$existingPath,$filePath');
	File(existingPath).renameSync(filePath);

	case 5:
	final existingPath = _randomExistingFilePath();
	if (existingPath == null) return;
	final existingPath2 = _randomExistingFilePath()!;
	_log('move file over file,$existingPath,$existingPath2');
	// Fails sometimes on Windows, so guard+retry.
	retryForPathAccessException(
	() => File(existingPath).renameSync(existingPath2));

	case 6:
	final existingDirectory = _randomExistingDirectoryPath();
	if (existingDirectory == null) return;
	final newDirectory = _randomDirectoryPath();
	if (Directory(newDirectory).existsSync()) return;
	if (newDirectory.startsWith(existingDirectory)) return;
	_ensureParent(newDirectory);
	_log('move directory to new,$existingDirectory,$newDirectory');
	// Fails sometimes on Windows, so guard+retry.
	retryForPathAccessException(
	() => Directory(existingDirectory).renameSync(newDirectory));

	case 7:
	final existingPath = _randomExistingFilePath();
	if (existingPath == null) return;
	_log('delete,$existingPath');
	File(existingPath).deleteSync();

	case 8:
	_log('wait');
	await Future<void>.delayed(const Duration(milliseconds: 1));
	}
	}

	/// Returns 0-999 spaces.
	String _randomContent() => ' ' * _random.nextInt(1000);

	/// Returns a file in a random path from [_randomDirectoryPath].
	String _randomFilePath() {
	return p.join(_randomDirectoryPath(), _random.nextInt(100000).toString());
	}

	/// Returns a random directory with 0-2 levels of subdirectories.
	String _randomDirectoryPath() {
	var result = path;
	final subdirectoryDepth = _random.nextInt(3);
	for (var i = 0; i != subdirectoryDepth; ++i) {
	// Name path segments as single characters a-j so there is a good chance
	// of collisions that will cause multiple files to be created in one
	// directory.
	result = p.join(result, String.fromCharCode(97 + _random.nextInt(10)));
	}
	return result;
	}

	/// Returns the path to an already-created file, or `null` if none exists.
	String? _randomExistingFilePath() =>
	(Directory(path).listSync(recursive: true).whereType<File>().toList()
	..sort((a, b) => a.path.compareTo(b.path))
	..shuffle(_random))
	.firstOrNull
	?.path;

	/// Returns the path to an already-created directory, or `null` if none
	/// exists.
	String? _randomExistingDirectoryPath() => (Directory(
	path,
	).listSync(recursive: true).whereType<Directory>().toList()
	..sort((a, b) => a.path.compareTo(b.path))
	..shuffle(_random))
	.firstOrNull
	?.path;

	void _ensureParent(String path) {
	final directory = Directory(p.dirname(path));
	if (!directory.existsSync()) {
	_log('create directory,${directory.path}');
	directory.createSync(recursive: true);
	}
	}

	void _log(String message) {
	// Remove the tmp folder from the message.
	message = message.replaceAll(',$path${Platform.pathSeparator}', ',');
	_messages.add(LogEntry('F $message'));
	}

	Future<List<LogEntry>> _replayLog(String log) async {
	_messages.clear();
	for (var line in log.split('\n')) {
	// Check for and strip off the log prefix for file changer lines.
	if (!line.startsWith('F ')) continue;
	line = line.substring(2);
	// There might be exceptions if the log has been edited so some operations
	// are no longer possible, for example if a file or directory does not
	// exist. Skip the operation and skip logging it so the new log is
	// correct.
	final messagesLength = _messages.length;
	try {
	await _replayLine(line);
	} catch (_) {
	while (_messages.length > messagesLength) {
	_messages.removeLast();
	}
	}
	}
	return _messages.toList();
	}

	Future<void> _replayLine(String line) async {
	final items = line.split(',');
	final action = items[0];
	final parameters = items.skip(1).toList();
	switch (action) {
	case 'create':
	final filePath = p.join(path, parameters[0]);
	final content = ' ' * int.parse(parameters[1]);
	_log('create,$filePath,${content.length}');
	File(filePath).writeAsStringSync(content, flush: true);

	case 'create directory':
	final newDirectory = p.join(path, parameters[0]);
	_log('create directory,$newDirectory');
	Directory(newDirectory).createSync(recursive: true);

	case 'modify':
	final filePath = p.join(path, parameters[0]);
	final content = ' ' * int.parse(parameters[1]);
	_log('modify,$filePath,${content.length}');
	File(filePath).writeAsStringSync(content, flush: true);

	case 'move file to new':
	final existingPath = p.join(path, parameters[0]);
	final filePath = p.join(path, parameters[1]);
	_log('move file to new,$existingPath,$filePath');
	File(existingPath).renameSync(filePath);

	case 'move file over file':
	final existingPath = p.join(path, parameters[0]);
	final existingPath2 = p.join(path, parameters[1]);
	_log('move file over file,$existingPath,$existingPath2');
	retryForPathAccessException(
	() => File(existingPath).renameSync(existingPath2));

	case 'move directory to new':
	final existingDirectory = p.join(path, parameters[0]);
	final newDirectory = p.join(path, parameters[1]);
	_log('move directory to new,$existingDirectory,$newDirectory');
	retryForPathAccessException(
	() => Directory(existingDirectory).renameSync(newDirectory));

	case 'delete':
	final existingPath = p.join(path, parameters[0]);
	_log('delete,$existingPath');
	File(existingPath).deleteSync();

	case 'wait':
	_log('wait');
	await Future<void>.delayed(const Duration(milliseconds: 1));

	default:
	throw ArgumentError('Failed to parse log line: $line');
	}
	}
	}