Add DirectoryWatcher symlink tests.

Author: davidmorgan

pkgs/watcher/test/directory_watcher/shared.dart renamed to pkgs/watcher/test/directory_watcher/file_tests.dart

@@ -1,6 +1,7 @@
 // Copyright (c) 2012, 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' as io;
 import 'dart:isolate';
 
@@ -10,7 +11,7 @@ import 'package:watcher/src/utils.dart';
 
 import '../utils.dart';
 
-void sharedTests() {
+void fileTests() {
   test('does not notify for files that already exist when started', () async {
     // Make some pre-existing files.
     writeFile('a.txt');

pkgs/watcher/test/directory_watcher/link_tests.dart

@@ -0,0 +1,81 @@
+// 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 'package:test/test.dart';
+
+import '../utils.dart';
+
+void linkTests() {
+  test('notifies when a link is added', () async {
+    createDir('targets');
+    createDir('links');
+    writeFile('targets/a.target');
+    await startWatcher(path: 'links');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await expectAddEvent('links/a.link');
+  });
+
+  test(
+      'notifies when a link is replaced with a link to a different target '
+      'with the same contents', () async {
+    createDir('targets');
+    createDir('links');
+    writeFile('targets/a.target');
+    writeFile('targets/b.target');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await startWatcher(path: 'links');
+
+    deleteLink('links/a.link');
+    writeLink(link: 'links/a.link', target: 'targets/b.target');
+
+    await expectModifyEvent('links/a.link');
+  });
+
+  test(
+      'notifies when a link is replaced with a link to a different target '
+      'with different contents', () async {
+    writeFile('targets/a.target', contents: 'a');
+    writeFile('targets/b.target', contents: 'b');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await startWatcher(path: 'links');
+
+    deleteLink('links/a.link');
+    writeLink(link: 'links/a.link', target: 'targets/b.target');
+
+    await expectModifyEvent('links/a.link');
+  });
+
+  test('does not notify when a link target is modified', () async {
+    createDir('targets');
+    createDir('links');
+    writeFile('targets/a.targt');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await startWatcher(path: 'links');
+    writeFile('targets/a.target', contents: 'modified');
+    await expectNoEvents();
+  });
+
+  test('does not notify when a link target is removed', () async {
+    createDir('targets');
+    createDir('links');
+    writeFile('targets/a.target');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await startWatcher(path: 'links');
+    deleteFile('targets/a.target');
+    await expectNoEvents();
+  });
+
+  test('notifies when a link is moved within the watched directory', () async {
+    createDir('targets');
+    createDir('links');
+    writeFile('targets/a.target');
+    writeLink(link: 'links/a.link', target: 'targets/a.target');
+    await startWatcher(path: 'links');
+
+    renameLink('links/a.link', 'links/b.link');
+
+    await inAnyOrder(
+        [isAddEvent('links/b.link'), isRemoveEvent('links/a.link')]);
+  });
+}

pkgs/watcher/test/directory_watcher/linux_test.dart

@@ -10,12 +10,14 @@ import 'package:watcher/src/directory_watcher/linux.dart';
 import 'package:watcher/watcher.dart';
 
 import '../utils.dart';
-import 'shared.dart';
+import 'file_tests.dart';
+import 'link_tests.dart';
 
 void main() {
   watcherFactory = LinuxDirectoryWatcher.new;
 
-  sharedTests();
+  fileTests();
+  linkTests();
 
   test('DirectoryWatcher creates a LinuxDirectoryWatcher on Linux', () {
     expect(DirectoryWatcher('.'), const TypeMatcher<LinuxDirectoryWatcher>());

pkgs/watcher/test/directory_watcher/mac_os_test.dart

@@ -10,12 +10,14 @@ import 'package:watcher/src/directory_watcher/mac_os.dart';
 import 'package:watcher/watcher.dart';
 
 import '../utils.dart';
-import 'shared.dart';
+import 'file_tests.dart';
+import 'link_tests.dart';
 
 void main() {
   watcherFactory = MacOSDirectoryWatcher.new;
 
-  sharedTests();
+  fileTests();
+  linkTests();
 
   test('DirectoryWatcher creates a MacOSDirectoryWatcher on Mac OS', () {
     expect(DirectoryWatcher('.'), const TypeMatcher<MacOSDirectoryWatcher>());

pkgs/watcher/test/directory_watcher/polling_test.dart

@@ -9,14 +9,14 @@ import 'package:test/test.dart';
 import 'package:watcher/watcher.dart';
 
 import '../utils.dart';
-import 'shared.dart';
+import 'file_tests.dart';
 
 void main() {
   // Use a short delay to make the tests run quickly.
   watcherFactory = (dir) => PollingDirectoryWatcher(dir,
       pollingDelay: const Duration(milliseconds: 100));
 
-  sharedTests();
+  fileTests();
 
   test('does not notify if the modification time did not change', () async {
     writeFile('a.txt', contents: 'before');

pkgs/watcher/test/directory_watcher/windows_test.dart

@@ -15,12 +15,14 @@ import 'package:watcher/src/directory_watcher/windows.dart';
 import 'package:watcher/watcher.dart';
 
 import '../utils.dart';
-import 'shared.dart';
+import 'file_tests.dart';
+import 'link_tests.dart';
 
 void main() {
   watcherFactory = WindowsDirectoryWatcher.new;
 
-  group('Shared Tests:', sharedTests);
+  fileTests();
+  linkTests();
 
   test('DirectoryWatcher creates a WindowsDirectoryWatcher on Windows', () {
     expect(DirectoryWatcher('.'), const TypeMatcher<WindowsDirectoryWatcher>());

pkgs/watcher/test/utils.dart

@@ -265,7 +265,7 @@ void writeLink({
     dir.createSync(recursive: true);
   }
 
-  Link(fullPath).createSync(target);
+  Link(fullPath).createSync(p.join(d.sandbox, target));
 
   if (updateModified) {
     link = p.normalize(link);
@@ -281,6 +281,17 @@ void deleteFile(String path) {
   _mockFileModificationTimes.remove(path);
 }
 
+/// Schedules deleting a link in the sandbox at [path].
+///
+/// On Linux a link must be deleted with this method.
+/// TODO(davidmorgan): other platforms? Does this delete link or target?
+/// Check other delete links.
+void deleteLink(String path) {
+  Link(p.join(d.sandbox, path)).deleteSync();
+
+  _mockFileModificationTimes.remove(path);
+}
+
 /// Schedules renaming a file in the sandbox from [from] to [to].
 void renameFile(String from, String to) {
   File(p.join(d.sandbox, from)).renameSync(p.join(d.sandbox, to));