Use the MacOS directory watcher on Windows too.

[davidmorgan]

(I guess dart-ecosystem-team was added to the review due to the min SDK version bump and corresponding test workflow change, hi!)

The MacOS directory watcher is fundamentally the same as the Windows one: both watch the root recursively and need to poll the filesystem to learn more about events. It turns out that it can work for both :) with some Windows-specific fixes patched in.

Remove the Windows watcher code, use the Mac one, adapt it as needed.

I didn't rename the Mac watcher files as that would make the diffs hard to read, will do that in a follow-up.

• Add support for logging to the Windows watcher when it runs in an isolate, it's hard to debug issues otherwise :)
• Remove utils.dart, remove a few things to the one place they are used and event batching code to its own file.
• Move event batching code into event_batching.dart and add a test. Add buffering by path version that's equivalent to what the Windows watcher was doing, except that it checks all buffered events via a single timer instead of maintaining+resetting one timer per path.
• Make unix_paths support Windows path separators too, rename to paths. Add test coverage around relative paths / filesystem roots to guard against this breaking something Windows-specific.
• Add test coverage around case-insensitive file systems. This shows up several issues on Windows+Mac, but they are existing issues not new to this PR, so leave them as-is for now.
• Use the fake_async package to test event batching with buffering by path, this introduces a min SDK version of 3.4 so increase the min SDK version.
• PathSet is no longer used, replaced by the nested DirectoryTree instances in the combined Mac+Windows watcher, remove it + test.
• Remove Windows-specific tests that were targeted at the old Windows implementation. These robustness tests are anyway well covered by the newer e2e tests.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:bazel_worker	1.1.5	already published at pub.dev
package:benchmark_harness	2.4.0	already published at pub.dev
package:boolean_selector	2.1.2	already published at pub.dev
package:browser_launcher	1.1.3	already published at pub.dev
package:cli_config	0.2.1-wip	WIP (no publish necessary)
package:cli_util	0.5.0-wip	WIP (no publish necessary)
package:clock	1.1.3-wip	WIP (no publish necessary)
package:code_builder	4.11.1-wip	WIP (no publish necessary)
package:coverage	1.15.0	already published at pub.dev
package:csslib	1.0.2	already published at pub.dev
package:extension_discovery	2.1.0	already published at pub.dev
package:file	7.0.2-wip	WIP (no publish necessary)
package:file_testing	3.1.0-wip	WIP (no publish necessary)
package:glob	2.1.3	already published at pub.dev
package:graphs	2.3.3-wip	WIP (no publish necessary)
package:html	0.15.7-wip	WIP (no publish necessary)
package:io	1.1.0-wip	WIP (no publish necessary)
package:json_rpc_2	4.1.0-wip	WIP (no publish necessary)
package:markdown	7.3.1-wip	WIP (no publish necessary)
package:mime	2.1.0-wip	WIP (no publish necessary)
package:oauth2	2.0.5	already published at pub.dev
package:package_config	2.3.0-wip	WIP (no publish necessary)
package:pool	1.5.2	already published at pub.dev
package:process	5.0.5	already published at pub.dev
package:pub_semver	2.2.0	already published at pub.dev
package:pubspec_parse	1.5.1-wip	WIP (no publish necessary)
package:source_map_stack_trace	2.1.3-wip	WIP (no publish necessary)
package:source_maps	0.10.14-wip	WIP (no publish necessary)
package:source_span	1.10.1	already published at pub.dev
package:sse	4.1.8	already published at pub.dev
package:stack_trace	1.12.2-wip	(error) pubspec version (1.12.2-wip) and changelog (1.12.2-dev) don't agree
package:stream_channel	2.1.4	already published at pub.dev
package:stream_transform	2.1.2-wip	WIP (no publish necessary)
package:string_scanner	1.4.1	already published at pub.dev
package:term_glyph	1.2.3-wip	WIP (no publish necessary)
package:test_reflective_loader	0.5.0	ready to publish	test_reflective_loader-v0.5.0
package:timing	1.0.2	already published at pub.dev
package:unified_analytics	8.0.9	ready to publish	unified_analytics-v8.0.9
package:watcher	1.1.5-wip	WIP (no publish necessary)
package:yaml	3.1.3	already published at pub.dev
package:yaml_edit	2.2.3	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[gemini-code-assist]

Code Review

This is an excellent pull request that unifies the directory watcher implementations for macOS and Windows. By removing the old Windows-specific code and adapting the macOS watcher to be cross-platform, you've significantly improved the maintainability of the codebase. The changes thoughtfully address Windows-specific filesystem quirks, and the refactoring of utility files into event_batching.dart, paths.dart, and testing.dart greatly improves code organization. The test suite has also been enhanced with better utilities and new tests for edge cases like relative paths and case-insensitive filesystems. I have a few minor suggestions to further polish this work, mainly around documentation and test cleanup. Overall, this is a high-quality and impactful change.

[github-actions]

PR Health

License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
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pkgs/bazel_worker/benchmark/benchmark.dart
pkgs/benchmark_harness/integration_test/perf_benchmark_test.dart
pkgs/boolean_selector/example/example.dart
pkgs/clock/lib/clock.dart
pkgs/clock/lib/src/clock.dart
pkgs/clock/lib/src/default.dart
pkgs/clock/lib/src/stopwatch.dart
pkgs/clock/lib/src/utils.dart
pkgs/clock/test/clock_test.dart
pkgs/clock/test/default_test.dart
pkgs/clock/test/stopwatch_test.dart
pkgs/clock/test/utils.dart
pkgs/coverage/lib/src/coverage_options.dart
pkgs/html/example/main.dart
pkgs/html/lib/dom.dart
pkgs/html/lib/dom_parsing.dart
pkgs/html/lib/html_escape.dart
pkgs/html/lib/parser.dart
pkgs/html/lib/src/constants.dart
pkgs/html/lib/src/encoding_parser.dart
pkgs/html/lib/src/html_input_stream.dart
pkgs/html/lib/src/list_proxy.dart
pkgs/html/lib/src/query_selector.dart
pkgs/html/lib/src/token.dart
pkgs/html/lib/src/tokenizer.dart
pkgs/html/lib/src/treebuilder.dart
pkgs/html/lib/src/utils.dart
pkgs/html/test/dom_test.dart
pkgs/html/test/parser_feature_test.dart
pkgs/html/test/parser_test.dart
pkgs/html/test/query_selector_test.dart
pkgs/html/test/selectors/level1_baseline_test.dart
pkgs/html/test/selectors/level1_lib.dart
pkgs/html/test/selectors/selectors.dart
pkgs/html/test/support.dart
pkgs/html/test/tokenizer_test.dart
pkgs/html/test/trie_test.dart
pkgs/html/tool/generate_trie.dart
pkgs/pubspec_parse/test/git_uri_test.dart
pkgs/stack_trace/example/example.dart
pkgs/watcher/test/custom_watcher_factory_test.dart
pkgs/yaml_edit/example/example.dart

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Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
watcher	Non-Breaking	1.1.4	1.1.5-wip	1.2.0 Got "1.1.5-wip" expected >= "1.2.0" (non-breaking changes)	⚠️

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Coverage ⚠️

File	Coverage
pkgs/watcher/lib/src/directory_watcher.dart	💚 50 %
pkgs/watcher/lib/src/directory_watcher/directory_list.dart	💚 68 % ⬆️ 1 %
pkgs/watcher/lib/src/directory_watcher/event_tree.dart	💚 69 %
pkgs/watcher/lib/src/directory_watcher/linux/native_watch.dart	💚 100 %
pkgs/watcher/lib/src/directory_watcher/linux/watch_tree.dart	💚 97 %
pkgs/watcher/lib/src/directory_watcher/linux/watch_tree_root.dart	💚 94 %
pkgs/watcher/lib/src/directory_watcher/macos/directory_tree.dart	💔 0 % ⬇️ NaN %
pkgs/watcher/lib/src/directory_watcher/macos/native_watch.dart	💔 0 % ⬇️ NaN %
pkgs/watcher/lib/src/directory_watcher/macos/watched_directory_tree.dart	💔 0 % ⬇️ NaN %
pkgs/watcher/lib/src/directory_watcher/polling.dart	💔 78 % ⬇️ 6 %
pkgs/watcher/lib/src/directory_watcher/windows.dart	💔 0 % ⬇️ NaN %
pkgs/watcher/lib/src/directory_watcher/windows_isolate_directory_watcher.dart	💔 0 % ⬇️ NaN %
pkgs/watcher/lib/src/event.dart	💚 76 % ⬆️ 6 %
pkgs/watcher/lib/src/event_batching.dart	💚 100 %
pkgs/watcher/lib/src/file_watcher/native.dart	💚 81 %
pkgs/watcher/lib/src/paths.dart	💚 71 %
pkgs/watcher/lib/src/testing.dart	💚 25 %

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Changelog Entry ✔️

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[natebosch]

[nit] IMO this name is less readable than if the operations were split up. Consider using an extension method if you prefer it to read as checkAndConvert(event).splitMoves().

[davidmorgan]

Thanks--changed to a method on Event, splitIfMove.

[natebosch]

This still has a race condition - I imagine that's at least part of the reason for the long 1 second delay before retries?

Should we instead be running with -j 1? Or should we use a file lock to remove the race condition?

[davidmorgan]

Yeeeeah it's not idea.

I don't see a good way to use file locking, the two tests that should collaborate to avoid the race don't have any files in common.

Using -j 1 is awkward because of the current setup using per-platform entrypoints that call *_tests like this file_tests.

A simpler option is to have exactly one test that changes the current directory, moved this out to relative_directory_test.dart which tests both native+polling watchers, please see what you think.

[chloestefantsova]

LGTM given the comments on this PR are addressed.

[davidmorgan]

Thanks! PTAL.

[davidmorgan]

Thanks--changed to a method on Event, splitIfMove.

[davidmorgan]

Yeeeeah it's not idea.

I don't see a good way to use file locking, the two tests that should collaborate to avoid the race don't have any files in common.

Using -j 1 is awkward because of the current setup using per-platform entrypoints that call *_tests like this file_tests.

A simpler option is to have exactly one test that changes the current directory, moved this out to relative_directory_test.dart which tests both native+polling watchers, please see what you think.