Fixed #1110 -- Do not report symlink create/delete as a move in DirectorySnapshotDiff#1176
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…ove in DirectorySnapshotDiff A new symlink shares its target's inode because the default stat function follows symlinks. The move-detection heuristic matched that shared inode and reported the creation of a symlink (or the removal of one whose target remains) as a move of the target file, so PollingObserver emitted a spurious FileMovedEvent instead of the create/delete event the native observers emit. Only treat an inode match as a move when the counterpart path is genuinely new (destination) or gone (source), leaving the move-replace behaviour intact. Added regression tests for both the create and delete symlink cases.
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Summary
Fixes #1110.
PollingObserverreported the creation of a new symlink as aFileMovedEventinstead of aFileCreatedEvent, diverging from the native (fsevents/inotify/winapi) observers.Root cause
DirectorySnapshotbuilds its inode index with the defaultstat=os.stat, which follows symlinks. A new symlink therefore reports the same(st_ino, st_dev)as its target.DirectorySnapshotDiff's move detection matches paths by inode, so whendata.trigger -> datais created, the created symlink's inode maps back to the still-presentdata, and the change is emitted as a movedata -> data.trigger(with an emptyfiles_created). The symmetric case — removing a symlink whose target remains — was reported as a move onto the target.Fix
Treat an inode match as a move only when the counterpart path is genuinely new (for the destination) or genuinely gone (for the source):
This leaves real moves — including the move-replace case where the destination pre-existed with a different inode (
test_move_replace) — unchanged, while symlinks/hard links that merely share a target's inode degrade to create/delete events, matching the native observers and the module's own "represent movement as created/deleted when inode logic breaks" note.Verification
test_create_symlink_to_existing_fileandtest_delete_symlink_to_existing_file(skipped on Windows, where symlinks need privileges). Both fail onmasterand pass with this change.tests/test_snapshot_diff.py: 15 passed (including the pre-existingtest_move_replace/test_move_internal).tests/test_observers_polling.pyandtests/test_observers_api.py: 9 passed.ruff checkandruff format --checkclean on the changed files.Disclosure: this change was prepared with AI assistance; I have reviewed and verified it locally against the test suite.