Fix PollingFileWatcher.ready for files that don't exist (#157)
There were a few issues here:
- FileWatcher.ready never fired for files that don't exist because of logic inside FileWatcher existing early if the modification time was `null`
- The test I recently added trying to catch this was incorrectly passing because the mock timestamp code was set so that files that had not been created would return a 0-mtime whereas in the real implementation they return `null`
So this change
a) updates the mock to return `null` for uncreated files (to match the real implementation) which breaks a bunch of tests
b) fixes those tests by updating FileWatcher._poll() to handle `null` mtime separately from being the first poll.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7743fc7..7893daf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
## 1.1.1-wip
+- Ensure `PollingFileWatcher.ready` completes for files that do not exist.
+
## 1.1.0
- Require Dart SDK >= 3.0.0
diff --git a/lib/src/file_watcher/polling.dart b/lib/src/file_watcher/polling.dart
index 6f1eee4..15ff9ab 100644
--- a/lib/src/file_watcher/polling.dart
+++ b/lib/src/file_watcher/polling.dart
@@ -39,8 +39,7 @@
/// The previous modification time of the file.
///
- /// Used to tell when the file was modified. This is `null` before the file's
- /// mtime has first been checked.
+ /// `null` indicates the file does not (or did not on the last poll) exist.
DateTime? _lastModified;
_PollingFileWatcher(this.path, Duration pollingDelay) {
@@ -50,13 +49,14 @@
/// Checks the mtime of the file and whether it's been removed.
Future<void> _poll() async {
- // We don't mark the file as removed if this is the first poll (indicated by
- // [_lastModified] being null). Instead, below we forward the dart:io error
- // that comes from trying to read the mtime below.
+ // We don't mark the file as removed if this is the first poll. Instead,
+ // below we forward the dart:io error that comes from trying to read the
+ // mtime below.
var pathExists = await File(path).exists();
if (_eventsController.isClosed) return;
if (_lastModified != null && !pathExists) {
+ _flagReady();
_eventsController.add(WatchEvent(ChangeType.REMOVE, path));
unawaited(close());
return;
@@ -67,22 +67,34 @@
modified = await modificationTime(path);
} on FileSystemException catch (error, stackTrace) {
if (!_eventsController.isClosed) {
+ _flagReady();
_eventsController.addError(error, stackTrace);
await close();
}
}
- if (_eventsController.isClosed) return;
+ if (_eventsController.isClosed) {
+ _flagReady();
+ return;
+ }
- if (_lastModified == modified) return;
-
- if (_lastModified == null) {
+ if (!isReady) {
// If this is the first poll, don't emit an event, just set the last mtime
// and complete the completer.
_lastModified = modified;
+ _flagReady();
+ return;
+ }
+
+ if (_lastModified == modified) return;
+
+ _lastModified = modified;
+ _eventsController.add(WatchEvent(ChangeType.MODIFY, path));
+ }
+
+ /// Flags this watcher as ready if it has not already been done.
+ void _flagReady() {
+ if (!isReady) {
_readyCompleter.complete();
- } else {
- _lastModified = modified;
- _eventsController.add(WatchEvent(ChangeType.MODIFY, path));
}
}
diff --git a/lib/src/stat.dart b/lib/src/stat.dart
index 06e3feb..fe0f155 100644
--- a/lib/src/stat.dart
+++ b/lib/src/stat.dart
@@ -6,7 +6,7 @@
/// A function that takes a file path and returns the last modified time for
/// the file at that path.
-typedef MockTimeCallback = DateTime Function(String path);
+typedef MockTimeCallback = DateTime? Function(String path);
MockTimeCallback? _mockTimeCallback;
diff --git a/test/utils.dart b/test/utils.dart
index 214d669..7867b9f 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -67,7 +67,7 @@
'Path is not in the sandbox: $path not in ${d.sandbox}');
var mtime = _mockFileModificationTimes[normalized];
- return DateTime.fromMillisecondsSinceEpoch(mtime ?? 0);
+ return mtime != null ? DateTime.fromMillisecondsSinceEpoch(mtime) : null;
});
// We want to wait until we're ready *after* we subscribe to the watcher's
@@ -195,6 +195,11 @@
Future allowModifyEvent(String path) =>
_expectOrCollect(mayEmit(isWatchEvent(ChangeType.MODIFY, path)));
+/// Track a fake timestamp to be used when writing files. This always increases
+/// so that files that are deleted and re-created do not have their timestamp
+/// set back to a previously used value.
+int _nextTimestamp = 1;
+
/// Schedules writing a file in the sandbox at [path] with [contents].
///
/// If [contents] is omitted, creates an empty file. If [updateModified] is
@@ -216,14 +221,15 @@
if (updateModified) {
path = p.normalize(path);
- _mockFileModificationTimes.update(path, (value) => value + 1,
- ifAbsent: () => 1);
+ _mockFileModificationTimes[path] = _nextTimestamp++;
}
}
/// Schedules deleting a file in the sandbox at [path].
void deleteFile(String path) {
File(p.join(d.sandbox, path)).deleteSync();
+
+ _mockFileModificationTimes.remove(path);
}
/// Schedules renaming a file in the sandbox from [from] to [to].
@@ -245,6 +251,16 @@
/// Schedules renaming a directory in the sandbox from [from] to [to].
void renameDir(String from, String to) {
Directory(p.join(d.sandbox, from)).renameSync(p.join(d.sandbox, to));
+
+ // Migrate timestamps for any files in this folder.
+ final knownFilePaths = _mockFileModificationTimes.keys.toList();
+ for (final filePath in knownFilePaths) {
+ if (p.isWithin(from, filePath)) {
+ _mockFileModificationTimes[filePath.replaceAll(from, to)] =
+ _mockFileModificationTimes[filePath]!;
+ _mockFileModificationTimes.remove(filePath);
+ }
+ }
}
/// Schedules deleting a directory in the sandbox at [path].
