Ignore directory modify events on Mac. (#2296)

pkgs/watcher/CHANGELOG.md

diff --git a/pkgs/watcher/CHANGELOG.md b/pkgs/watcher/CHANGELOG.md
index 0d64856..ad9548d 100644
--- a/pkgs/watcher/CHANGELOG.md
+++ b/pkgs/watcher/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.2.1-wip
+## 1.2.1
 
 - Bug fix: versions before 1.2.0 would allow and ignore a trailing path
   separator passed to `DirectoryWatcher` or `FileWatcher` constructors, restore
@@ -6,6 +6,9 @@
 - In paths passed to `DirectoryWatcher` or `FileWatcher` constructors, remove
   multiple adjacent separators and `.` and `..`, so they will not be returned in
   events.
+- Bug fix: on Mac, stop issuing `assert(false)` when a `modifyDirectory` event
+  is ignored, so the unused events are silently ignored instead of throwing in
+  debug builds.
 
 ## 1.2.0
 

pkgs/watcher/lib/src/event.dart

diff --git a/pkgs/watcher/lib/src/event.dart b/pkgs/watcher/lib/src/event.dart
index 4e0fad8..e2e6e2f 100644
--- a/pkgs/watcher/lib/src/event.dart
+++ b/pkgs/watcher/lib/src/event.dart
@@ -23,19 +23,10 @@
   /// Returns `null` if [event] should be ignored on this platform.
   static Event? checkAndConvert(FileSystemEvent event) {
     var result = Event._(event);
-    if (Platform.isMacOS) {
-      if (result.type.isNeverReceivedOnMacOS) {
-        assert(false);
-        return null;
-      }
-    } else if (Platform.isWindows) {
-      if (result.type.isIgnoredOnWindows) {
-        return null;
-      }
-    } else if (Platform.isLinux) {
-      if (result.type.isIgnoredOnLinux) {
-        return null;
-      }
+    if (result.type.isIgnored) return null;
+    if (Platform.isMacOS && result.type.isNeverReceivedOnMacOS) {
+      assert(false);
+      return null;
     }
     return result;
   }
@@ -126,22 +117,19 @@
 
   bool get isNeverReceivedOnMacOS {
     // See https://github.com/dart-lang/sdk/issues/14806.
-    if (this == moveFile || this == moveDirectory) {
-      return true;
-    }
-    if (this == modifyDirectory) return true;
-    return false;
+    return this == moveFile || this == moveDirectory;
   }
 
-  bool get isIgnoredOnWindows {
-    // Ignore [modifyDirectory] because it's always accompanied by either
-    // [createDirectory] or [deleteDirectory].
-    return this == modifyDirectory;
-  }
-
-  bool get isIgnoredOnLinux {
-    // Ignore [modifyDirectory], it arrives when the directory attributes
-    // changed which is not useful.
+  bool get isIgnored {
+    // On Windows, `modifyDirectory` is always accompanied by either
+    // `createDirectory` or `deleteDirectory`, so it's not needed.
+    //
+    // On Linux, `modifyDirectory` means the directory attributes such as
+    // permissions changed, so it's not a useful event.
+    //
+    // `modifyDirectory` on Mac also relates to directory attributes but is
+    // harder to repro, using `unzip` works. It's not a useful event. See
+    // https://github.com/dart-lang/tools/issues/2283.
     return this == modifyDirectory;
   }
 }

pkgs/watcher/pubspec.yaml

diff --git a/pkgs/watcher/pubspec.yaml b/pkgs/watcher/pubspec.yaml
index 5faf63b..7089293 100644
--- a/pkgs/watcher/pubspec.yaml
+++ b/pkgs/watcher/pubspec.yaml
@@ -1,5 +1,5 @@
 name: watcher
-version: 1.2.1-wip
+version: 1.2.1
 description: >-
   A file system watcher. It monitors changes to contents of directories and
   sends notifications when files have been added, removed, or modified.