Fix a flaky test and work around issue 16003 in pkg/watcher.

pkg/watcher/test/utils.dart

Index: pkg/watcher/test/utils.dart
diff --git a/pkg/watcher/test/utils.dart b/pkg/watcher/test/utils.dart
index f7e35f18af7da0d1e074112180e876b5c28e7a52..885018bd1db3809c2d9b508df63fa9a9080bf934 100644
--- a/pkg/watcher/test/utils.dart
+++ b/pkg/watcher/test/utils.dart
@@ -116,7 +116,7 @@ ScheduledStream<WatchEvent> _watcherEvents;
 void startWatcher({String dir}) {
   var testCase = currentTestCase.description;
   if (MacOSDirectoryWatcher.logDebugInfo) {
-    print("starting watcher for $testCase");
+    print("starting watcher for $testCase (${new DateTime.now()})");
   }
 
   // We want to wait until we're ready *after* we subscribe to the watcher's
@@ -129,7 +129,7 @@ void startWatcher({String dir}) {
   _watcherEvents = new ScheduledStream(futureStream(schedule(() {
     currentSchedule.onComplete.schedule(() {
       if (MacOSDirectoryWatcher.logDebugInfo) {
-        print("stopping watcher for $testCase");
+        print("stopping watcher for $testCase (${new DateTime.now()})");
       }
 
       _watcher = null;
@@ -298,6 +298,9 @@ void writeFile(String path, {String contents, bool updateModified}) {
       dir.createSync(recursive: true);
     }
 
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] writing file $path");
+    }
     new File(fullPath).writeAsStringSync(contents);
 
     // Manually update the mock modification time for the file.
@@ -314,6 +317,9 @@ void writeFile(String path, {String contents, bool updateModified}) {
 /// Schedules deleting a file in the sandbox at [path].
 void deleteFile(String path) {
   schedule(() {
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] deleting file $path");
+    }
     new File(p.join(_sandboxDir, path)).deleteSync();
   }, "delete file $path");
 }
@@ -323,6 +329,10 @@ void deleteFile(String path) {
 /// If [contents] is omitted, creates an empty file.
 void renameFile(String from, String to) {
   schedule(() {
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] renaming file $from to $to");
+    }
+
     new File(p.join(_sandboxDir, from)).renameSync(p.join(_sandboxDir, to));
 
     // Make sure we always use the same separator on Windows.
@@ -337,6 +347,9 @@ void renameFile(String from, String to) {
 /// Schedules creating a directory in the sandbox at [path].
 void createDir(String path) {
   schedule(() {
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] creating directory $path");
+    }
     new Directory(p.join(_sandboxDir, path)).createSync();
   }, "create directory $path");
 }
@@ -344,6 +357,9 @@ void createDir(String path) {
 /// Schedules renaming a directory in the sandbox from [from] to [to].
 void renameDir(String from, String to) {
   schedule(() {
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] renaming directory $from to $to");
+    }
     new Directory(p.join(_sandboxDir, from))
         .renameSync(p.join(_sandboxDir, to));
   }, "rename directory $from to $to");
@@ -352,6 +368,9 @@ void renameDir(String from, String to) {
 /// Schedules deleting a directory in the sandbox at [path].
 void deleteDir(String path) {
   schedule(() {
+    if (MacOSDirectoryWatcher.logDebugInfo) {
+      print("[test] deleting directory $path");
+    }
     new Directory(p.join(_sandboxDir, path)).deleteSync(recursive: true);
   }, "delete directory $path");
 }