test: deflake async-hooks statwatcher test

test/async-hooks/test-statwatcher.js

@@ -59,10 +59,32 @@ checkInvocations(statwatcher1, { init: 1 },
                  'watcher1: when started to watch second file');
 checkWatcherStart('watcher2', statwatcher2);
 
-setTimeout(() => fs.writeFileSync(file1, 'foo++'),
-           common.platformTimeout(100));
+let w2Initialized = false;
+let writeFile2AfterW1 = false;
+
+const onW2Initialized = (curr, prev) => {
+  if (curr.nlink !== 0 || prev.nlink !== 0)
+    return;
+
+  w2.removeListener('change', onW2Initialized);
+  w2Initialized = true;
+  if (writeFile2AfterW1) {
+    setTimeout(() => fs.writeFileSync(file2, 'bar++'),
+               common.platformTimeout(100));
+  }
+};
+w2.on('change', onW2Initialized);
+
 w1.on('change', common.mustCallAtLeast((curr, prev) => {
   console.log('w1 change to', curr, 'from', prev);
+  // Wait for the initial ENOENT poll before creating the file. Otherwise the
+  // first stat can race with the write and use the created file as the baseline.
+  if (curr.nlink === 0 && prev.nlink === 0) {
+    setTimeout(() => fs.writeFileSync(file1, 'foo++'),
+               common.platformTimeout(100));
+    return;
+  }
+
   // Wait until we get the write above.
   if (prev.size !== 0 || curr.size !== 5)
     return;
@@ -74,8 +96,11 @@ w1.on('change', common.mustCallAtLeast((curr, prev) => {
     checkInvocations(statwatcher2, { init: 1 },
                      'watcher2: when unwatched first file');
 
-    setTimeout(() => fs.writeFileSync(file2, 'bar++'),
-               common.platformTimeout(100));
+    writeFile2AfterW1 = true;
+    if (w2Initialized) {
+      setTimeout(() => fs.writeFileSync(file2, 'bar++'),
+                 common.platformTimeout(100));
+    }
     w2.on('change', common.mustCallAtLeast((curr, prev) => {
       console.log('w2 change to', curr, 'from', prev);
       // Wait until we get the write above.