test: deflake test-worker-message-port-transfer-filehandle-fd0

test/parallel/test-worker-message-port-transfer-filehandle-fd0.js

@@ -1,13 +1,14 @@
 'use strict';
 
-// A FileHandle whose transfer is discarded has to close its file descriptor.
-// Descriptor 0 is an ordinary descriptor once stdin has been closed, so the
-// scenario runs in a child process that can afford to lose its stdin.
+// A FileHandle whose transfer is discarded has to close its file descriptor,
+// descriptor 0 included. The child gets this file as stdin, so descriptor 0
+// refers to it from the start and no other thread can take it before the
+// child wraps it in a FileHandle. The child can afford to lose its stdin.
 
 const common = require('../common');
 
 if (common.isWindows)
-  common.skip('descriptor numbering after closing stdin is POSIX-specific');
+  common.skip('libuv does not close descriptors 0 to 2 on Windows');
 
 const assert = require('assert');
 const fs = require('fs');
@@ -16,11 +17,13 @@ if (process.argv[2] === 'child') {
   const vm = require('vm');
   const { MessageChannel, moveMessagePortToContext } =
     require('worker_threads');
+  const { internalBinding } = require('internal/test/binding');
+  const { FileHandle } = require('internal/fs/promises');
+  const { FileHandle: NativeFileHandle } = internalBinding('fs');
 
   (async function() {
-    fs.closeSync(0);
-    const fh = await fs.promises.open(__filename);
-    assert.strictEqual(fh.fd, 0);
+    const { dev, ino } = fs.fstatSync(0, { bigint: true });
+    const fh = new FileHandle(new NativeFileHandle(0));
 
     const { port1, port2 } = new MessageChannel();
     // A port living in another context cannot receive the handle, so the
@@ -34,13 +37,24 @@ if (process.argv[2] === 'child') {
     port1.postMessage(fh, [ fh ]);
     await discarded;
 
-    assert.throws(() => fs.fstatSync(0), { code: 'EBADF' });
+    // Another thread may already have reused descriptor 0, but not for this
+    // file.
+    let stats;
+    try {
+      stats = fs.fstatSync(0, { bigint: true });
+    } catch (err) {
+      assert.strictEqual(err.code, 'EBADF');
+    }
+    if (stats)
+      assert.notDeepStrictEqual([stats.dev, stats.ino], [dev, ino]);
     port1.close();
   })().then(common.mustCall());
   return;
 }
 
-const { spawnSync } = require('child_process');
-const result = spawnSync(process.execPath, [ __filename, 'child' ],
-                         { stdio: [ 'ignore', 'inherit', 'inherit' ] });
-assert.strictEqual(result.status, 0);
+const { spawnSyncAndExitWithoutError } = require('../common/child_process');
+const fd = fs.openSync(__filename);
+spawnSyncAndExitWithoutError(process.execPath,
+                             [ '--expose-internals', __filename, 'child' ],
+                             { stdio: [ fd, 'inherit', 'inherit' ] });
+fs.closeSync(fd);