test: add filehandle sync() and datasync() tests

To increase test coverage for fs.promises, added tests for filehandle.sync and filehandle.datasync. PR-URL: #20530 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

Author: Masashi Hirano

test/parallel/test-fs-promises-file-handle-sync.js

@@ -0,0 +1,27 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+constfixtures=require('../common/fixtures');
+consttmpdir=require('../common/tmpdir');
+
+const{ access, copyFile, open }=require('fs').promises;
+constpath=require('path');
+
+common.crashOnUnhandledRejection();
+
+asyncfunctionvalidateSync(){
+tmpdir.refresh();
+constdest=path.resolve(tmpdir.path,'baz.js');
+awaitcopyFile(fixtures.path('baz.js'),dest);
+awaitaccess(dest,'r');
+consthandle=awaitopen(dest,'r+');
+awaithandle.datasync();
+awaithandle.sync();
+constbuf=Buffer.from('hello world');
+awaithandle.write(buf);
+constret=awaithandle.read(Buffer.alloc(11),0,11,0);
+assert.strictEqual(ret.bytesRead,11);
+assert.deepStrictEqual(ret.buffer,buf);
+}
+
+validateSync();