fs: use default w flag for writeFileSync with utf8 encoding

PR-URL: #50990 Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Yagiz Nizipli <[email protected]>

Author: MuriloKakazu

lib/fs.js

@@ -2343,6 +2343,8 @@ function writeFileSync(path, data, options){
 
 validateBoolean(flush,'options.flush');
 
+constflag=options.flag||'w';
+
 // C++ fast path for string data and UTF8 encoding
 if(typeofdata==='string'&&(options.encoding==='utf8'||options.encoding==='utf-8')){
 if(!isInt32(path)){
@@ -2351,7 +2353,7 @@ function writeFileSync(path, data, options){
 
 returnbinding.writeFileUtf8(
 path,data,
-stringToFlags(options.flag),
+stringToFlags(flag),
 parseFileMode(options.mode,'mode',0o666),
 );
 }
@@ -2361,8 +2363,6 @@ function writeFileSync(path, data, options){
 data=Buffer.from(data,options.encoding||'utf8');
 }
 
-constflag=options.flag||'w';
-
 constisUserFd=isFd(path);// File descriptor ownership
 constfd=isUserFd ? path : fs.openSync(path,flag,options.mode);
 

test/parallel/test-fs-write-file-sync.js

@@ -101,6 +101,22 @@ tmpdir.refresh();
 assert.strictEqual(content,'hello world!');
 }
 
+// Test writeFileSync with no flags
+{
+constutf8Data='hello world!';
+for(consttestof[
+{data: utf8Data},
+{data: utf8Data,options: {encoding: 'utf8'}},
+{data: Buffer.from(utf8Data,'utf8').toString('hex'),options: {encoding: 'hex'}},
+]){
+constfile=tmpdir.resolve(`testWriteFileSyncNewFile_${Math.random()}.txt`);
+fs.writeFileSync(file,test.data,test.options);
+
+constcontent=fs.readFileSync(file,{encoding: 'utf-8'});
+assert.strictEqual(content,utf8Data);
+}
+}
+
 // Test writeFileSync with an invalid input
 {
 constfile=tmpdir.resolve('testWriteFileSyncInvalid.txt');