Code style: always-parens for arrow functions

.eslintrc

@@ -76,6 +76,8 @@ rules:
   # list: http://eslint.org/docs/rules/#ecmascript-6
   ## Suggest using 'const' wherever possible
   prefer-const: 2
+  ## always require paren in arrow functions, even in the single-argument case
+  arrow-parens: [2, "always"]
 
   # Strict Mode
   # list: https://github.com/eslint/eslint/tree/master/docs/rules#strict-mode

test/common.js

@@ -470,7 +470,7 @@ exports.fail = function(msg) {
 // A stream to push an array into a REPL
 function ArrayStream() {
   this.run = function(data) {
-    data.forEach(line => {
+    data.forEach((line) => {
       this.emit('data', line + '\n');
     });
   };

test/parallel/test-assert.js

@@ -482,7 +482,7 @@ testBlockTypeError(assert.throws, undefined);
 testBlockTypeError(assert.doesNotThrow, undefined);
 
 // https://github.com/nodejs/node/issues/3275
-assert.throws(() => { throw 'error'; }, err => err === 'error');
-assert.throws(() => { throw new Error(); }, err => err instanceof Error);
+assert.throws(() => { throw 'error'; }, (err) => err === 'error');
+assert.throws(() => { throw new Error(); }, (err) => err instanceof Error);
 
 console.log('All OK');

test/parallel/test-async-wrap-check-providers.js

@@ -20,7 +20,7 @@ keyList.splice(0, 1);
 
 
 function init(id) {
-  keyList = keyList.filter(e => e != pkeys[id]);
+  keyList = keyList.filter((e) => e != pkeys[id]);
 }
 
 function noop() { }

test/parallel/test-cluster-disconnect-handles.js

@@ -31,7 +31,7 @@ if (cluster.isMaster) {
   // scanner but is ignored by atoi(3).  Heinous hack.
   cluster.setupMaster({ execArgv: [`--debug=${common.PORT}.`] });
   const worker = cluster.fork();
-  worker.on('message', common.mustCall(message => {
+  worker.on('message', common.mustCall((message) => {
     assert.strictEqual(Array.isArray(message), true);
     assert.strictEqual(message[0], 'listening');
     let continueRecv = false;
@@ -40,9 +40,9 @@ if (cluster.isMaster) {
     const debugClient = net.connect({ host, port: common.PORT });
     const protocol = new Protocol();
     debugClient.setEncoding('utf8');
-    debugClient.on('data', data => protocol.execute(data));
+    debugClient.on('data', (data) => protocol.execute(data));
     debugClient.once('connect', common.mustCall(() => {
-      protocol.onResponse = common.mustCall(res => {
+      protocol.onResponse = common.mustCall((res) => {
         protocol.onResponse = (res) => {
           // It can happen that the first continue was sent before the break
           // event was received. If that's the case, send also a continue from
@@ -85,7 +85,7 @@ if (cluster.isMaster) {
     throw ex;
   });
 } else {
-  const server = net.createServer(socket => socket.pipe(socket));
+  const server = net.createServer((socket) => socket.pipe(socket));
   const cb = () => {
     process.send(['listening', server.address()]);
     debugger;

test/parallel/test-debug-no-context.js

@@ -17,7 +17,7 @@ proc.on('exit', common.mustCall((exitCode, signalCode) => {
 }));
 let stdout = '';
 proc.stdout.setEncoding('utf8');
-proc.stdout.on('data', data => stdout += data);
+proc.stdout.on('data', (data) => stdout += data);
 process.on('exit', () => {
   assert(stdout.includes('Promise { 42 }'));
   assert(stdout.includes('Promise { 1337 }'));

test/parallel/test-debug-port-cluster.js

@@ -15,7 +15,7 @@ const child = spawn(process.execPath, args);
 child.stderr.setEncoding('utf8');
 
 let stderr = '';
-child.stderr.on('data', data => {
+child.stderr.on('data', (data) => {
   stderr += data;
   if (child.killed !== true && stderr.includes('all workers are running'))
     child.kill();

test/parallel/test-net-socket-local-address.js

@@ -13,7 +13,7 @@ var conns = 0;
 var clientLocalPorts = [];
 var serverRemotePorts = [];
 const client = new net.Socket();
-const server = net.createServer(socket => {
+const server = net.createServer((socket) => {
   serverRemotePorts.push(socket.remotePort);
   socket.end();
 });

test/parallel/test-process-emit.js

@@ -3,15 +3,15 @@ const common = require('../common');
 const assert = require('assert');
 const sym = Symbol();
 
-process.on('normal', common.mustCall(data => {
+process.on('normal', common.mustCall((data) => {
   assert.strictEqual(data, 'normalData');
 }));
 
-process.on(sym, common.mustCall(data => {
+process.on(sym, common.mustCall((data) => {
   assert.strictEqual(data, 'symbolData');
 }));
 
-process.on('SIGPIPE', common.mustCall(data => {
+process.on('SIGPIPE', common.mustCall((data) => {
   assert.strictEqual(data, 'signalData');
 }));
 

test/parallel/test-repl-require.js

@@ -7,7 +7,7 @@ const net = require('net');
 process.chdir(common.fixturesDir);
 const repl = require('repl');
 
-const server = net.createServer(conn => {
+const server = net.createServer((conn) => {
   repl.start('', conn).on('exit', () => {
     conn.destroy();
     server.close();
@@ -22,7 +22,7 @@ var answer = '';
 server.listen(options, function() {
   const conn = net.connect(options);
   conn.setEncoding('utf8');
-  conn.on('data', data => answer += data);
+  conn.on('data', (data) => answer += data);
   conn.write('require("baz")\n.exit\n');
 });
 

test/parallel/test-tls-client-mindhsize.js

@@ -78,12 +78,12 @@ testDHE1024();
 assert.throws(() => test(512, true, assert.fail),
               /DH parameter is less than 1024 bits/);
 
-[0, -1, -Infinity, NaN].forEach(minDHSize => {
+[0, -1, -Infinity, NaN].forEach((minDHSize) => {
   assert.throws(() => tls.connect({ minDHSize }),
                 /minDHSize is not a positive number/);
 });
 
-[true, false, null, undefined, {}, [], '', '1'].forEach(minDHSize => {
+[true, false, null, undefined, {}, [], '', '1'].forEach((minDHSize) => {
   assert.throws(() => tls.connect({ minDHSize }), /minDHSize is not a number/);
 });
 

test/parallel/test-tls-no-sslv3.js

@@ -40,15 +40,15 @@ server.listen(common.PORT, '127.0.0.1', function() {
   client.stdout.pipe(process.stdout);
   client.stderr.pipe(process.stderr);
   client.stderr.setEncoding('utf8');
-  client.stderr.on('data', data => stderr += data);
+  client.stderr.on('data', (data) => stderr += data);
 
   client.once('exit', common.mustCall(function(exitCode) {
     assert.equal(exitCode, 1);
     server.close();
   }));
 });
 
-server.on('tlsClientError', err => errors.push(err));
+server.on('tlsClientError', (err) => errors.push(err));
 
 process.on('exit', function() {
   if (/unknown option -ssl3/.test(stderr)) {

test/parallel/test-util-inspect.js

@@ -106,7 +106,7 @@ for (const showHidden of [true, false]) {
   Uint16Array,
   Uint32Array,
   Uint8Array,
-  Uint8ClampedArray ].forEach(constructor => {
+  Uint8ClampedArray ].forEach((constructor) => {
     const length = 2;
     const byteLength = length * constructor.BYTES_PER_ELEMENT;
     const array = new constructor(new ArrayBuffer(byteLength), 0, length);
@@ -133,7 +133,7 @@ for (const showHidden of [true, false]) {
   Uint16Array,
   Uint32Array,
   Uint8Array,
-  Uint8ClampedArray ].forEach(constructor => {
+  Uint8ClampedArray ].forEach((constructor) => {
     const length = 2;
     const byteLength = length * constructor.BYTES_PER_ELEMENT;
     const array = vm.runInNewContext('new constructor(new ArrayBuffer(' +

test/parallel/test-v8-stats.js

@@ -25,9 +25,9 @@ const expectedHeapSpaces = [
   'large_object_space'
 ];
 const heapSpaceStatistics = v8.getHeapSpaceStatistics();
-const actualHeapSpaceNames = heapSpaceStatistics.map(s => s.space_name);
+const actualHeapSpaceNames = heapSpaceStatistics.map((s) => s.space_name);
 assert.deepEqual(actualHeapSpaceNames.sort(), expectedHeapSpaces.sort());
-heapSpaceStatistics.forEach(heapSpace => {
+heapSpaceStatistics.forEach((heapSpace) => {
   assert.strictEqual(typeof heapSpace.space_name, 'string');
   assert.strictEqual(typeof heapSpace.space_size, 'number');
   assert.strictEqual(typeof heapSpace.space_used_size, 'number');