test: add common.noop, default for common.mustCall()

Export a new common.noop no-operation function for general use.
Allow using common.mustCall() without a fn argument to simplify
test cases.

Replace various non-op functions throughout tests with common.noop

PR-URL: https://github.com/nodejs/node/pull/12027
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

test/addons/async-hello-world/test.js

@@ -6,5 +6,5 @@ const binding = require(`./build/${common.buildType}/binding`);
 binding(5, common.mustCall(function(err, val) {
   assert.strictEqual(err, null);
   assert.strictEqual(val, 10);
-  process.nextTick(common.mustCall(function() {}));
+  process.nextTick(common.mustCall());
 }));

test/common/index.js

@@ -12,6 +12,9 @@ const Timer = process.binding('timer_wrap').Timer;
 const testRoot = process.env.NODE_TEST_DIR ?
   fs.realpathSync(process.env.NODE_TEST_DIR) : path.resolve(__dirname, '..');
 
+const noop = () => {};
+
+exports.noop = noop;
 exports.fixturesDir = path.join(__dirname, '..', 'fixtures');
 exports.tmpDirName = 'tmp';
 // PORT should match the definition in test/testpy/__init__.py.
@@ -419,6 +422,13 @@ function runCallChecks(exitCode) {
 
 
 exports.mustCall = function(fn, expected) {
+  if (typeof fn === 'number') {
+    expected = fn;
+    fn = noop;
+  } else if (fn === undefined) {
+    fn = noop;
+  }
+
   if (expected === undefined)
     expected = 1;
   else if (typeof expected !== 'number')
@@ -487,9 +497,9 @@ util.inherits(ArrayStream, stream.Stream);
 exports.ArrayStream = ArrayStream;
 ArrayStream.prototype.readable = true;
 ArrayStream.prototype.writable = true;
-ArrayStream.prototype.pause = function() {};
+ArrayStream.prototype.pause = noop;
-ArrayStream.prototype.resume = function() {};
+ArrayStream.prototype.resume = noop;
-ArrayStream.prototype.write = function() {};
+ArrayStream.prototype.write = noop;
 
 // Returns true if the exit code "exitCode" and/or signal name "signal"
 // represent the exit code and/or signal name of a node process that aborted,

test/debugger/test-debugger-client.js

@@ -129,7 +129,7 @@ addTest(function(client, done) {
 
 let connectCount = 0;
 const script = 'setTimeout(function() { console.log("blah"); });' +
-               'setInterval(function() {}, 1000000);';
+               'setInterval(common.noop, 1000000);';
 
 let nodeProcess;
 
@@ -172,7 +172,7 @@ function doTest(cb, done) {
         console.error('>>> connecting...');
         c.connect(debug.port);
         c.on('break', function() {
-          c.reqContinue(function() {});
+          c.reqContinue(common.noop);
         });
         c.on('ready', function() {
           connectCount++;

test/parallel/test-assert.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const a = require('assert');
 
@@ -515,6 +515,7 @@ testAssertionMessage(/a/, '/a/');
 testAssertionMessage(/abc/gim, '/abc/gim');
 testAssertionMessage(function f() {}, '[Function: f]');
 testAssertionMessage(function() {}, '[Function]');
+testAssertionMessage(common.noop, '[Function: noop]');
 testAssertionMessage({}, '{}');
 testAssertionMessage(circular, '{ y: 1, x: [Circular] }');
 testAssertionMessage({a: undefined, b: null}, '{ a: undefined, b: null }');

test/parallel/test-child-process-disconnect.js

@@ -57,7 +57,7 @@ if (process.argv[2] === 'child') {
   }));
 
   // the process should also self terminate without using signals
-  child.on('exit', common.mustCall(function() {}));
+  child.on('exit', common.mustCall());
 
   // when child is listening
   child.on('message', function(obj) {

test/parallel/test-child-process-kill.js

@@ -4,9 +4,9 @@ const assert = require('assert');
 const spawn = require('child_process').spawn;
 const cat = spawn(common.isWindows ? 'cmd' : 'cat');
 
-cat.stdout.on('end', common.mustCall(function() {}));
+cat.stdout.on('end', common.mustCall());
 cat.stderr.on('data', common.mustNotCall());
-cat.stderr.on('end', common.mustCall(function() {}));
+cat.stderr.on('end', common.mustCall());
 
 cat.on('exit', common.mustCall(function(code, signal) {
   assert.strictEqual(code, null);

test/parallel/test-child-process-stdin.js

@@ -22,11 +22,11 @@ cat.stdout.on('data', function(chunk) {
   response += chunk;
 });
 
-cat.stdout.on('end', common.mustCall(function() {}));
+cat.stdout.on('end', common.mustCall());
 
 cat.stderr.on('data', common.mustNotCall());
 
-cat.stderr.on('end', common.mustCall(function() {}));
+cat.stderr.on('end', common.mustCall());
 
 cat.on('exit', common.mustCall(function(status) {
   assert.strictEqual(0, status);

test/parallel/test-cluster-eaccess.js

@@ -14,10 +14,10 @@ if (cluster.isMaster) {
   const worker = cluster.fork();
 
   // makes sure master is able to fork the worker
-  cluster.on('fork', common.mustCall(function() {}));
+  cluster.on('fork', common.mustCall());
 
   // makes sure the worker is ready
-  worker.on('online', common.mustCall(function() {}));
+  worker.on('online', common.mustCall());
 
   worker.on('message', common.mustCall(function(err) {
     // disconnect first, so that we will not leave zombies

test/parallel/test-cluster-setup-master-emit.js

@@ -22,5 +22,5 @@ function emitAndCatch2(next) {
 }
 
 emitAndCatch(common.mustCall(function() {
-  emitAndCatch2(common.mustCall(function() {}));
+  emitAndCatch2(common.mustCall());
 }));

test/parallel/test-cluster-worker-destroy.js

@@ -17,8 +17,8 @@ if (cluster.isMaster) {
   worker2 = cluster.fork();
 
   [worker1, worker2].forEach(function(worker) {
-    worker.on('disconnect', common.mustCall(function() {}));
+    worker.on('disconnect', common.mustCall());
-    worker.on('exit', common.mustCall(function() {}));
+    worker.on('exit', common.mustCall());
   });
 } else {
   if (cluster.worker.id === 1) {

test/parallel/test-cluster-worker-wait-server-close.js

@@ -20,7 +20,7 @@ if (cluster.isWorker) {
 
   // Although not typical, the worker process can exit before the disconnect
   // event fires. Use this to keep the process open until the event has fired.
-  const keepOpen = setInterval(function() {}, 9999);
+  const keepOpen = setInterval(common.noop, 9999);
 
   // Check worker events and properties
   process.once('disconnect', function() {

test/parallel/test-common.js

@@ -7,9 +7,9 @@ global.gc = 42;  // Not a valid global unless --expose_gc is set.
 assert.deepStrictEqual(common.leakedGlobals(), ['gc']);
 
 assert.throws(function() {
-  common.mustCall(function() {}, 'foo');
+  common.mustCall(common.noop, 'foo');
 }, /^TypeError: Invalid expected value: foo$/);
 
 assert.throws(function() {
-  common.mustCall(function() {}, /foo/);
+  common.mustCall(common.noop, /foo/);
 }, /^TypeError: Invalid expected value: \/foo\/$/);

test/parallel/test-crypto-random.js

@@ -17,7 +17,7 @@ const expectedErrorRegexp = /^TypeError: size must be a number >= 0$/;
 [crypto.randomBytes, crypto.pseudoRandomBytes].forEach(function(f) {
   [-1, undefined, null, false, true, {}, []].forEach(function(value) {
     assert.throws(function() { f(value); }, expectedErrorRegexp);
-    assert.throws(function() { f(value, function() {}); }, expectedErrorRegexp);
+    assert.throws(function() { f(value, common.noop); }, expectedErrorRegexp);
   });
 
   [0, 1, 2, 4, 16, 256, 1024].forEach(function(len) {

test/parallel/test-dgram-close-is-not-callback.js

@@ -17,5 +17,5 @@ const portGetter = dgram.createSocket('udp4')
     socket.close('bad argument');
     portGetter.close();
 
-    socket.on('close', common.mustCall(function() {}));
+    socket.on('close', common.mustCall());
   }));

test/parallel/test-dgram-close.js

@@ -18,8 +18,8 @@ const portGetter = dgram.createSocket('udp4')
                 portGetter.address().port,
                 portGetter.address().address);
 
-    assert.strictEqual(socket.close(common.mustCall(function() {})), socket);
+    assert.strictEqual(socket.close(common.mustCall()), socket);
-    socket.on('close', common.mustCall(function() {}));
+    socket.on('close', common.mustCall());
     socket = null;
 
     // Verify that accessing handle after closure doesn't throw

test/parallel/test-dgram-send-empty-buffer.js

@@ -22,6 +22,6 @@ client.bind(0, common.mustCall(function() {
 
   const buf = Buffer.alloc(0);
   let interval = setInterval(function() {
-    client.send(buf, 0, 0, port, '127.0.0.1', common.mustCall(function() {}));
+    client.send(buf, 0, 0, port, '127.0.0.1', common.mustCall());
   }, 10);
 }));

test/parallel/test-domain-crypto.js

@@ -17,7 +17,7 @@ global.domain = require('domain');
 
 // should not throw a 'TypeError: undefined is not a function' exception
 crypto.randomBytes(8);
-crypto.randomBytes(8, function() {});
+crypto.randomBytes(8, common.noop);
 crypto.pseudoRandomBytes(8);
-crypto.pseudoRandomBytes(8, function() {});
+crypto.pseudoRandomBytes(8, common.noop);
-crypto.pbkdf2('password', 'salt', 8, 8, function() {});
+crypto.pbkdf2('password', 'salt', 8, 8, common.noop);

test/parallel/test-domain-exit-dispose.js

@@ -22,7 +22,7 @@ function err() {
   function err2() {
     // this timeout should never be called, since the domain gets
     // disposed when the error happens.
-    setTimeout(common.mustCall(() => {}, 0), 1);
+    setTimeout(common.mustNotCall(), 1);
 
     // this function doesn't exist, and throws an error as a result.
     err3(); // eslint-disable-line no-undef

test/parallel/test-domain-timers.js

@@ -32,4 +32,4 @@ immediated.run(function() {
   });
 });
 
-timeout = setTimeout(function() {}, 10 * 1000);
+timeout = setTimeout(common.noop, 10 * 1000);

test/parallel/test-domain.js

@@ -1,7 +1,7 @@
 'use strict';
 // Simple tests of most basic domain functionality.
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const domain = require('domain');
 const events = require('events');
@@ -238,7 +238,7 @@ let fst = fs.createReadStream('stream for nonexistent file');
 d.add(fst);
 expectCaught++;
 
-[42, null, , false, function() {}, 'string'].forEach(function(something) {
+[42, null, , false, common.noop, 'string'].forEach(function(something) {
   const d = new domain.Domain();
   d.run(function() {
     process.nextTick(function() {

test/parallel/test-env-var-no-warnings.js

@@ -29,7 +29,7 @@ if (process.argv[2] === 'child') {
   test({ NODE_NO_WARNINGS: false });
   test({ NODE_NO_WARNINGS: {} });
   test({ NODE_NO_WARNINGS: [] });
-  test({ NODE_NO_WARNINGS: function() {} });
+  test({ NODE_NO_WARNINGS: common.noop });
   test({ NODE_NO_WARNINGS: 0 });
   test({ NODE_NO_WARNINGS: -1 });
   test({ NODE_NO_WARNINGS: '0' });

test/parallel/test-event-emitter-check-listener-leaks.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const events = require('events');
 
@@ -7,40 +7,40 @@ let e = new events.EventEmitter();
 
 // default
 for (let i = 0; i < 10; i++) {
-  e.on('default', function() {});
+  e.on('default', common.noop);
 }
 assert.ok(!e._events['default'].hasOwnProperty('warned'));
-e.on('default', function() {});
+e.on('default', common.noop);
 assert.ok(e._events['default'].warned);
 
 // symbol
 const symbol = Symbol('symbol');
 e.setMaxListeners(1);
-e.on(symbol, function() {});
+e.on(symbol, common.noop);
 assert.ok(!e._events[symbol].hasOwnProperty('warned'));
-e.on(symbol, function() {});
+e.on(symbol, common.noop);
 assert.ok(e._events[symbol].hasOwnProperty('warned'));
 
 // specific
 e.setMaxListeners(5);
 for (let i = 0; i < 5; i++) {
-  e.on('specific', function() {});
+  e.on('specific', common.noop);
 }
 assert.ok(!e._events['specific'].hasOwnProperty('warned'));
-e.on('specific', function() {});
+e.on('specific', common.noop);
 assert.ok(e._events['specific'].warned);
 
 // only one
 e.setMaxListeners(1);
-e.on('only one', function() {});
+e.on('only one', common.noop);
 assert.ok(!e._events['only one'].hasOwnProperty('warned'));
-e.on('only one', function() {});
+e.on('only one', common.noop);
 assert.ok(e._events['only one'].hasOwnProperty('warned'));
 
 // unlimited
 e.setMaxListeners(0);
 for (let i = 0; i < 1000; i++) {
-  e.on('unlimited', function() {});
+  e.on('unlimited', common.noop);
 }
 assert.ok(!e._events['unlimited'].hasOwnProperty('warned'));
 
@@ -49,26 +49,26 @@ events.EventEmitter.defaultMaxListeners = 42;
 e = new events.EventEmitter();
 
 for (let i = 0; i < 42; ++i) {
-  e.on('fortytwo', function() {});
+  e.on('fortytwo', common.noop);
 }
 assert.ok(!e._events['fortytwo'].hasOwnProperty('warned'));
-e.on('fortytwo', function() {});
+e.on('fortytwo', common.noop);
 assert.ok(e._events['fortytwo'].hasOwnProperty('warned'));
 delete e._events['fortytwo'].warned;
 
 events.EventEmitter.defaultMaxListeners = 44;
-e.on('fortytwo', function() {});
+e.on('fortytwo', common.noop);
 assert.ok(!e._events['fortytwo'].hasOwnProperty('warned'));
-e.on('fortytwo', function() {});
+e.on('fortytwo', common.noop);
 assert.ok(e._events['fortytwo'].hasOwnProperty('warned'));
 
 // but _maxListeners still has precedence over defaultMaxListeners
 events.EventEmitter.defaultMaxListeners = 42;
 e = new events.EventEmitter();
 e.setMaxListeners(1);
-e.on('uno', function() {});
+e.on('uno', common.noop);
 assert.ok(!e._events['uno'].hasOwnProperty('warned'));
-e.on('uno', function() {});
+e.on('uno', common.noop);
 assert.ok(e._events['uno'].hasOwnProperty('warned'));
 
 // chainable

test/parallel/test-event-emitter-get-max-listeners.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const EventEmitter = require('events');
 
@@ -15,5 +15,5 @@ assert.strictEqual(emitter.getMaxListeners(), 3);
 
 // https://github.com/nodejs/node/issues/523 - second call should not throw.
 const recv = {};
-EventEmitter.prototype.on.call(recv, 'event', function() {});
+EventEmitter.prototype.on.call(recv, 'event', common.noop);
-EventEmitter.prototype.on.call(recv, 'event', function() {});
+EventEmitter.prototype.on.call(recv, 'event', common.noop);

test/parallel/test-event-emitter-listener-count.js

@@ -1,15 +1,15 @@
 'use strict';
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const EventEmitter = require('events');
 
 const emitter = new EventEmitter();
-emitter.on('foo', function() {});
+emitter.on('foo', common.noop);
-emitter.on('foo', function() {});
+emitter.on('foo', common.noop);
-emitter.on('baz', function() {});
+emitter.on('baz', common.noop);
 // Allow any type
-emitter.on(123, function() {});
+emitter.on(123, common.noop);
 
 assert.strictEqual(EventEmitter.listenerCount(emitter, 'foo'), 2);
 assert.strictEqual(emitter.listenerCount('foo'), 2);

test/parallel/test-event-emitter-max-listeners-warning-for-null.js

@@ -18,5 +18,5 @@ process.on('warning', common.mustCall((warning) => {
   assert.ok(warning.message.includes('2 null listeners added.'));
 }));
 
-e.on(null, function() {});
+e.on(null, common.noop);
-e.on(null, function() {});
+e.on(null, common.noop);

test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js

@@ -20,5 +20,5 @@ process.on('warning', common.mustCall((warning) => {
   assert.ok(warning.message.includes('2 Symbol(symbol) listeners added.'));
 }));
 
-e.on(symbol, function() {});
+e.on(symbol, common.noop);
-e.on(symbol, function() {});
+e.on(symbol, common.noop);

test/parallel/test-event-emitter-max-listeners-warning.js

@@ -18,6 +18,6 @@ process.on('warning', common.mustCall((warning) => {
   assert.ok(warning.message.includes('2 event-type listeners added.'));
 }));
 
-e.on('event-type', function() {});
+e.on('event-type', common.noop);
-e.on('event-type', function() {});  // Trigger warning.
+e.on('event-type', common.noop);  // Trigger warning.
-e.on('event-type', function() {});  // Verify that warning is emitted only once.
+e.on('event-type', common.noop);  // Verify that warning is emitted only once.

test/parallel/test-event-emitter-max-listeners.js

@@ -4,7 +4,7 @@ const assert = require('assert');
 const events = require('events');
 const e = new events.EventEmitter();
 
-e.on('maxListeners', common.mustCall(function() {}));
+e.on('maxListeners', common.mustCall());
 
 // Should not corrupt the 'maxListeners' queue.
 e.setMaxListeners(42);

test/parallel/test-event-emitter-once.js

@@ -24,7 +24,7 @@ e.once('e', common.mustCall(function() {
   e.emit('e');
 }));
 
-e.once('e', common.mustCall(function() {}));
+e.once('e', common.mustCall());
 
 e.emit('e');
 

test/parallel/test-event-emitter-remove-all-listeners.js

@@ -70,9 +70,9 @@ function listener() {}
   ee.on('removeListener', function(name, listener) {
     assert.strictEqual(expectLength--, this.listeners('baz').length);
   });
-  ee.on('baz', function() {});
+  ee.on('baz', common.noop);
-  ee.on('baz', function() {});
+  ee.on('baz', common.noop);
-  ee.on('baz', function() {});
+  ee.on('baz', common.noop);
   assert.strictEqual(ee.listeners('baz').length, expectLength + 1);
   ee.removeAllListeners('baz');
   assert.strictEqual(ee.listeners('baz').length, 0);

test/parallel/test-event-emitter-subclass.js

@@ -13,7 +13,7 @@ function MyEE(cb) {
   EventEmitter.call(this);
 }
 
-const myee = new MyEE(common.mustCall(function() {}));
+const myee = new MyEE(common.mustCall());
 
 
 util.inherits(ErrorEE, EventEmitter);
@@ -41,6 +41,6 @@ MyEE2.prototype = new EventEmitter();
 const ee1 = new MyEE2();
 const ee2 = new MyEE2();
 
-ee1.on('x', function() {});
+ee1.on('x', common.noop);
 
 assert.strictEqual(ee2.listenerCount('x'), 0);

test/parallel/test-event-emitter-symbols.js

@@ -6,7 +6,7 @@ const assert = require('assert');
 
 const ee = new EventEmitter();
 const foo = Symbol('foo');
-const listener = common.mustCall(function() {});
+const listener = common.mustCall();
 
 ee.on(foo, listener);
 assert.deepStrictEqual(ee.listeners(foo), [listener]);

test/parallel/test-fs-mkdir.js

@@ -56,4 +56,4 @@ common.refreshTmpDir();
 
 // Keep the event loop alive so the async mkdir() requests
 // have a chance to run (since they don't ref the event loop).
-process.nextTick(function() {});
+process.nextTick(common.noop);

test/parallel/test-fs-read-stream-inherit.js

@@ -39,7 +39,7 @@ let paused = false;
   });
 
 
-  file.on('end', common.mustCall(function() {}));
+  file.on('end', common.mustCall());
 
 
   file.on('close', common.mustCall(function() {
@@ -139,7 +139,7 @@ let paused = false;
   let file7 =
     fs.createReadStream(rangeFile, Object.create({autoClose: false }));
   assert.strictEqual(file7.autoClose, false);
-  file7.on('data', function() {});
+  file7.on('data', common.noop);
   file7.on('end', common.mustCall(function() {
     process.nextTick(common.mustCall(function() {
       assert(!file7.closed);
@@ -169,8 +169,8 @@ let paused = false;
 {
   const options = Object.create({fd: 13337, autoClose: false});
   const file8 = fs.createReadStream(null, options);
-  file8.on('data', function() {});
+  file8.on('data', common.noop);
-  file8.on('error', common.mustCall(function() {}));
+  file8.on('error', common.mustCall());
   process.on('exit', function() {
     assert(!file8.closed);
     assert(!file8.destroyed);
@@ -181,8 +181,8 @@ let paused = false;
 // Make sure stream is destroyed when file does not exist.
 {
   const file9 = fs.createReadStream('/path/to/file/that/does/not/exist');
-  file9.on('data', function() {});
+  file9.on('data', common.noop);
-  file9.on('error', common.mustCall(function() {}));
+  file9.on('error', common.mustCall());
 
   process.on('exit', function() {
     assert(!file9.closed);

test/parallel/test-fs-read-stream.js

@@ -138,7 +138,7 @@ pauseRes.pause();
 pauseRes.resume();
 
 let file7 = fs.createReadStream(rangeFile, {autoClose: false });
-file7.on('data', function() {});
+file7.on('data', common.noop);
 file7.on('end', function() {
   process.nextTick(function() {
     assert(!file7.closed);
@@ -161,13 +161,13 @@ function file7Next() {
 
 // Just to make sure autoClose won't close the stream because of error.
 const file8 = fs.createReadStream(null, {fd: 13337, autoClose: false });
-file8.on('data', function() {});
+file8.on('data', common.noop);
-file8.on('error', common.mustCall(function() {}));
+file8.on('error', common.mustCall());
 
 // Make sure stream is destroyed when file does not exist.
 const file9 = fs.createReadStream('/path/to/file/that/does/not/exist');
-file9.on('data', function() {});
+file9.on('data', common.noop);
-file9.on('error', common.mustCall(function() {}));
+file9.on('error', common.mustCall());
 
 process.on('exit', function() {
   assert(file7.closed);

test/parallel/test-fs-watchfile.js

@@ -15,7 +15,7 @@ assert.throws(function() {
 }, /"watchFile\(\)" requires a listener function/);
 
 assert.throws(function() {
-  fs.watchFile(new Object(), function() {});
+  fs.watchFile(new Object(), common.noop);
 }, /Path must be a string/);
 
 const enoentFile = path.join(common.tmpDir, 'non-existent-file');

test/parallel/test-handle-wrap-close-abort.js

@@ -1,7 +1,7 @@
 'use strict';
 const common = require('../common');
 
-process.on('uncaughtException', common.mustCall(function() {}, 2));
+process.on('uncaughtException', common.mustCall(common.noop, 2));
 
 setTimeout(function() {
   process.nextTick(function() {

test/parallel/test-http-abort-client.js

@@ -38,6 +38,6 @@ server.listen(0, common.mustCall(function() {
     });
 
     // it would be nice if this worked:
-    res.on('close', common.mustCall(function() {}));
+    res.on('close', common.mustCall());
   }));
 }));

test/parallel/test-http-client-aborted-event.js

@@ -13,6 +13,6 @@ server.listen(0, common.mustCall(function() {
     headers: { connection: 'keep-alive' }
   }, common.mustCall(function(res) {
     server.close();
-    res.on('aborted', common.mustCall(function() {}));
+    res.on('aborted', common.mustCall());
   }));
 }));

test/parallel/test-http-invalidheaderfield.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const EventEmitter = require('events');
 const http = require('http');
@@ -28,7 +28,7 @@ server.listen(0, function() {
         port: server.address().port,
         headers: {'testing 123': 123}
       };
-      http.get(options, function() {});
+      http.get(options, common.noop);
     },
     function(err) {
       ee.emit('done');

test/parallel/test-http-pause-resume-one-end.js

@@ -22,6 +22,6 @@ server.listen(0, common.mustCall(function() {
       });
     }));
 
-    res.on('end', common.mustCall(function() {}));
+    res.on('end', common.mustCall());
   }));
 }));

test/parallel/test-http-set-timeout-server.js

@@ -31,7 +31,7 @@ test(function serverTimeout(cb) {
     // just do nothing, we should get a timeout event.
   });
   server.listen(common.mustCall(function() {
-    http.get({ port: server.address().port }).on('error', function() {});
+    http.get({ port: server.address().port }).on('error', common.noop);
   }));
   const s = server.setTimeout(50, function(socket) {
     caughtTimeout = true;
@@ -60,7 +60,7 @@ test(function serverRequestTimeout(cb) {
   server.listen(common.mustCall(function() {
     const port = server.address().port;
     const req = http.request({ port: port, method: 'POST' });
-    req.on('error', function() {});
+    req.on('error', common.noop);
     req.write('Hello');
     // req is in progress
   }));
@@ -83,7 +83,7 @@ test(function serverResponseTimeout(cb) {
   });
   server.listen(common.mustCall(function() {
     const port = server.address().port;
-    http.get({ port: port }).on('error', function() {});
+    http.get({ port: port }).on('error', common.noop);
   }));
 });
 
@@ -111,7 +111,7 @@ test(function serverRequestNotTimeoutAfterEnd(cb) {
   });
   server.listen(common.mustCall(function() {
     const port = server.address().port;
-    http.get({ port: port }).on('error', function() {});
+    http.get({ port: port }).on('error', common.noop);
   }));
 });
 

test/parallel/test-http-upgrade-server.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 const util = require('util');
@@ -16,7 +16,7 @@ function createTestServer() {
 }
 
 function testServer() {
-  http.Server.call(this, function() {});
+  http.Server.call(this, common.noop);
 
   this.on('connection', function() {
     requests_recv++;

test/parallel/test-https-close.js

@@ -31,7 +31,7 @@ server.on('connection', function(connection) {
 });
 
 function shutdown() {
-  server.close(common.mustCall(function() {}));
+  server.close(common.mustCall());
 
   for (const key in connections) {
     connections[key].destroy();

test/parallel/test-net-connect-options-ipv6.js

@@ -15,7 +15,7 @@ let localhostTries = 10;
 
 const server = net.createServer({allowHalfOpen: true}, function(socket) {
   socket.resume();
-  socket.on('end', common.mustCall(function() {}));
+  socket.on('end', common.mustCall());
   socket.end();
 });
 

test/parallel/test-net-connect-options.js

@@ -7,7 +7,7 @@ const server = net.createServer({
   allowHalfOpen: true
 }, common.mustCall(function(socket) {
   socket.resume();
-  socket.on('end', common.mustCall(function() {}));
+  socket.on('end', common.mustCall());
   socket.end();
 }));
 

test/parallel/test-net-listen-close-server-callback-is-not-function.js

@@ -4,7 +4,7 @@ const net = require('net');
 
 const server = net.createServer(common.mustNotCall());
 
-server.on('close', common.mustCall(function() {}));
+server.on('close', common.mustCall());
 
 server.listen(0, common.mustNotCall());
 

test/parallel/test-net-socket-destroy-twice.js

@@ -11,5 +11,5 @@ conn.on('error', common.mustCall(() => {
   conn.destroy();
 }));
 
-conn.on('close', common.mustCall(function() {}));
+conn.on('close', common.mustCall());
 server.close();

test/parallel/test-next-tick.js

@@ -4,15 +4,15 @@ const assert = require('assert');
 
 process.nextTick(common.mustCall(function() {
   process.nextTick(common.mustCall(function() {
-    process.nextTick(common.mustCall(function() {}));
+    process.nextTick(common.mustCall());
   }));
 }));
 
 setTimeout(common.mustCall(function() {
-  process.nextTick(common.mustCall(function() {}));
+  process.nextTick(common.mustCall());
 }), 50);
 
-process.nextTick(common.mustCall(function() {}));
+process.nextTick(common.mustCall());
 
 const obj = {};
 

test/parallel/test-process-next-tick.js

@@ -10,7 +10,7 @@ for (let i = 0; i < N; ++i) {
   process.nextTick(common.mustCall(cb));
 }
 
-process.on('uncaughtException', common.mustCall(function() {}, N));
+process.on('uncaughtException', common.mustCall(common.noop, N));
 
 process.on('exit', function() {
   process.removeAllListeners('uncaughtException');

test/parallel/test-promises-unhandled-rejections.js

@@ -164,7 +164,7 @@ asyncTest('Catching a promise rejection after setImmediate is not' +
   });
   _reject(e);
   setImmediate(function() {
-    promise.then(common.fail, function() {});
+    promise.then(common.fail, common.noop);
   });
 });
 
@@ -240,7 +240,7 @@ asyncTest(
   function(done) {
     const e = new Error();
     onUnhandledFail(done);
-    Promise.reject(e).then(common.fail, function() {});
+    Promise.reject(e).then(common.fail, common.noop);
   }
 );
 
@@ -252,7 +252,7 @@ asyncTest(
     onUnhandledFail(done);
     new Promise(function(_, reject) {
       reject(e);
-    }).then(common.fail, function() {});
+    }).then(common.fail, common.noop);
   }
 );
 
@@ -262,7 +262,7 @@ asyncTest('Attaching a promise catch in a process.nextTick is soon enough to' +
   onUnhandledFail(done);
   const promise = Promise.reject(e);
   process.nextTick(function() {
-    promise.then(common.fail, function() {});
+    promise.then(common.fail, common.noop);
   });
 });
 
@@ -274,7 +274,7 @@ asyncTest('Attaching a promise catch in a process.nextTick is soon enough to' +
     reject(e);
   });
   process.nextTick(function() {
-    promise.then(common.fail, function() {});
+    promise.then(common.fail, common.noop);
   });
 });
 
@@ -385,7 +385,7 @@ asyncTest('Catching the Promise.all() of a collection that includes a' +
           'rejected promise prevents unhandledRejection', function(done) {
   const e = new Error();
   onUnhandledFail(done);
-  Promise.all([Promise.reject(e)]).then(common.fail, function() {});
+  Promise.all([Promise.reject(e)]).then(common.fail, common.noop);
 });
 
 asyncTest(
@@ -401,7 +401,7 @@ asyncTest(
     });
     p = Promise.all([p]);
     process.nextTick(function() {
-      p.then(common.fail, function() {});
+      p.then(common.fail, common.noop);
     });
   }
 );
@@ -455,7 +455,7 @@ asyncTest('Waiting for some combination of process.nextTick + promise' +
     Promise.resolve().then(function() {
       process.nextTick(function() {
         Promise.resolve().then(function() {
-          a.catch(function() {});
+          a.catch(common.noop);
         });
       });
     });
@@ -474,7 +474,7 @@ asyncTest('Waiting for some combination of process.nextTick + promise' +
       Promise.resolve().then(function() {
         process.nextTick(function() {
           Promise.resolve().then(function() {
-            a.catch(function() {});
+            a.catch(common.noop);
           });
         });
       });
@@ -494,7 +494,7 @@ asyncTest('Waiting for some combination of process.nextTick + promise ' +
       Promise.resolve().then(function() {
         process.nextTick(function() {
           Promise.resolve().then(function() {
-            a.catch(function() {});
+            a.catch(common.noop);
           });
         });
       });
@@ -514,7 +514,7 @@ asyncTest('Waiting for some combination of promise microtasks + ' +
     process.nextTick(function() {
       Promise.resolve().then(function() {
         process.nextTick(function() {
-          a.catch(function() {});
+          a.catch(common.noop);
         });
       });
     });
@@ -535,7 +535,7 @@ asyncTest(
         process.nextTick(function() {
           Promise.resolve().then(function() {
             process.nextTick(function() {
-              a.catch(function() {});
+              a.catch(common.noop);
             });
           });
         });
@@ -556,7 +556,7 @@ asyncTest('Waiting for some combination of promise microtasks +' +
       process.nextTick(function() {
         Promise.resolve().then(function() {
           process.nextTick(function() {
-            a.catch(function() {});
+            a.catch(common.noop);
           });
         });
       });
@@ -575,7 +575,7 @@ asyncTest('setImmediate + promise microtasks is too late to attach a catch' +
   let p = Promise.reject(e);
   setImmediate(function() {
     Promise.resolve().then(function() {
-      p.catch(function() {});
+      p.catch(common.noop);
     });
   });
 });
@@ -592,7 +592,7 @@ asyncTest('setImmediate + promise microtasks is too late to attach a catch' +
       Promise.resolve().then(function() {
         Promise.resolve().then(function() {
           Promise.resolve().then(function() {
-            p.catch(function() {});
+            p.catch(common.noop);
           });
         });
       });
@@ -614,7 +614,7 @@ asyncTest('setImmediate + promise microtasks is too late to attach a catch' +
       Promise.resolve().then(function() {
         Promise.resolve().then(function() {
           Promise.resolve().then(function() {
-            p.catch(function() {});
+            p.catch(common.noop);
           });
         });
       });
@@ -682,7 +682,7 @@ asyncTest('Throwing an error inside a rejectionHandled handler goes to' +
   const p = Promise.reject(e);
   setTimeout(function() {
     try {
-      p.catch(function() {});
+      p.catch(common.noop);
     } catch (e) {
       done(new Error('fail'));
     }

test/parallel/test-querystring.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 // test using assert
@@ -72,7 +72,7 @@ extendedFunction.prototype = {a: 'b'};
 const qsWeirdObjects = [
   [{regexp: /./g}, 'regexp=', {'regexp': ''}],
   [{regexp: new RegExp('.', 'g')}, 'regexp=', {'regexp': ''}],
-  [{fn: function() {}}, 'fn=', {'fn': ''}],
+  [{fn: common.noop}, 'fn=', {'fn': ''}],
   [{fn: new Function('')}, 'fn=', {'fn': ''}],
   [{math: Math}, 'math=', {'math': ''}],
   [{e: extendedFunction}, 'e=', {'e': ''}],

test/parallel/test-readline-interface.js

@@ -11,10 +11,10 @@ function FakeInput() {
   EventEmitter.call(this);
 }
 inherits(FakeInput, EventEmitter);
-FakeInput.prototype.resume = function() {};
+FakeInput.prototype.resume = common.noop;
-FakeInput.prototype.pause = function() {};
+FakeInput.prototype.pause = common.noop;
-FakeInput.prototype.write = function() {};
+FakeInput.prototype.write = common.noop;
-FakeInput.prototype.end = function() {};
+FakeInput.prototype.end = common.noop;
 
 function isWarned(emitter) {
   for (const name in emitter) {

test/parallel/test-regress-GH-5051.js

@@ -1,11 +1,11 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const agent = require('http').globalAgent;
 
 // small stub just so we can call addRequest directly
 const req = {
-  getHeader: function() {}
+  getHeader: common.noop
 };
 
 agent.maxSockets = 0;

test/parallel/test-repl-.save.load.js

@@ -77,7 +77,7 @@ putIn.write = function(data) {
   // make sure I get a failed to load message and not some crazy error
   assert.strictEqual(data, 'Failed to load:' + loadFile + '\n');
   // eat me to avoid work
-  putIn.write = function() {};
+  putIn.write = common.noop;
 };
 putIn.run(['.load ' + loadFile]);
 
@@ -86,7 +86,7 @@ loadFile = common.tmpDir;
 putIn.write = function(data) {
   assert.strictEqual(data, 'Failed to load:' + loadFile +
                      ' is not a valid file\n');
-  putIn.write = function() {};
+  putIn.write = common.noop;
 };
 putIn.run(['.load ' + loadFile]);
 
@@ -102,7 +102,7 @@ putIn.write = function(data) {
   // make sure I get a failed to save message and not some other error
   assert.strictEqual(data, 'Failed to save:' + invalidFileName + '\n');
   // reset to no-op
-  putIn.write = function() {};
+  putIn.write = common.noop;
 };
 
 // save it to a file

test/parallel/test-repl-history-perm.js

@@ -19,7 +19,7 @@ const Duplex = require('stream').Duplex;
 // and mode 600.
 
 const stream = new Duplex();
-stream.pause = stream.resume = function() {};
+stream.pause = stream.resume = common.noop;
 // ends immediately
 stream._read = function() {
   this.push(null);

test/parallel/test-repl-mode.js

@@ -52,7 +52,7 @@ function testAutoMode() {
 
 function initRepl(mode) {
   const input = new Stream();
-  input.write = input.pause = input.resume = function() {};
+  input.write = input.pause = input.resume = common.noop;
   input.readable = true;
 
   const output = new Stream();

test/parallel/test-repl.js

@@ -200,7 +200,7 @@ function error_test() {
     { client: client_unix, send: 'blah()',
       expect: `1\n${prompt_unix}` },
     // Functions should not evaluate twice (#2773)
-    { client: client_unix, send: 'var I = [1,2,3,function() {}]; I.pop()',
+    { client: client_unix, send: 'var I = [1,2,3,common.noop]; I.pop()',
       expect: '[Function]' },
     // Multiline object
     { client: client_unix, send: '{ a: ',

test/parallel/test-signal-handler.js

@@ -9,7 +9,7 @@ if (common.isWindows) {
 
 console.log(`process.pid: ${process.pid}`);
 
-process.on('SIGUSR1', common.mustCall(function() {}));
+process.on('SIGUSR1', common.mustCall());
 
 process.on('SIGUSR1', common.mustCall(function() {
   setTimeout(function() {
@@ -31,5 +31,5 @@ setInterval(function() {
 // has been previously registered, and `process.listeners(SIGNAL).length === 1`
 process.on('SIGHUP', common.mustNotCall());
 process.removeAllListeners('SIGHUP');
-process.on('SIGHUP', common.mustCall(function() {}));
+process.on('SIGHUP', common.mustCall());
 process.kill(process.pid, 'SIGHUP');

test/parallel/test-stream-big-push.js

@@ -28,7 +28,7 @@ function _read() {
 
 r._read = common.mustCall(_read, 3);
 
-r.on('end', common.mustCall(function() {}));
+r.on('end', common.mustCall());
 
 // push some data in to start.
 // we've never gotten any read event at this point.

test/parallel/test-stream-end-paused.js

@@ -19,7 +19,7 @@ stream.on('data', function() {
 stream.pause();
 
 setTimeout(common.mustCall(function() {
-  stream.on('end', common.mustCall(function() {}));
+  stream.on('end', common.mustCall());
   stream.resume();
 }), 1);
 

test/parallel/test-stream-events-prepend.js

@@ -23,7 +23,7 @@ Readable.prototype._read = function() {
 };
 
 const w = new Writable();
-w.on('pipe', common.mustCall(function() {}));
+w.on('pipe', common.mustCall());
 
 const r = new Readable();
 r.pipe(w);

test/parallel/test-stream-pipe-after-end.js

@@ -42,11 +42,11 @@ const piper = new TestReadable();
 piper.read();
 
 setTimeout(common.mustCall(function() {
-  ender.on('end', common.mustCall(function() {}));
+  ender.on('end', common.mustCall());
   const c = ender.read();
   assert.strictEqual(c, null);
 
   const w = new TestWritable();
-  w.on('finish', common.mustCall(function() {}));
+  w.on('finish', common.mustCall());
   piper.pipe(w);
 }), 1);

test/parallel/test-stream-pipe-error-handling.js

@@ -79,11 +79,11 @@ const Stream = require('stream').Stream;
     }), 1);
   });
 
-  w.on('error', common.mustCall(function() {}));
+  w.on('error', common.mustCall());
-  w._write = function() {};
+  w._write = common.noop;
 
   r.pipe(w);
   // Removing some OTHER random listener should not do anything
-  w.removeListener('error', function() {});
+  w.removeListener('error', common.noop);
   removed = true;
 }

test/parallel/test-stream-readable-event.js

@@ -19,7 +19,7 @@ const Readable = require('stream').Readable;
   setTimeout(function() {
     // we're testing what we think we are
     assert(!r._readableState.reading);
-    r.on('readable', common.mustCall(function() {}));
+    r.on('readable', common.mustCall());
   }, 1);
 }
 
@@ -39,7 +39,7 @@ const Readable = require('stream').Readable;
   setTimeout(function() {
     // assert we're testing what we think we are
     assert(r._readableState.reading);
-    r.on('readable', common.mustCall(function() {}));
+    r.on('readable', common.mustCall());
   }, 1);
 }
 
@@ -59,6 +59,6 @@ const Readable = require('stream').Readable;
   setTimeout(function() {
     // assert we're testing what we think we are
     assert(!r._readableState.reading);
-    r.on('readable', common.mustCall(function() {}));
+    r.on('readable', common.mustCall());
   }, 1);
 }

test/parallel/test-stream-wrap.js

@@ -28,4 +28,4 @@ function testShutdown(callback) {
   req.handle.shutdown(req);
 }
 
-testShutdown(common.mustCall(function() {}));
+testShutdown(common.mustCall());

test/parallel/test-stream2-read-sync-stack.js

@@ -20,6 +20,6 @@ r.on('readable', function onReadable() {
   r.read(N * 2);
 });
 
-r.on('end', common.mustCall(function() {}));
+r.on('end', common.mustCall());
 
 r.read(0);

test/parallel/test-stream2-readable-legacy-drain.js

@@ -12,7 +12,7 @@ r._read = function(n) {
   return r.push(++reads === N ? null : Buffer.allocUnsafe(1));
 };
 
-r.on('end', common.mustCall(function() {}));
+r.on('end', common.mustCall());
 
 const w = new Stream();
 w.writable = true;
@@ -29,7 +29,7 @@ function drain() {
   w.emit('drain');
 }
 
-w.end = common.mustCall(function() {});
+w.end = common.mustCall();
 
 // Just for kicks, let's mess with the drain count.
 // This verifies that even if it gets negative in the

test/parallel/test-stream2-readable-non-empty-end.js

@@ -40,7 +40,7 @@ test.read(0);
 function next() {
   // now let's make 'end' happen
   test.removeListener('end', thrower);
-  test.on('end', common.mustCall(function() {}));
+  test.on('end', common.mustCall());
 
   // one to get the last byte
   let r = test.read();

test/parallel/test-stream2-readable-wrap-empty.js

@@ -5,13 +5,13 @@ const Readable = require('_stream_readable');
 const EE = require('events').EventEmitter;
 
 const oldStream = new EE();
-oldStream.pause = function() {};
+oldStream.pause = common.noop;
-oldStream.resume = function() {};
+oldStream.resume = common.noop;
 
 const newStream = new Readable().wrap(oldStream);
 
 newStream
-  .on('readable', function() {})
+  .on('readable', common.noop)
-  .on('end', common.mustCall(function() {}));
+  .on('end', common.mustCall());
 
 oldStream.emit('end');

test/parallel/test-stream2-readable-wrap.js

@@ -12,7 +12,7 @@ function runTest(highWaterMark, objectMode, produce) {
                            objectMode: objectMode });
   assert.strictEqual(r, r.wrap(old));
 
-  r.on('end', common.mustCall(function() {}));
+  r.on('end', common.mustCall());
 
   old.pause = function() {
     old.emit('pause');

test/parallel/test-stream2-writable.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const W = require('_stream_writable');
 const D = require('_stream_duplex');
 const assert = require('assert');
@@ -283,7 +283,7 @@ test('encoding should be ignored for buffers', function(t) {
 
 test('writables are not pipable', function(t) {
   const w = new W();
-  w._write = function() {};
+  w._write = common.noop;
   let gotError = false;
   w.on('error', function() {
     gotError = true;
@@ -295,8 +295,8 @@ test('writables are not pipable', function(t) {
 
 test('duplexes are pipable', function(t) {
   const d = new D();
-  d._read = function() {};
+  d._read = common.noop;
-  d._write = function() {};
+  d._write = common.noop;
   let gotError = false;
   d.on('error', function() {
     gotError = true;
@@ -308,7 +308,7 @@ test('duplexes are pipable', function(t) {
 
 test('end(chunk) two times is an error', function(t) {
   const w = new W();
-  w._write = function() {};
+  w._write = common.noop;
   let gotError = false;
   w.on('error', function(er) {
     gotError = true;

test/parallel/test-timers-uncaught-exception.js

@@ -10,7 +10,7 @@ setTimeout(common.mustCall(function() {
 }), 1);
 
 // ...but the second one should still run
-setTimeout(common.mustCall(function() {}), 1);
+setTimeout(common.mustCall(), 1);
 
 function uncaughtException(err) {
   assert.strictEqual(err.message, errorMsg);

test/parallel/test-timers-unref-call.js

@@ -1,11 +1,11 @@
 'use strict';
-require('../common');
+const common = require('../common');
 
 const Timer = process.binding('timer_wrap').Timer;
 Timer.now = function() { return ++Timer.now.ticks; };
 Timer.now.ticks = 0;
 
-const t = setInterval(function() {}, 1);
+const t = setInterval(common.noop, 1);
 const o = { _idleStart: 0, _idleTimeout: 1 };
 t.unref.call(o);
 

test/parallel/test-timers-unref-remove-other-unref-timers.js

@@ -29,4 +29,4 @@ timers.enroll(foo, 50);
 timers._unrefActive(foo);
 
 // Keep the process open.
-setTimeout(function() {}, 100);
+setTimeout(common.noop, 100);

test/parallel/test-timers-unref.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 let interval_fired = false;
@@ -13,11 +13,11 @@ const LONG_TIME = 10 * 1000;
 const SHORT_TIME = 100;
 
 assert.doesNotThrow(function() {
-  setTimeout(function() {}, 10).unref().ref().unref();
+  setTimeout(common.noop, 10).unref().ref().unref();
 }, 'ref and unref are chainable');
 
 assert.doesNotThrow(function() {
-  setInterval(function() {}, 10).unref().ref().unref();
+  setInterval(common.noop, 10).unref().ref().unref();
 }, 'ref and unref are chainable');
 
 setInterval(function() {
@@ -56,7 +56,7 @@ setInterval(function() {
 
 // Should not assert on args.Holder()->InternalFieldCount() > 0. See #4261.
 {
-  const t = setInterval(function() {}, 1);
+  const t = setInterval(common.noop, 1);
   process.nextTick(t.unref.bind({}));
   process.nextTick(t.unref.bind(t));
 }

test/parallel/test-timers-zero-timeout.js

@@ -5,7 +5,7 @@ const assert = require('assert');
 // https://github.com/joyent/node/issues/2079 - zero timeout drops extra args
 {
   setTimeout(common.mustCall(f), 0, 'foo', 'bar', 'baz');
-  setTimeout(function() {}, 0);
+  setTimeout(common.noop, 0);
 
   function f(a, b, c) {
     assert.strictEqual(a, 'foo');

test/parallel/test-timers.js

@@ -56,5 +56,5 @@ setTimeout(common.mustCall(function() {
 }), 2);
 
 // Test 10 ms timeout separately.
-setTimeout(common.mustCall(function() {}), 10);
+setTimeout(common.mustCall(), 10);
 setInterval(common.mustCall(function() { clearInterval(this); }), 10);

test/parallel/test-tls-cert-regression.js

@@ -42,5 +42,5 @@ function test(cert, key, cb) {
 }
 
 test(cert, key, common.mustCall(function() {
-  test(Buffer.from(cert), Buffer.from(key), common.mustCall(function() {}));
+  test(Buffer.from(cert), Buffer.from(key), common.mustCall());
 }));

test/parallel/test-tls-connect-simple.js

@@ -18,8 +18,8 @@ const options = {
 
 const server = tls.Server(options, common.mustCall(function(socket) {
   if (++serverConnected === 2) {
-    server.close(common.mustCall(function() {}));
+    server.close(common.mustCall());
-    server.on('close', common.mustCall(function() {}));
+    server.on('close', common.mustCall());
   }
 }, 2));
 

test/parallel/test-tls-connect.js

@@ -20,7 +20,7 @@ const path = require('path');
   const options = {cert: cert, key: key, port: common.PORT};
   const conn = tls.connect(options, common.fail);
 
-  conn.on('error', common.mustCall(function() {}));
+  conn.on('error', common.mustCall());
 }
 
 // SSL_accept/SSL_connect error handling
@@ -37,5 +37,5 @@ const path = require('path');
     assert.ok(false); // callback should never be executed
   });
 
-  conn.on('error', common.mustCall(function() {}));
+  conn.on('error', common.mustCall());
 }

test/parallel/test-tls-delayed-attach-error.js

@@ -23,7 +23,7 @@ const server = net.createServer(common.mustCall(function(c) {
       secureContext: tls.createSecureContext(options)
     });
 
-    s.on('_tlsError', common.mustCall(function() {}));
+    s.on('_tlsError', common.mustCall());
 
     s.on('close', function() {
       server.close();

test/parallel/test-tls-env-extra-ca.js

@@ -16,7 +16,7 @@ const fs = require('fs');
 if (process.env.CHILD) {
   const copts = {
     port: process.env.PORT,
-    checkServerIdentity: function() {},
+    checkServerIdentity: common.noop,
   };
   const client = tls.connect(copts, function() {
     client.end('hi');

test/parallel/test-tls-invoke-queued.js

@@ -21,7 +21,7 @@ const server = tls.createServer({
     c._write('world!', null, function() {
       c.destroy();
     });
-    c._write(' gosh', null, function() {});
+    c._write(' gosh', null, common.noop);
   });
 
   server.close();

test/parallel/test-tls-legacy-onselect.js

@@ -10,7 +10,7 @@ const net = require('net');
 
 const server = net.Server(common.mustCall(function(raw) {
   const pair = tls.createSecurePair(null, true, false, false);
-  pair.on('error', function() {});
+  pair.on('error', common.noop);
   pair.ssl.setSNICallback(common.mustCall(function() {
     raw.destroy();
     server.close();

test/parallel/test-tls-passphrase.js

@@ -39,14 +39,14 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'passphrase',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: rawKey,
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -54,7 +54,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   // Buffer[]
   tls.connect({
@@ -63,14 +63,14 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'passphrase',
     cert: [cert],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [rawKey],
     cert: [cert],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -78,7 +78,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: [cert],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   // string
   tls.connect({
@@ -87,14 +87,14 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'passphrase',
     cert: cert.toString(),
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: rawKey.toString(),
     cert: cert.toString(),
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -102,7 +102,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: cert.toString(),
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   // String[]
   tls.connect({
@@ -111,14 +111,14 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'passphrase',
     cert: [cert.toString()],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [rawKey.toString()],
     cert: [cert.toString()],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -126,7 +126,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: [cert.toString()],
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   // Object[]
   tls.connect({
@@ -134,7 +134,7 @@ server.listen(0, common.mustCall(function() {
     key: [{pem: passKey, passphrase: 'passphrase'}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -142,7 +142,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -150,28 +150,28 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'passphrase',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [{pem: passKey.toString(), passphrase: 'passphrase'}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [{pem: rawKey, passphrase: 'ignored'}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [{pem: rawKey.toString(), passphrase: 'ignored'}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -179,7 +179,7 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
@@ -187,21 +187,21 @@ server.listen(0, common.mustCall(function() {
     passphrase: 'ignored',
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [{pem: rawKey}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 
   tls.connect({
     port: this.address().port,
     key: [{pem: rawKey.toString()}],
     cert: cert,
     rejectUnauthorized: false
-  }, common.mustCall(function() {}));
+  }, common.mustCall());
 })).unref();
 
 const errMessagePassword = /bad password read/;

test/parallel/test-url.js

@@ -1,6 +1,6 @@
 /* eslint-disable max-len */
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 const url = require('url');
@@ -1684,7 +1684,7 @@ const throws = [
   true,
   false,
   0,
-  function() {}
+  common.noop
 ];
 for (let i = 0; i < throws.length; i++) {
   assert.throws(function() { url.format(throws[i]); }, TypeError);

test/parallel/test-util.js

@@ -12,7 +12,7 @@ assert.strictEqual(true, util.isArray(new Array(5)));
 assert.strictEqual(true, util.isArray(new Array('with', 'some', 'entries')));
 assert.strictEqual(true, util.isArray(context('Array')()));
 assert.strictEqual(false, util.isArray({}));
-assert.strictEqual(false, util.isArray({ push: function() {} }));
+assert.strictEqual(false, util.isArray({ push: common.noop }));
 assert.strictEqual(false, util.isArray(/regexp/));
 assert.strictEqual(false, util.isArray(new Error()));
 assert.strictEqual(false, util.isArray(Object.create(Array.prototype)));
@@ -61,7 +61,7 @@ assert.strictEqual(false, util.isPrimitive(new Error()));
 assert.strictEqual(false, util.isPrimitive(new Date()));
 assert.strictEqual(false, util.isPrimitive([]));
 assert.strictEqual(false, util.isPrimitive(/regexp/));
-assert.strictEqual(false, util.isPrimitive(function() {}));
+assert.strictEqual(false, util.isPrimitive(common.noop));
 assert.strictEqual(false, util.isPrimitive(new Number(1)));
 assert.strictEqual(false, util.isPrimitive(new String('bla')));
 assert.strictEqual(false, util.isPrimitive(new Boolean(true)));
@@ -117,7 +117,7 @@ assert.strictEqual(util.isSymbol(), false);
 assert.strictEqual(util.isSymbol('string'), false);
 
 assert.strictEqual(util.isFunction(() => {}), true);
-assert.strictEqual(util.isFunction(function() {}), true);
+assert.strictEqual(util.isFunction(common.noop), true);
 assert.strictEqual(util.isFunction(), false);
 assert.strictEqual(util.isFunction('string'), false);
 

test/parallel/test-vm-function-declaration.js

@@ -7,7 +7,7 @@ const o = vm.createContext({ console: console });
 
 // Function declaration and expression should both be copied to the
 // sandboxed context.
-let code = 'var a = function() {};\n';
+let code = 'var a = function () {};\n';
 code += 'function b(){}\n';
 
 // Grab the global b function as the completion value, to ensure that

test/parallel/test-zlib-close-after-write.js

@@ -5,5 +5,5 @@ const zlib = require('zlib');
 zlib.gzip('hello', common.mustCall(function(err, out) {
   const unzip = zlib.createGunzip();
   unzip.write(out);
-  unzip.close(common.mustCall(function() {}));
+  unzip.close(common.mustCall());
 }));

test/parallel/test-zlib-write-after-close.js

@@ -5,6 +5,6 @@ const zlib = require('zlib');
 
 zlib.gzip('hello', common.mustCall(function(err, out) {
   const unzip = zlib.createGunzip();
-  unzip.close(common.mustCall(function() {}));
+  unzip.close(common.mustCall());
   assert.throws(() => unzip.write(out), /^Error: zlib binding closed$/);
 }));

test/parallel/test-zlib-zero-byte.js

@@ -13,6 +13,6 @@ gz.on('data', function(c) {
 gz.on('end', common.mustCall(function() {
   assert.strictEqual(received, 20);
 }));
-gz.on('finish', common.mustCall(function() {}));
+gz.on('finish', common.mustCall());
 gz.write(emptyBuffer);
 gz.end();

test/pummel/test-http-client-reconnect-bug.js

@@ -11,7 +11,7 @@ server.on('listening', common.mustCall(function() {
   const client = http.createClient(common.PORT);
 
   client.on('error', common.mustCall(function(err) {}));
-  client.on('end', common.mustCall(function() {}));
+  client.on('end', common.mustCall());
 
   const request = client.request('GET', '/', {'host': 'localhost'});
   request.end();

test/pummel/test-net-connect-memleak.js

@@ -10,7 +10,7 @@ assert.strictEqual(
   'function',
   'Run this test with --expose-gc'
 );
-net.createServer(function() {}).listen(common.PORT);
+net.createServer(common.noop).listen(common.PORT);
 
 let before = 0;
 {

test/pummel/test-stream2-basic.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const R = require('_stream_readable');
 const assert = require('assert');
 
@@ -451,7 +451,7 @@ test('adding readable triggers data flow', function(t) {
 
 test('chainable', function(t) {
   const r = new R();
-  r._read = function() {};
+  r._read = common.noop;
   const r2 = r.setEncoding('utf8').pause().resume().pause();
   t.equal(r, r2);
   t.end();

test/sequential/test-child-process-pass-fd.js

@@ -45,7 +45,7 @@ if (process.argv[2] !== 'child') {
   // the only thing keeping this worker alive will be IPC. This is important,
   // because it means a worker with no parent will have no referenced handles,
   // thus no work to do, and will exit immediately, preventing process leaks.
-  process.on('message', function() {});
+  process.on('message', common.noop);
 
   const server = net.createServer((c) => {
     process.once('message', function(msg) {

test/sequential/test-fs-watch.js

@@ -117,7 +117,7 @@ assert.throws(function() {
 oldhandle.close(); // clean up
 
 assert.throws(function() {
-  const w = fs.watchFile(__filename, {persistent: false}, function() {});
+  const w = fs.watchFile(__filename, {persistent: false}, common.noop);
   oldhandle = w._handle;
   w._handle = { stop: w._handle.stop };
   w.stop();

test/sequential/test-https-set-timeout-server.js

@@ -48,7 +48,7 @@ test(function serverTimeout(cb) {
     https.get({
       port: this.address().port,
       rejectUnauthorized: false
-    }).on('error', function() {});
+    }).on('error', common.noop);
   }));
 });
 
@@ -69,7 +69,7 @@ test(function serverRequestTimeout(cb) {
       method: 'POST',
       rejectUnauthorized: false
     });
-    req.on('error', function() {});
+    req.on('error', common.noop);
     req.write('Hello');
     // req is in progress
   });
@@ -90,7 +90,7 @@ test(function serverResponseTimeout(cb) {
     https.get({
       port: this.address().port,
       rejectUnauthorized: false
-    }).on('error', function() {});
+    }).on('error', common.noop);
   });
 });
 
@@ -110,7 +110,7 @@ test(function serverRequestNotTimeoutAfterEnd(cb) {
     https.get({
       port: this.address().port,
       rejectUnauthorized: false
-    }).on('error', function() {});
+    }).on('error', common.noop);
   });
 });