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>

1 files changed, 4 insertions, 4 deletions

diff --git a/test/parallel/test-stream-readable-needReadable.js b/test/parallel/test-stream-readable-needReadable.js
index be397dc5dc..dba188c572 100644
--- a/test/parallel/test-stream-readable-needReadable.js
+++ b/test/parallel/test-stream-readable-needReadable.js
@@ -4,7 +4,7 @@ const assert = require('assert');
 const Readable = require('stream').Readable;
 
 const readable = new Readable({
-  read: () => {}
+  read: common.noop
 });
 
 // Initialized to false.
@@ -28,7 +28,7 @@ readable.on('end', common.mustCall(() => {
 }));
 
 const asyncReadable = new Readable({
-  read: () => {}
+  read: common.noop
 });
 
 asyncReadable.on('readable', common.mustCall(() => {
@@ -51,7 +51,7 @@ process.nextTick(common.mustCall(() => {
 }));
 
 const flowing = new Readable({
-  read: () => {}
+  read: common.noop
 });
 
 // Notice this must be above the on('data') call.
@@ -69,7 +69,7 @@ flowing.on('data', common.mustCall(function(data) {
 }, 3));
 
 const slowProducer = new Readable({
-  read: () => {}
+  read: common.noop
 });
 
 slowProducer.on('readable', common.mustCall(() => {