From 7f38f0a422dbb6ab6632fd664318dd435a35eafb Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Wed, 18 Dec 2019 19:58:49 +0100
Subject: [PATCH] readline: set null as callback return in case there's no
 error

The cursor move functions accept a callback. It was possible that
`undefined` was returned in case there was no error instead of null.
---
 lib/readline.js                    |  8 ++++----
 test/parallel/test-readline-csi.js | 16 ++++++++++++----
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/lib/readline.js b/lib/readline.js
index 7c8488122d5bb4..3129f1617604f4 100644
--- a/lib/readline.js
+++ b/lib/readline.js
@@ -1198,7 +1198,7 @@ function cursorTo(stream, x, y, callback) {
 
   if (stream == null || (typeof x !== 'number' && typeof y !== 'number')) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1219,7 +1219,7 @@ function moveCursor(stream, dx, dy, callback) {
 
   if (stream == null || !(dx || dy)) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1253,7 +1253,7 @@ function clearLine(stream, dir, callback) {
 
   if (stream === null || stream === undefined) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
@@ -1275,7 +1275,7 @@ function clearScreenDown(stream, callback) {
 
   if (stream === null || stream === undefined) {
     if (typeof callback === 'function')
-      process.nextTick(callback);
+      process.nextTick(callback, null);
     return true;
   }
 
diff --git a/test/parallel/test-readline-csi.js b/test/parallel/test-readline-csi.js
index 53b07d7bd939fd..346f1cbad12db1 100644
--- a/test/parallel/test-readline-csi.js
+++ b/test/parallel/test-readline-csi.js
@@ -39,7 +39,9 @@ assert.throws(() => {
 }, /ERR_INVALID_CALLBACK/);
 
 // Verify that clearScreenDown() does not throw on null or undefined stream.
-assert.strictEqual(readline.clearScreenDown(null, common.mustCall()), true);
+assert.strictEqual(readline.clearScreenDown(null, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.clearScreenDown(undefined, common.mustCall()),
                    true);
 
@@ -67,7 +69,9 @@ assert.throws(() => {
 // Verify that clearLine() does not throw on null or undefined stream.
 assert.strictEqual(readline.clearLine(null, 0), true);
 assert.strictEqual(readline.clearLine(undefined, 0), true);
-assert.strictEqual(readline.clearLine(null, 0, common.mustCall()), true);
+assert.strictEqual(readline.clearLine(null, 0, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.clearLine(undefined, 0, common.mustCall()), true);
 
 // Nothing is written when moveCursor 0, 0
@@ -101,7 +105,9 @@ assert.throws(() => {
 // Verify that moveCursor() does not throw on null or undefined stream.
 assert.strictEqual(readline.moveCursor(null, 1, 1), true);
 assert.strictEqual(readline.moveCursor(undefined, 1, 1), true);
-assert.strictEqual(readline.moveCursor(null, 1, 1, common.mustCall()), true);
+assert.strictEqual(readline.moveCursor(null, 1, 1, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 assert.strictEqual(readline.moveCursor(undefined, 1, 1, common.mustCall()),
                    true);
 
@@ -109,7 +115,9 @@ assert.strictEqual(readline.moveCursor(undefined, 1, 1, common.mustCall()),
 assert.strictEqual(readline.cursorTo(null), true);
 assert.strictEqual(readline.cursorTo(), true);
 assert.strictEqual(readline.cursorTo(null, 1, 1, common.mustCall()), true);
-assert.strictEqual(readline.cursorTo(undefined, 1, 1, common.mustCall()), true);
+assert.strictEqual(readline.cursorTo(undefined, 1, 1, common.mustCall((err) => {
+  assert.strictEqual(err, null);
+})), true);
 
 writable.data = '';
 assert.strictEqual(readline.cursorTo(writable, 'a'), true);