From 21b05cd6cd66afb86145bc0a22e571dd5842112e Mon Sep 17 00:00:00 2001
From: Ali Ijaz Sheikh <ofrobots@google.com>
Date: Wed, 25 Jan 2017 16:26:23 -0800
Subject: [PATCH] test: fix timing sensitivity in debugger test

test-debugger-util-regression.js was sensitive to timing, which seems
to have changed enough with V8 5.7 to cause this test to fail. Fix the
test to ensure we take debugger steps only at stable states instead of
erroneously taking a step on a partially complete buffer.

PR-URL: https://github.com/nodejs/node/pull/11008
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 test/parallel/test-debugger-util-regression.js | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/test/parallel/test-debugger-util-regression.js b/test/parallel/test-debugger-util-regression.js
index 07e5254581..fa5b9e8b0a 100644
--- a/test/parallel/test-debugger-util-regression.js
+++ b/test/parallel/test-debugger-util-regression.js
@@ -4,6 +4,8 @@ const path = require('path');
 const spawn = require('child_process').spawn;
 const assert = require('assert');
 
+const DELAY = common.platformTimeout(200);
+
 const fixture = path.join(
   common.fixturesDir,
   'debugger-util-regression-fixture.js'
@@ -21,12 +23,16 @@ proc.stderr.setEncoding('utf8');
 
 let stdout = '';
 let stderr = '';
+proc.stdout.on('data', (data) => stdout += data);
+proc.stderr.on('data', (data) => stderr += data);
 
 let nextCount = 0;
 let exit = false;
 
-proc.stdout.on('data', (data) => {
-  stdout += data;
+// We look at output periodically. We don't do this in the on('data') as we
+// may end up processing partial output. Processing periodically ensures that
+// the debugger is in a stable state before we take the next step.
+const timer = setInterval(() => {
   if (stdout.includes('> 1') && nextCount < 1 ||
       stdout.includes('> 2') && nextCount < 2 ||
       stdout.includes('> 3') && nextCount < 3 ||
@@ -36,14 +42,14 @@ proc.stdout.on('data', (data) => {
   } else if (!exit && (stdout.includes('< { a: \'b\' }'))) {
     exit = true;
     proc.stdin.write('.exit\n');
+    // We can cancel the timer and terminate normally.
+    clearInterval(timer);
   } else if (stdout.includes('program terminated')) {
     // Catch edge case present in v4.x
     // process will terminate after call to util.inspect
     common.fail('the program should not terminate');
   }
-});
-
-proc.stderr.on('data', (data) => stderr += data);
+}, DELAY);
 
 process.on('exit', (code) => {
   assert.strictEqual(code, 0, 'the program should exit cleanly');