util: make util.debuglog() consistent with doc

Previous realization produces some false positive and false negative
results due to:

* conflicts between unescaped user input and RegExp special characters;

* conflicts between parsing with `\b` RegExp symbol and non
  alphanumeric characters in section names.

The doc does not mention any such restrictions.

PR-URL: nodejs#13841
Fixes: nodejs#13728
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/util.js

@@ -147,11 +147,13 @@ exports.deprecate = internalUtil.deprecate;
 var debugs = {};
 var debugEnviron;
 exports.debuglog = function(set) {
-  if (debugEnviron === undefined)
-    debugEnviron = process.env.NODE_DEBUG || '';
+  if (debugEnviron === undefined) {
+    debugEnviron = new Set(
+      (process.env.NODE_DEBUG || '').split(',').map((s) => s.toUpperCase()));
+  }
   set = set.toUpperCase();
   if (!debugs[set]) {
-    if (new RegExp(`\\b${set}\\b`, 'i').test(debugEnviron)) {
+    if (debugEnviron.has(set)) {
       var pid = process.pid;
       debugs[set] = function() {
         var msg = exports.format.apply(exports, arguments);

test/sequential/test-util-debug.js

@@ -23,34 +23,42 @@
 const common = require('../common');
 const assert = require('assert');
 
-if (process.argv[2] === 'child')
-  child();
+const [, , modeArgv, sectionArgv] = process.argv;
+
+if (modeArgv === 'child')
+  child(sectionArgv);
 else
   parent();
 
 function parent() {
-  test('foo,tud,bar', true);
-  test('foo,tud', true);
-  test('tud,bar', true);
-  test('tud', true);
-  test('foo,bar', false);
-  test('', false);
+  test('foo,tud,bar', true, 'tud');
+  test('foo,tud', true, 'tud');
+  test('tud,bar', true, 'tud');
+  test('tud', true, 'tud');
+  test('foo,bar', false, 'tud');
+  test('', false, 'tud');
+
+  test('###', true, '###');
+  test('hi:)', true, 'hi:)');
+  test('f$oo', true, 'f$oo');
+  test('f$oo', false, 'f.oo');
+  test('no-bar-at-all', false, 'bar');
 }
 
-function test(environ, shouldWrite) {
+function test(environ, shouldWrite, section) {
   let expectErr = '';
-  if (shouldWrite) {
-    expectErr = 'TUD %PID%: this { is: \'a\' } /debugging/\n' +
-                'TUD %PID%: number=1234 string=asdf obj={"foo":"bar"}\n';
-  }
   const expectOut = 'ok\n';
 
   const spawn = require('child_process').spawn;
-  const child = spawn(process.execPath, [__filename, 'child'], {
+  const child = spawn(process.execPath, [__filename, 'child', section], {
     env: Object.assign(process.env, { NODE_DEBUG: environ })
   });
 
-  expectErr = expectErr.split('%PID%').join(child.pid);
+  if (shouldWrite) {
+    expectErr =
+      `${section.toUpperCase()} ${child.pid}: this { is: 'a' } /debugging/\n${
+         section.toUpperCase()} ${child.pid}: num=1 str=a obj={"foo":"bar"}\n`;
+  }
 
   let err = '';
   child.stderr.setEncoding('utf8');
@@ -72,10 +80,10 @@ function test(environ, shouldWrite) {
 }
 
 
-function child() {
+function child(section) {
   const util = require('util');
-  const debug = util.debuglog('tud');
+  const debug = util.debuglog(section);
   debug('this', { is: 'a' }, /debugging/);
-  debug('number=%d string=%s obj=%j', 1234, 'asdf', { foo: 'bar' });
+  debug('num=%d str=%s obj=%j', 1, 'a', { foo: 'bar' });
   console.log('ok');
 }