From 54a57880e41d750509320c4dad19deccd0b6afd2 Mon Sep 17 00:00:00 2001
From: Juerg B <44573692+juergba@users.noreply.github.com>
Date: Sat, 31 Jul 2021 14:40:10 +0200
Subject: [PATCH] Add new option "node-option" (#4691)

---
 bin/mocha                                   | 45 +++++++++------------
 docs/index.md                               | 19 ++++++---
 example/config/.mocharc.js                  |  1 +
 example/config/.mocharc.yml                 |  2 +
 lib/cli/cli.js                              |  5 ++-
 lib/cli/node-flags.js                       |  7 +---
 lib/cli/run-option-metadata.js              |  2 +
 lib/cli/run.js                              |  4 ++
 test/integration/options/node-flags.spec.js | 16 ++++++++
 test/integration/options/timeout.spec.js    | 17 +++++++-
 test/node-unit/cli/node-flags.spec.js       |  8 +---
 11 files changed, 79 insertions(+), 47 deletions(-)

diff --git a/bin/mocha b/bin/mocha
index 79d35562d4..fb58e65fcd 100755
--- a/bin/mocha
+++ b/bin/mocha
@@ -10,7 +10,6 @@
  * @private
  */
 
-const {deprecate} = require('../lib/utils');
 const {loadOptions} = require('../lib/cli/options');
 const {
   unparseNodeFlags,
@@ -23,6 +22,7 @@ const {aliases} = require('../lib/cli/run-option-metadata');
 
 const mochaArgs = {};
 const nodeArgs = {};
+let hasInspect = false;
 
 const opts = loadOptions(process.argv.slice(2));
 debug('loaded opts', opts);
@@ -59,48 +59,39 @@ Object.keys(opts).forEach(opt => {
 
 // disable 'timeout' for debugFlags
 Object.keys(nodeArgs).forEach(opt => disableTimeouts(opt));
+mochaArgs['node-option'] &&
+  mochaArgs['node-option'].forEach(opt => disableTimeouts(opt));
 
 // Native debugger handling
 // see https://nodejs.org/api/debugger.html#debugger_debugger
-// look for 'inspect' or 'debug' that would launch this debugger,
+// look for 'inspect' that would launch this debugger,
 // remove it from Mocha's opts and prepend it to Node's opts.
 // A deprecation warning will be printed by node, if applicable.
 // (mochaArgs._ are "positional" arguments, not prefixed with - or --)
 if (mochaArgs._) {
-  const i = mochaArgs._.findIndex(val => val === 'inspect' || val === 'debug');
+  const i = mochaArgs._.findIndex(val => val === 'inspect');
   if (i > -1) {
-    const [command] = mochaArgs._.splice(i, 1);
+    mochaArgs._.splice(i, 1);
     disableTimeouts('inspect');
-    nodeArgs._ = [command];
+    hasInspect = true;
   }
 }
 
-// historical
-if (nodeArgs.gc) {
-  deprecate(
-    '"-gc" is deprecated and will be removed from a future version of Mocha.  Use "--gc-global" instead.'
-  );
-  nodeArgs['gc-global'] = nodeArgs.gc;
-  delete nodeArgs.gc;
-}
-
-// --require/-r is treated as Mocha flag except when 'esm' is preloaded
-if (mochaArgs.require && mochaArgs.require.includes('esm')) {
-  nodeArgs.require = ['esm'];
-  mochaArgs.require = mochaArgs.require.filter(mod => mod !== 'esm');
-  if (!mochaArgs.require.length) {
-    delete mochaArgs.require;
-  }
-}
-
-if (Object.keys(nodeArgs).length) {
+if (mochaArgs['node-option'] || Object.keys(nodeArgs).length || hasInspect) {
   const {spawn} = require('child_process');
   const mochaPath = require.resolve('../lib/cli/cli.js');
 
-  debug('final node args', nodeArgs);
+  const nodeArgv =
+    (mochaArgs['node-option'] && mochaArgs['node-option'].map(v => '--' + v)) ||
+    unparseNodeFlags(nodeArgs);
+
+  if (hasInspect) nodeArgv.unshift('inspect');
+  delete mochaArgs['node-option'];
+
+  debug('final node argv', nodeArgv);
 
   const args = [].concat(
-    unparseNodeFlags(nodeArgs),
+    nodeArgv,
     mochaPath,
     unparse(mochaArgs, {alias: aliases})
   );
@@ -147,5 +138,5 @@ if (Object.keys(nodeArgs).length) {
   });
 } else {
   debug('running Mocha in-process');
-  require('../lib/cli/cli').main(unparse(mochaArgs, {alias: aliases}));
+  require('../lib/cli/cli').main([], mochaArgs);
 }
diff --git a/docs/index.md b/docs/index.md
index 12b4b18955..86497d0ab1 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -876,9 +876,7 @@ Use this option to have Mocha check for global variables that are leaked while r
 
 ### `--dry-run`
 
-> _New in v9.0.0._
-
-Report tests without executing any of them, neither tests nor hooks.
+> _New in v9.0.0._ Report tests without executing any of them, neither tests nor hooks.
 
 ### `--exit`
 
@@ -1015,6 +1013,15 @@ Specify an explicit path to a [configuration file](#configuring-mocha-nodejs).
 
 By default, Mocha will search for a config file if `--config` is not specified; use `--no-config` to suppress this behavior.
 
+### `--node-option <name>, -n <name>`
+
+> _New in v9.1.0._
+
+For Node.js and V8 options. Mocha forwards these options to Node.js by spawning a new child-process.<br>
+The options are set without leading dashes `--`, e.g. `-n require=foo -n unhandled-rejections=strict`
+
+Can also be specified as a comma-delimited list: `-n require=foo,unhandled-rejections=strict`
+
 ### `--opts <path>`
 
 > _Removed in v8.0.0. Please use [configuration file](#configuring-mocha-nodejs) instead._
@@ -1159,8 +1166,6 @@ Requires either `--grep` or `--fgrep` (but not both).
 
 ### `--inspect, --inspect-brk, inspect`
 
-> _BREAKING CHANGE in v7.0.0; `--debug` / `--debug-brk` are removed and `debug` is deprecated._
-
 Enables Node.js' inspector.
 
 Use `--inspect` / `--inspect-brk` to launch the V8 inspector for use with Chrome Dev Tools.
@@ -1209,6 +1214,8 @@ These flags vary depending on your version of Node.js.
 
 `node` flags can be defined in Mocha's [configuration](#configuring-mocha-nodejs).
 
+> _New in v9.1.0._ You can also pass `node` flags to Node.js using [`--node-option`](#-node-option-name-n-name).
+
 ### `--enable-source-maps`
 
 > _New in Node.js v12.12.0_
@@ -1228,6 +1235,8 @@ Prepend `--v8-` to any flag listed in the output of `node --v8-options` (excludi
 
 V8 flags can be defined in Mocha's [configuration](#configuring-mocha-nodejs).
 
+> _New in v9.1.0._ You can also pass V8 flags (without `--v8-`) to Node.js using [`--node-option`](#-node-option-name-n-name).
+
 ## Parallel Tests
 
 > _New in v.8.0.0._
diff --git a/example/config/.mocharc.js b/example/config/.mocharc.js
index 235f6e0b86..bdd89e769f 100644
--- a/example/config/.mocharc.js
+++ b/example/config/.mocharc.js
@@ -26,6 +26,7 @@ module.exports = {
   'inline-diffs': false,
   // invert: false, // needs to be used with grep or fgrep
   jobs: 1,
+  'node-option': ['unhandled-rejections=strict'], // without leading "--", also V8 flags
   package: './package.json',
   parallel: false,
   recursive: false,
diff --git a/example/config/.mocharc.yml b/example/config/.mocharc.yml
index 0172f7cd40..4ba30dff22 100644
--- a/example/config/.mocharc.yml
+++ b/example/config/.mocharc.yml
@@ -29,6 +29,8 @@ inline-diffs: false
 # needs to be used with grep or fgrep
 # invert: false
 jobs: 1
+node-option:
+  - 'unhandled-rejections=strict' # without leading "--", also V8 flags
 package: './package.json'
 parallel: false
 recursive: false
diff --git a/lib/cli/cli.js b/lib/cli/cli.js
index f3b780cf9d..977a341564 100755
--- a/lib/cli/cli.js
+++ b/lib/cli/cli.js
@@ -33,8 +33,9 @@ const {cwd} = require('../utils');
  * @public
  * @summary Mocha's main command-line entry-point.
  * @param {string[]} argv - Array of arguments to parse, or by default the lovely `process.argv.slice(2)`
+ * @param {object} [mochaArgs] - Object of already parsed Mocha arguments (by bin/mocha)
  */
-exports.main = (argv = process.argv.slice(2)) => {
+exports.main = (argv = process.argv.slice(2), mochaArgs) => {
   debug('entered main with raw args', argv);
   // ensure we can require() from current working directory
   if (typeof module.paths !== 'undefined') {
@@ -43,7 +44,7 @@ exports.main = (argv = process.argv.slice(2)) => {
 
   Error.stackTraceLimit = Infinity; // configurable via --stack-trace-limit?
 
-  var args = loadOptions(argv);
+  var args = mochaArgs || loadOptions(argv);
 
   yargs()
     .scriptName('mocha')
diff --git a/lib/cli/node-flags.js b/lib/cli/node-flags.js
index 1203ad2ea8..25ca2669c5 100644
--- a/lib/cli/node-flags.js
+++ b/lib/cli/node-flags.js
@@ -49,7 +49,7 @@ exports.isNodeFlag = (flag, bareword = true) => {
     // and also any V8 flags with `--v8-` prefix
     (!isMochaFlag(flag) && nodeFlags && nodeFlags.has(flag)) ||
     debugFlags.has(flag) ||
-    /(?:preserve-symlinks(?:-main)?|harmony(?:[_-]|$)|(?:trace[_-].+$)|gc(?:[_-]global)?$|es[_-]staging$|use[_-]strict$|v8[_-](?!options).+?$)/.test(
+    /(?:preserve-symlinks(?:-main)?|harmony(?:[_-]|$)|(?:trace[_-].+$)|gc[_-]global$|es[_-]staging$|use[_-]strict$|v8[_-](?!options).+?$)/.test(
       flag
     )
   );
@@ -67,7 +67,6 @@ exports.impliesNoTimeouts = flag => debugFlags.has(flag);
 /**
  * All non-strictly-boolean arguments to node--those with values--must specify those values using `=`, e.g., `--inspect=0.0.0.0`.
  * Unparse these arguments using `yargs-unparser` (which would result in `--inspect 0.0.0.0`), then supply `=` where we have values.
- * Apparently --require in Node.js v8 does NOT want `=`.
  * There's probably an easier or more robust way to do this; fixes welcome
  * @param {Object} opts - Arguments object
  * @returns {string[]} Unparsed arguments using `=` to specify values
@@ -79,9 +78,7 @@ exports.unparseNodeFlags = opts => {
     ? args
         .join(' ')
         .split(/\b/)
-        .map((arg, index, args) =>
-          arg === ' ' && args[index - 1] !== 'require' ? '=' : arg
-        )
+        .map(arg => (arg === ' ' ? '=' : arg))
         .join('')
         .split(' ')
     : [];
diff --git a/lib/cli/run-option-metadata.js b/lib/cli/run-option-metadata.js
index fc870992c9..6bc6604018 100644
--- a/lib/cli/run-option-metadata.js
+++ b/lib/cli/run-option-metadata.js
@@ -18,6 +18,7 @@ const TYPES = (exports.types = {
     'file',
     'global',
     'ignore',
+    'node-option',
     'reporter-option',
     'require',
     'spec',
@@ -79,6 +80,7 @@ exports.aliases = {
   invert: ['i'],
   jobs: ['j'],
   'no-colors': ['C'],
+  'node-option': ['n'],
   parallel: ['p'],
   reporter: ['R'],
   'reporter-option': ['reporter-options', 'O'],
diff --git a/lib/cli/run.js b/lib/cli/run.js
index 79903327c3..06941fab8c 100644
--- a/lib/cli/run.js
+++ b/lib/cli/run.js
@@ -176,6 +176,10 @@ exports.builder = yargs =>
         group: GROUPS.OUTPUT,
         hidden: true
       },
+      'node-option': {
+        description: 'Node or V8 option (no leading "--")',
+        group: GROUPS.CONFIG
+      },
       package: {
         description: 'Path to package.json for config',
         group: GROUPS.CONFIG,
diff --git a/test/integration/options/node-flags.spec.js b/test/integration/options/node-flags.spec.js
index b884482527..b1a87ac296 100644
--- a/test/integration/options/node-flags.spec.js
+++ b/test/integration/options/node-flags.spec.js
@@ -17,3 +17,19 @@ describe('node flags', function() {
     );
   });
 });
+
+describe('node flags using "--node-option"', function() {
+  it('should pass fake option to node and fail with node exception', function(done) {
+    invokeMocha(
+      ['--node-option', 'fake-flag'],
+      function(err, res) {
+        if (err) {
+          return done(err);
+        }
+        expect(res, 'to have failed with output', /bad option: --fake-flag/i);
+        done();
+      },
+      'pipe'
+    );
+  });
+});
diff --git a/test/integration/options/timeout.spec.js b/test/integration/options/timeout.spec.js
index 4470c8b310..e2524c12f8 100644
--- a/test/integration/options/timeout.spec.js
+++ b/test/integration/options/timeout.spec.js
@@ -50,7 +50,7 @@ describe('--timeout', function() {
     });
   });
 
-  it('should disable timeout with --inspect', function(done) {
+  it('should disable timeout with "--inspect"', function(done) {
     var fixture = 'options/slow-test';
     runMochaJSON(fixture, ['--inspect', '--timeout', '200'], function(
       err,
@@ -64,4 +64,19 @@ describe('--timeout', function() {
       done();
     });
   });
+
+  it('should disable timeout with "-n inspect"', function(done) {
+    var fixture = 'options/slow-test';
+    runMochaJSON(fixture, ['-n', 'inspect', '--timeout', '200'], function(
+      err,
+      res
+    ) {
+      if (err) {
+        done(err);
+        return;
+      }
+      expect(res, 'to have passed').and('to have passed test count', 2);
+      done();
+    });
+  });
 });
diff --git a/test/node-unit/cli/node-flags.spec.js b/test/node-unit/cli/node-flags.spec.js
index 838d659fab..627a90378f 100644
--- a/test/node-unit/cli/node-flags.spec.js
+++ b/test/node-unit/cli/node-flags.spec.js
@@ -42,12 +42,7 @@ describe('node-flags', function() {
       it('should return true for flags starting with "preserve-symlinks"', function() {
         expect(isNodeFlag('preserve-symlinks'), 'to be true');
         expect(isNodeFlag('preserve-symlinks-main'), 'to be true');
-        // Node >= v12 both flags exist in process.allowedNodeEnvironmentFlags
-        const nodeVersion = parseInt(process.version.match(/^v(\d+)\./)[1], 10);
-        expect(
-          isNodeFlag('preserve_symlinks'),
-          nodeVersion >= 12 ? 'to be true' : 'to be false'
-        );
+        expect(isNodeFlag('preserve_symlinks'), 'to be true');
       });
 
       it('should return true for flags starting with "harmony-" or "harmony_"', function() {
@@ -69,7 +64,6 @@ describe('node-flags', function() {
       it('should return true for "gc-global"', function() {
         expect(isNodeFlag('gc-global'), 'to be true');
         expect(isNodeFlag('gc_global'), 'to be true');
-        expect(isNodeFlag('gc'), 'to be true');
       });
 
       it('should return true for "es-staging"', function() {