From 01500af07bb4bf55b23f74099b4c9f85c916648b Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 12 Jan 2020 22:38:58 +1300
Subject: [PATCH 01/37] First cut at parse rework

- skip asterisk tests
- other tests runnning
- nested commands untested
- lots of details to check
---
 index.js                           | 348 +++++++++++++----------------
 tests/command.action.test.js       |   8 +-
 tests/command.asterisk.test.js     |   4 +-
 tests/command.exitOverride.test.js |   3 +-
 tests/command.help.test.js         |   6 +-
 tests/command.usage.test.js        |  16 +-
 tests/options.mandatory.test.js    |   5 +-
 7 files changed, 178 insertions(+), 212 deletions(-)

diff --git a/index.js b/index.js
index be0ffbcf8..c2b929fcd 100644
--- a/index.js
+++ b/index.js
@@ -5,8 +5,6 @@
 var EventEmitter = require('events').EventEmitter;
 var spawn = require('child_process').spawn;
 var path = require('path');
-var dirname = path.dirname;
-var basename = path.basename;
 var fs = require('fs');
 
 /**
@@ -132,6 +130,10 @@ function Command(name) {
   this._storeOptionsAsProperties = true; // backwards compatible by default
   this._passCommandToAction = true; // backwards compatible by default
   this._actionResults = [];
+  this._actionHandler = undefined;
+  this._executableHandler = false;
+  this._executableFile = undefined; // custom name for executable
+  this._defaultCommandName = undefined;
 
   this._helpFlags = '-h, --help';
   this._helpDescription = 'output usage information';
@@ -179,9 +181,9 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
 
   if (desc) {
     cmd.description(desc);
-    this.executables = true;
+    cmd._executableHandler = true;
     this._execs.add(cmd._name);
-    if (opts.isDefault) this.defaultExecutable = cmd._name;
+    if (opts.isDefault) this._defaultCommandName = cmd._name;
   }
   cmd._noHelp = !!opts.noHelp;
   cmd._helpFlags = this._helpFlags;
@@ -194,7 +196,7 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
 
   cmd._executableFile = opts.executableFile; // Custom name for executable file
   this.commands.push(cmd);
-  cmd.parseExpectedArgs(args);
+  cmd._parseExpectedArgs(args);
   cmd.parent = this;
 
   if (desc) return this;
@@ -208,7 +210,7 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
  */
 
 Command.prototype.arguments = function(desc) {
-  return this.parseExpectedArgs(desc.split(/ +/));
+  return this._parseExpectedArgs(desc.split(/ +/));
 };
 
 /**
@@ -229,10 +231,10 @@ Command.prototype.addImplicitHelpCommand = function() {
  *
  * @param {Array} args
  * @return {Command} for chaining
- * @api public
+ * @api private
  */
 
-Command.prototype.parseExpectedArgs = function(args) {
+Command.prototype._parseExpectedArgs = function(args) {
   if (!args.length) return;
   var self = this;
   args.forEach(function(arg) {
@@ -323,37 +325,8 @@ Command.prototype._exit = function(exitCode, code, message) {
 
 Command.prototype.action = function(fn) {
   var self = this;
-  var listener = function(args, unknown) {
-    // Parse any so-far unknown options
-    args = args || [];
-    unknown = unknown || [];
-
-    var parsed = self.parseOptions(unknown);
-
-    // Output help if necessary
-    outputHelpIfRequested(self, parsed.unknown);
-    self._checkForMissingMandatoryOptions();
-
-    // If there are still any unknown options, then we simply die.
-    if (parsed.unknown.length > 0) {
-      self.unknownOption(parsed.unknown[0]);
-    }
-
-    args = args.concat(parsed.operands, parsed.unknown);
-
-    self._args.forEach(function(expectedArg, i) {
-      if (expectedArg.required && args[i] == null) {
-        self.missingArgument(expectedArg.name);
-      } else if (expectedArg.variadic) {
-        if (i !== self._args.length - 1) {
-          self.variadicArgNotLast(expectedArg.name);
-        }
-
-        args[i] = args.splice(i);
-      }
-    });
-
-    // The .action callback takes an extra parameter which is the command itself.
+  var listener = function(args) {
+    // The .action callback takes an extra parameter which is the command or options.
     var expectedArgsCount = self._args.length;
     var actionArgs = args.slice(0, expectedArgsCount);
     if (self._passCommandToAction) {
@@ -374,14 +347,7 @@ Command.prototype.action = function(fn) {
     }
     rootCommand._actionResults.push(actionResult);
   };
-  var parent = this.parent || this;
-  if (parent === this) {
-    parent.on('program-command', listener);
-  } else {
-    parent.on('command:' + this._name, listener);
-  }
-
-  if (this._alias) parent.on('command:' + this._alias, listener);
+  this._actionHandler = listener;
   return this;
 };
 
@@ -425,7 +391,7 @@ Command.prototype._optionEx = function(config, flags, description, fn, defaultVa
     // when --no-foo we make sure default is true, unless a --foo option is already defined
     if (option.negate) {
       const positiveLongFlag = option.long.replace(/^--no-/, '--');
-      defaultValue = self.optionFor(positiveLongFlag) ? self._getOptionValue(name) : true;
+      defaultValue = self._findOption(positiveLongFlag) ? self._getOptionValue(name) : true;
     }
     // preassign only if we have a default
     if (defaultValue !== undefined) {
@@ -623,79 +589,32 @@ Command.prototype._getOptionValue = function(key) {
 
 Command.prototype.parse = function(argv) {
   // implicit help
-  if (this.executables) this.addImplicitHelpCommand();
+  // if (this._executables) this.addImplicitHelpCommand(); ????
 
   // store raw args
   this.rawArgs = argv;
 
-  // guess name
-  this._name = this._name || basename(argv[1], '.js');
+  // Guess name, used in usage in help. Not trying very hard. See _executeSubCommand for trying hard by checking files.
+  this._name = this._name || path.basename(argv[1], path.extname(argv[1]));
 
-  // github-style sub-commands with no sub-command
-  if (this.executables && argv.length < 3 && !this.defaultExecutable) {
-    // this user needs help
-    argv.push(this._helpLongFlag);
-  }
-
-  // process argv, leaving off first two args which are app and scriptname.
-  const parsed = this.parseOptions(argv.slice(2));
-  const args = parsed.operands.concat(parsed.unknown);
-  this.args = args.slice();
+  this._parseCommand([], argv.slice(2));
 
-  var result = this.parseArgs(parsed.operands, parsed.unknown);
+  // const args = this.args;
 
-  if (args[0] === 'help' && args.length === 1) this.help();
+  // if (args[0] === 'help' && args.length === 1) this.help();
 
-  // Note for future: we could return early if we found an action handler in parseArgs, as none of following code needed?
+  // // <cmd> --help
+  // if (args[0] === 'help') {
+  //   args[0] = args[1];
+  //   args[1] = this._helpLongFlag;
+  // } else {
+  //   // If calling through to executable subcommand we could check for help flags before failing,
+  //   // but a somewhat unlikely case since program options not passed to executable subcommands.
+  //   // Wait for reports to see if check needed and what usage pattern is.
+  //   this._checkForMissingMandatoryOptions();
+  // }
 
-  // <cmd> --help
-  if (args[0] === 'help') {
-    args[0] = args[1];
-    args[1] = this._helpLongFlag;
-  } else {
-    // If calling through to executable subcommand we could check for help flags before failing,
-    // but a somewhat unlikely case since program options not passed to executable subcommands.
-    // Wait for reports to see if check needed and what usage pattern is.
-    this._checkForMissingMandatoryOptions();
-  }
-
-  // executable sub-commands
-  // (Debugging note for future: args[0] is not right if an action has been called)
-  var name = result.args[0];
-  var subCommand = null;
-
-  // Look for subcommand
-  if (name) {
-    subCommand = this.commands.find(function(command) {
-      return command._name === name;
-    });
-  }
-
-  // Look for alias
-  if (!subCommand && name) {
-    subCommand = this.commands.find(function(command) {
-      return command.alias() === name;
-    });
-    if (subCommand) {
-      name = subCommand._name;
-      args[0] = name;
-    }
-  }
-
-  // Look for default subcommand
-  if (!subCommand && this.defaultExecutable) {
-    name = this.defaultExecutable;
-    args.unshift(name);
-    subCommand = this.commands.find(function(command) {
-      return command._name === name;
-    });
-  }
-
-  if (this._execs.has(name)) {
-    return this.executeSubCommand(argv, args, subCommand ? subCommand._executableFile : undefined);
-  }
-
-  return result;
+  return this;
 };
 
 /**
@@ -707,6 +626,7 @@ Command.prototype.parse = function(argv) {
  * @return {Promise}
  * @api public
  */
+
 Command.prototype.parseAsync = function(argv) {
   this.parse(argv);
   return Promise.all(this._actionResults);
@@ -715,59 +635,55 @@ Command.prototype.parseAsync = function(argv) {
 /**
  * Execute a sub-command executable.
  *
- * @param {Array} argv
- * @param {Array} args
- * @param {Array} unknown
- * @param {String} executableFile
  * @api private
  */
 
-Command.prototype.executeSubCommand = function(argv, args, executableFile) {
-  if (!args.length) this.help();
+Command.prototype._executeSubCommand = function(subcommand, args) {
+  args = args.slice();
+  let launchWithNode = false; // Use node for source targets so do not need to get permissions correct, and on Windows.
+  const sourceExt = ['.js', '.ts', '.mjs'];
+
+  // Want the entry script as the reference for command name and directory for searching for other files.
+  let scriptPath = this.rawArgs[1];
+  if (!fs.existsSync(scriptPath) || fs.statSync(scriptPath).isDirectory()) {
+    // When launched using "node foo" will be missing file extension, or "node ." will be pointing at module instead of file.
+    // Try process.mainModule.filename as a fallback.
+    if (process.mainModule && process.mainModule.filename) {
+      scriptPath = process.mainModule.filename;
+    }
+  }
 
-  var isExplicitJS = false; // Whether to use node to launch "executable"
+  let baseDir;
+  try {
+    const resolvedLink = fs.realpathSync(scriptPath);
+    baseDir = path.dirname(resolvedLink);
+  } catch (e) {
+    baseDir = '.'; // dummy, probably not going to find executable!
+  }
 
-  // executable
-  var pm = argv[1];
   // name of the subcommand, like `pm-install`
-  var bin = basename(pm, path.extname(pm)) + '-' + args[0];
-  if (executableFile != null) {
-    bin = executableFile;
-    // Check for same extensions as we scan for below so get consistent launch behaviour.
-    var executableExt = path.extname(executableFile);
-    isExplicitJS = executableExt === '.js' || executableExt === '.ts' || executableExt === '.mjs';
+  let bin = path.basename(scriptPath, path.extname(scriptPath)) + '-' + subcommand._name;
+  if (subcommand._executableFile) {
+    bin = subcommand._executableFile;
   }
 
-  // In case of globally installed, get the base dir where executable
-  //  subcommand file should be located at
-  var baseDir;
-
-  var resolvedLink = fs.realpathSync(pm);
-
-  baseDir = dirname(resolvedLink);
-
-  // prefer local `./<bin>` to bin in the $PATH
-  var localBin = path.join(baseDir, bin);
-
-  // whether bin file is a js script with explicit `.js` or `.ts` extension
-  if (exists(localBin + '.js')) {
-    bin = localBin + '.js';
-    isExplicitJS = true;
-  } else if (exists(localBin + '.ts')) {
-    bin = localBin + '.ts';
-    isExplicitJS = true;
-  } else if (exists(localBin + '.mjs')) {
-    bin = localBin + '.mjs';
-    isExplicitJS = true;
-  } else if (exists(localBin)) {
+  const localBin = path.join(baseDir, bin);
+  if (fs.existsSync(localBin)) {
+    // prefer local `./<bin>` to bin in the $PATH
     bin = localBin;
+  } else {
+    // Look for source files.
+    sourceExt.forEach((ext) => {
+      if (fs.existsSync(`${localBin}${ext}`)) {
+        bin = `${localBin}${ext}`;
+      }
+    });
   }
+  launchWithNode = sourceExt.includes(path.extname(bin));
 
-  args = args.slice(1);
-
-  var proc;
+  let proc;
   if (process.platform !== 'win32') {
-    if (isExplicitJS) {
+    if (launchWithNode) {
       args.unshift(bin);
       // add executable arguments to spawn
       args = incrementNodeInspectorPort(process.execArgv).concat(args);
@@ -783,7 +699,7 @@ Command.prototype.executeSubCommand = function(argv, args, executableFile) {
     proc = spawn(process.execPath, args, { stdio: 'inherit' });
   }
 
-  var signals = ['SIGUSR1', 'SIGUSR2', 'SIGTERM', 'SIGINT', 'SIGHUP'];
+  const signals = ['SIGUSR1', 'SIGUSR2', 'SIGTERM', 'SIGINT', 'SIGHUP'];
   signals.forEach(function(signal) {
     process.on(signal, function() {
       if (proc.killed === false && proc.exitCode === null) {
@@ -822,41 +738,84 @@ Command.prototype.executeSubCommand = function(argv, args, executableFile) {
 };
 
 /**
- * Parse command `args`.
- *
- * When listener(s) are available those
- * callbacks are invoked, otherwise the "*"
- * event is emitted and those actions are invoked.
+ * @api private
+ */
+Command.prototype._dispatchSubcommand = function(operands, unknown) {
+  let subCommand = this._findCommand(operands[0]);
+  if (subCommand) {
+    operands = operands.slice(1);
+  } else {
+    subCommand = this._findCommand(this._defaultCommandName);
+  }
+  if (!subCommand) {
+    // ????
+    throw new Error('Failed to find subcommand');
+  }
+
+  if (subCommand._executableHandler) {
+    this._executeSubCommand(subCommand, operands.concat(unknown));
+  } else {
+    subCommand._parseCommand(operands, unknown);
+  }
+};
+
+/**
+ * Process arguments in context of this command.
  *
- * @param {Array} args
- * @return {Command} for chaining
  * @api private
  */
 
-Command.prototype.parseArgs = function(operands, unknown) {
-  if (operands.length) {
-    const name = operands[0];
-    if (this.listeners('command:' + name).length) {
-      this.emit('command:' + operands[0], operands.slice(1), unknown);
-    } else {
-      this.emit('program-command', operands, unknown);
-      this.emit('command:*', operands, unknown);
-    }
+Command.prototype._parseCommand = function(operands, unknown) {
+  const parsed = this.parseOptions(unknown);
+  operands = operands.concat(parsed.operands);
+  unknown = parsed.unknown;
+  this.args = operands.concat(unknown);
+
+  if (this._defaultCommandName || (operands && this._findCommand(operands[0]))) {
+    this._dispatchSubcommand(operands, unknown);
   } else {
-    outputHelpIfRequested(this, unknown);
+    if (this.commands.length && this.args.length === 0 && !this._actionHandler && !this._defaultCommandName) {
+      // probaby missing subcommand and no handler, user needs help
+      this._helpAndError();
+    }
 
-    // If there were no args and we have unknown options,
-    // then they are extraneous and we need to error.
-    if (unknown.length > 0 && !this.defaultExecutable) {
-      this.unknownOption(unknown[0]);
+    outputHelpIfRequested(this, parsed.unknown);
+    this._checkForMissingMandatoryOptions();
+    if (parsed.unknown.length > 0) {
+      this.unknownOption(parsed.unknown[0]);
     }
-    // Call the program action handler, unless it has a (missing) required parameter and signature does not match.
-    if (this._args.filter(function(a) { return a.required; }).length === 0) {
-      this.emit('program-command');
+
+    if (this._actionHandler) {
+      const self = this;
+      const args = this.args.slice();
+      this._args.forEach(function(arg, i) {
+        if (arg.required && args[i] == null) {
+          self.missingArgument(arg.name);
+        } else if (arg.variadic) {
+          if (i !== self._args.length - 1) {
+            self.variadicArgNotLast(arg.name);
+          }
+
+          args[i] = args.splice(i);
+        }
+      });
+
+      this._actionHandler(args);
+      // this.emit('command:' + this.name(), operands, unknown); // still needed????
+    } else {
+      this.emit('command:*', operands, unknown);
     }
   }
+};
 
-  return this;
+/**
+ * Find matching command.
+ *
+ * @api private
+ */
+Command.prototype._findCommand = function(name) {
+  if (!name) return undefined;
+  return this.commands.find(cmd => cmd._name === name || cmd._alias === name);
 };
 
 /**
@@ -867,7 +826,7 @@ Command.prototype.parseArgs = function(operands, unknown) {
  * @api private
  */
 
-Command.prototype.optionFor = function(arg) {
+Command.prototype._findOption = function(arg) {
   return this.options.find(option => option.is(arg));
 };
 
@@ -927,7 +886,7 @@ Command.prototype.parseOptions = function(argv) {
     }
 
     if (maybeOption(arg)) {
-      const option = this.optionFor(arg);
+      const option = this._findOption(arg);
       // recognised option, call listener to assign value with possible custom processing
       if (option) {
         if (option.required) {
@@ -950,7 +909,7 @@ Command.prototype.parseOptions = function(argv) {
 
     // Look for combo options following single dash, eat first one if known.
     if (arg.length > 2 && arg[0] === '-' && arg[1] !== '-') {
-      const option = this.optionFor(`-${arg[1]}`);
+      const option = this._findOption(`-${arg[1]}`);
       if (option) {
         if (option.required || option.optional) {
           // option with value following in same argument
@@ -967,7 +926,7 @@ Command.prototype.parseOptions = function(argv) {
     // Look for known long flag with value, like --foo=bar
     if (/^--[^=]+=/.test(arg)) {
       const index = arg.indexOf('=');
-      const option = this.optionFor(arg.slice(0, index));
+      const option = this._findOption(arg.slice(0, index));
       if (option && (option.required || option.optional)) {
         this.emit(`option:${option.name()}`, arg.slice(index + 1));
         continue;
@@ -1447,6 +1406,18 @@ Command.prototype.help = function(cb) {
   this._exit(process.exitCode || 0, 'commander.help', '(outputHelp)');
 };
 
+/**
+ * Output help information and exit. Display for error situations.
+ *
+ * @api private
+ */
+
+Command.prototype._helpAndError = function() {
+  this.outputHelp();
+  // message: do not have all displayed text available so only passing placeholder.
+  this._exit(1, 'commander.help', '(outputHelp)');
+};
+
 /**
  * Camel-case the given `flag`
  *
@@ -1554,17 +1525,6 @@ function humanReadableArgName(arg) {
     : '[' + nameOutput + ']';
 }
 
-// for versions before node v0.8 when there weren't `fs.existsSync`
-function exists(file) {
-  try {
-    if (fs.statSync(file).isFile()) {
-      return true;
-    }
-  } catch (e) {
-    return false;
-  }
-}
-
 /**
  * Scan arguments and increment port number for inspect calls (to avoid conflicts when spawning new command).
  *
diff --git a/tests/command.action.test.js b/tests/command.action.test.js
index 4253e0d4b..447028933 100644
--- a/tests/command.action.test.js
+++ b/tests/command.action.test.js
@@ -46,13 +46,19 @@ test('when .action on program with required argument and argument supplied then
 });
 
 test('when .action on program with required argument and argument not supplied then action not called', () => {
+  // Optional. Use internal knowledge to suppress output to keep test output clean.
+  const consoleErrorSpy = jest.spyOn(console, 'error').mockImplementation(() => { });
   const actionMock = jest.fn();
   const program = new commander.Command();
   program
+    .exitOverride()
     .arguments('<file>')
     .action(actionMock);
-  program.parse(['node', 'test']);
+  expect(() => {
+    program.parse(['node', 'test']);
+  }).toThrow();
   expect(actionMock).not.toHaveBeenCalled();
+  consoleErrorSpy.mockRestore();
 });
 
 // Changes made in #729 to call program action handler
diff --git a/tests/command.asterisk.test.js b/tests/command.asterisk.test.js
index 19d0257f9..c458b7b8c 100644
--- a/tests/command.asterisk.test.js
+++ b/tests/command.asterisk.test.js
@@ -10,7 +10,7 @@ const commander = require('../');
 //
 // Historical: the event 'command:*' used to also be shared by the action handler on the program.
 
-describe(".command('*')", () => {
+describe.skip(".command('*')", () => {
   test('when no arguments then asterisk action not called', () => {
     const mockAction = jest.fn();
     const program = new commander.Command();
@@ -58,7 +58,7 @@ describe(".command('*')", () => {
 });
 
 // Test .on explicitly rather than assuming covered by .command
-describe(".on('command:*')", () => {
+describe.skip(".on('command:*')", () => {
   test('when no arguments then listener not called', () => {
     const mockAction = jest.fn();
     const program = new commander.Command();
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index db5fd148c..2521c673e 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -135,9 +135,8 @@ describe('.exitOverride and error details', () => {
       caughtErr = err;
     }
 
-    // This is effectively treated as a deliberate request for help, rather than an error.
     expect(writeSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 0, 'commander.helpDisplayed', '(outputHelp)');
+    expectCommanderError(caughtErr, 1, 'commander.help', '(outputHelp)');
   });
 
   test('when specify --version then throw CommanderError', () => {
diff --git a/tests/command.help.test.js b/tests/command.help.test.js
index b61fbc016..6112d44e4 100644
--- a/tests/command.help.test.js
+++ b/tests/command.help.test.js
@@ -11,7 +11,7 @@ test('when call helpInformation for program then help format is as expected (usa
   program
     .command('my-command <file>');
   const expectedHelpInformation =
-`Usage: test [options] [command]
+`Usage: hack [options] [command]
 
 Options:
   -h, --help         output usage information
@@ -20,7 +20,7 @@ Commands:
   my-command <file>
 `;
 
-  program.parse(['node', 'test']);
+  program._name = 'hack';
   const helpInformation = program.helpInformation();
   expect(helpInformation).toBe(expectedHelpInformation);
 });
@@ -30,7 +30,7 @@ test('when use .description for command then help incudes description', () => {
   program
     .command('simple-command')
     .description('custom-description');
-  program.parse(['node', 'test']);
+  program._help = 'test';
   const helpInformation = program.helpInformation();
   expect(helpInformation).toMatch(/simple-command +custom-description/);
 });
diff --git a/tests/command.usage.test.js b/tests/command.usage.test.js
index 7c3616813..655e09e96 100644
--- a/tests/command.usage.test.js
+++ b/tests/command.usage.test.js
@@ -3,10 +3,10 @@ const commander = require('../');
 test('when default usage and check program help then starts with default usage', () => {
   const program = new commander.Command();
 
-  program.parse(['node', 'test']);
+  program._name = 'hack';
   const helpInformation = program.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp('^Usage: test \\[options\\]'));
+  expect(helpInformation).toMatch(new RegExp('^Usage: hack \\[options\\]'));
 });
 
 test('when custom usage and check program help then starts with custom usage', () => {
@@ -15,10 +15,10 @@ test('when custom usage and check program help then starts with custom usage', (
   program
     .usage(myUsage);
 
-  program.parse(['node', 'test']);
+  program._name = 'hack';
   const helpInformation = program.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp(`^Usage: test ${myUsage}`));
+  expect(helpInformation).toMatch(new RegExp(`^Usage: hack ${myUsage}`));
 });
 
 test('when default usage and check subcommand help then starts with default usage including program name', () => {
@@ -26,10 +26,10 @@ test('when default usage and check subcommand help then starts with default usag
   const subCommand = program
     .command('info');
 
-  program.parse(['node', 'test']);
+  program._name = 'hack';
   const helpInformation = subCommand.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp('^Usage: test info \\[options\\]'));
+  expect(helpInformation).toMatch(new RegExp('^Usage: hack info \\[options\\]'));
 });
 
 test('when custom usage and check subcommand help then starts with custom usage including program name', () => {
@@ -39,8 +39,8 @@ test('when custom usage and check subcommand help then starts with custom usage
     .command('info')
     .usage(myUsage);
 
-  program.parse(['node', 'test']);
+  program._name = 'hack';
   const helpInformation = subCommand.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp(`^Usage: test info ${myUsage}`));
+  expect(helpInformation).toMatch(new RegExp(`^Usage: hack info ${myUsage}`));
 });
diff --git a/tests/options.mandatory.test.js b/tests/options.mandatory.test.js
index 87b725473..921d7b7c1 100644
--- a/tests/options.mandatory.test.js
+++ b/tests/options.mandatory.test.js
@@ -218,10 +218,11 @@ describe('required command option with mandatory value not specified', () => {
       .exitOverride()
       .command('sub')
       .requiredOption('--subby <type>', 'description')
-      .action((cmd) => {});
+      .action((cmd) => {})
+      .command('sub2');
 
     expect(() => {
-      program.parse(['node', 'test']);
+      program.parse(['node', 'test', 'sub2']);
     }).not.toThrow();
   });
 });

From 22c9ca5da083394e317997d0c4e306112402a77e Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 12 Jan 2020 23:15:12 +1300
Subject: [PATCH 02/37] Add check for requiredOption when calling executable
 subcommand

---
 index.js | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/index.js b/index.js
index c2b929fcd..132d75436 100644
--- a/index.js
+++ b/index.js
@@ -607,11 +607,6 @@ Command.prototype.parse = function(argv) {
   // if (args[0] === 'help') {
   //   args[0] = args[1];
   //   args[1] = this._helpLongFlag;
-  // } else {
-  //   // If calling through to executable subcommand we could check for help flags before failing,
-  //   // but a somewhat unlikely case since program options not passed to executable subcommands.
-  //   // Wait for reports to see if check needed and what usage pattern is.
-  //   this._checkForMissingMandatoryOptions();
   // }
 
   return this;
@@ -643,6 +638,9 @@ Command.prototype._executeSubCommand = function(subcommand, args) {
   let launchWithNode = false; // Use node for source targets so do not need to get permissions correct, and on Windows.
   const sourceExt = ['.js', '.ts', '.mjs'];
 
+  // Not checking for help first. Unlikely to have mandatory and executable, and can't robustly test for help flags in external command.
+  this._checkForMissingMandatoryOptions();
+
   // Want the entry script as the reference for command name and directory for searching for other files.
   let scriptPath = this.rawArgs[1];
   if (!fs.existsSync(scriptPath) || fs.statSync(scriptPath).isDirectory()) {
@@ -832,12 +830,13 @@ Command.prototype._findOption = function(arg) {
 
 /**
  * Display an error message if a mandatory option does not have a value.
+ * Lazy calling after checking for help flags from leaf subcommand.
  *
  * @api private
  */
 
 Command.prototype._checkForMissingMandatoryOptions = function() {
-  // Walk up hierarchy so can call from action handler after checking for displaying help.
+  // Walk up hierarchy so can call in subcommand after checking for displaying help.
   for (var cmd = this; cmd; cmd = cmd.parent) {
     cmd.options.forEach((anOption) => {
       if (anOption.mandatory && (cmd._getOptionValue(anOption.attributeName()) === undefined)) {
@@ -1493,19 +1492,16 @@ function optionalWrap(str, width, indent) {
  * Output help information if help flags specified
  *
  * @param {Command} cmd - command to output help for
- * @param {Array} options - array of options to search for -h or --help
+ * @param {Array} args - array of options to search for help flags
  * @api private
  */
 
-function outputHelpIfRequested(cmd, options) {
-  options = options || [];
-
-  for (var i = 0; i < options.length; i++) {
-    if (options[i] === cmd._helpLongFlag || options[i] === cmd._helpShortFlag) {
-      cmd.outputHelp();
-      // (Do not have all displayed text available so only passing placeholder.)
-      cmd._exit(0, 'commander.helpDisplayed', '(outputHelp)');
-    }
+function outputHelpIfRequested(cmd, args) {
+  const helpOption = args.find(arg => arg === cmd._helpLongFlag || arg === cmd._helpShortFlag);
+  if (helpOption) {
+    cmd.outputHelp();
+    // (Do not have all displayed text available so only passing placeholder.)
+    cmd._exit(0, 'commander.helpDisplayed', '(outputHelp)');
   }
 }
 

From de0f20ace028f4439930877550e6891b7ecf6d27 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Mon, 13 Jan 2020 08:56:09 +1300
Subject: [PATCH 03/37] Set program name using supported approach

---
 tests/command.help.test.js  |  4 ++--
 tests/command.usage.test.js | 16 ++++++++--------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tests/command.help.test.js b/tests/command.help.test.js
index 6112d44e4..5e91eaa5d 100644
--- a/tests/command.help.test.js
+++ b/tests/command.help.test.js
@@ -11,7 +11,7 @@ test('when call helpInformation for program then help format is as expected (usa
   program
     .command('my-command <file>');
   const expectedHelpInformation =
-`Usage: hack [options] [command]
+`Usage: test [options] [command]
 
 Options:
   -h, --help         output usage information
@@ -20,7 +20,7 @@ Commands:
   my-command <file>
 `;
 
-  program._name = 'hack';
+  program.name('test');
   const helpInformation = program.helpInformation();
   expect(helpInformation).toBe(expectedHelpInformation);
 });
diff --git a/tests/command.usage.test.js b/tests/command.usage.test.js
index 655e09e96..6140ec93b 100644
--- a/tests/command.usage.test.js
+++ b/tests/command.usage.test.js
@@ -3,10 +3,10 @@ const commander = require('../');
 test('when default usage and check program help then starts with default usage', () => {
   const program = new commander.Command();
 
-  program._name = 'hack';
+  program.name('test');
   const helpInformation = program.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp('^Usage: hack \\[options\\]'));
+  expect(helpInformation).toMatch(new RegExp('^Usage: test \\[options\\]'));
 });
 
 test('when custom usage and check program help then starts with custom usage', () => {
@@ -15,10 +15,10 @@ test('when custom usage and check program help then starts with custom usage', (
   program
     .usage(myUsage);
 
-  program._name = 'hack';
+  program.name('test');
   const helpInformation = program.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp(`^Usage: hack ${myUsage}`));
+  expect(helpInformation).toMatch(new RegExp(`^Usage: test ${myUsage}`));
 });
 
 test('when default usage and check subcommand help then starts with default usage including program name', () => {
@@ -26,10 +26,10 @@ test('when default usage and check subcommand help then starts with default usag
   const subCommand = program
     .command('info');
 
-  program._name = 'hack';
+  program.name('test');
   const helpInformation = subCommand.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp('^Usage: hack info \\[options\\]'));
+  expect(helpInformation).toMatch(new RegExp('^Usage: test info \\[options\\]'));
 });
 
 test('when custom usage and check subcommand help then starts with custom usage including program name', () => {
@@ -39,8 +39,8 @@ test('when custom usage and check subcommand help then starts with custom usage
     .command('info')
     .usage(myUsage);
 
-  program._name = 'hack';
+  program.name('test');
   const helpInformation = subCommand.helpInformation();
 
-  expect(helpInformation).toMatch(new RegExp(`^Usage: hack info ${myUsage}`));
+  expect(helpInformation).toMatch(new RegExp(`^Usage: test info ${myUsage}`));
 });

From 7dc234920752b88d73eb47214619a84c21ac3785 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Mon, 13 Jan 2020 19:28:36 +1300
Subject: [PATCH 04/37] Add .addCommand, easy after previous work

---
 index.js | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 132d75436..c61e376d8 100644
--- a/index.js
+++ b/index.js
@@ -203,6 +203,18 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
   return cmd;
 };
 
+/**
+  * @api public
+  */
+
+Command.prototype.addCommand = function(cmd) {
+  if (!cmd._name) throw Error('error: addCommand name is not specified for command');
+
+  this.commands.push(cmd);
+  cmd.parent = this;
+  return this;
+};
+
 /**
  * Define argument syntax for the top-level command.
  *
@@ -720,7 +732,7 @@ Command.prototype._executeSubCommand = function(subcommand, args) {
     if (err.code === 'ENOENT') {
       console.error('error: %s(1) does not exist, try --help', bin);
     } else if (err.code === 'EACCES') {
-      console.error('error: %s(1) not executable. try chmod or run with root', bin);
+      console.error('error: %s(1) not executable', bin);
     }
     if (!exitCallback) {
       process.exit(1);

From 5e43088e762afe60015a1db9e2388131313e6556 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Mon, 13 Jan 2020 20:19:34 +1300
Subject: [PATCH 05/37] Add support for default command using action handler

- and remove stale _execs
---
 index.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/index.js b/index.js
index c61e376d8..dd8d01674 100644
--- a/index.js
+++ b/index.js
@@ -122,7 +122,6 @@ exports.CommanderError = CommanderError;
 function Command(name) {
   this.commands = [];
   this.options = [];
-  this._execs = new Set();
   this._allowUnknownOption = false;
   this._args = [];
   this._name = name || '';
@@ -182,9 +181,9 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
   if (desc) {
     cmd.description(desc);
     cmd._executableHandler = true;
-    this._execs.add(cmd._name);
-    if (opts.isDefault) this._defaultCommandName = cmd._name;
   }
+  if (opts.isDefault) this._defaultCommandName = cmd._name;
+
   cmd._noHelp = !!opts.noHelp;
   cmd._helpFlags = this._helpFlags;
   cmd._helpDescription = this._helpDescription;
@@ -755,6 +754,7 @@ Command.prototype._dispatchSubcommand = function(operands, unknown) {
   if (subCommand) {
     operands = operands.slice(1);
   } else {
+    outputHelpIfRequested(this, unknown); // Run the help for default command from parent rather than passing to subcommand
     subCommand = this._findCommand(this._defaultCommandName);
   }
   if (!subCommand) {

From d4f87b2865bf45fb0e7341e2bfc67fee455f8fbd Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 14 Jan 2020 23:06:04 +1300
Subject: [PATCH 06/37] Add implicitHelpCommand and change help flags
 description

---
 Readme.md                  |  4 +--
 Readme_zh-CN.md            |  8 ++---
 index.js                   | 65 +++++++++++++++++++-------------------
 tests/command.help.test.js |  2 +-
 tests/helpwrap.test.js     | 10 +++---
 5 files changed, 45 insertions(+), 44 deletions(-)

diff --git a/Readme.md b/Readme.md
index e685f758e..47fbea7c3 100644
--- a/Readme.md
+++ b/Readme.md
@@ -444,7 +444,7 @@ Options:
   -b, --bbq            Add bbq sauce
   -c, --cheese <type>  Add the specified type of cheese (default: "marble")
   -C, --no-cheese      You do not want any cheese
-  -h, --help           output usage information
+  -h, --help           display help for command
 ```
 
 ### Custom help
@@ -488,7 +488,7 @@ Yields the following help output when `node script-name.js -h` or `node script-n
 Usage: custom-help [options]
 
 Options:
-  -h, --help     output usage information
+  -h, --help     display help for command
   -V, --version  output the version number
   -f, --foo      enable some foo
   -b, --bar      enable some bar
diff --git a/Readme_zh-CN.md b/Readme_zh-CN.md
index ca2c8ace4..5347a567a 100644
--- a/Readme_zh-CN.md
+++ b/Readme_zh-CN.md
@@ -31,7 +31,7 @@
     - [.help(cb)](#helpcb)
   - [自定义事件监听](#%e8%87%aa%e5%ae%9a%e4%b9%89%e4%ba%8b%e4%bb%b6%e7%9b%91%e5%90%ac)
   - [零碎知识](#%e9%9b%b6%e7%a2%8e%e7%9f%a5%e8%af%86)
-    - [避免选项命名冲突](#避免选项命名冲突)
+    - [避免选项命名冲突](#%e9%81%bf%e5%85%8d%e9%80%89%e9%a1%b9%e5%91%bd%e5%90%8d%e5%86%b2%e7%aa%81)
     - [TypeScript](#typescript)
     - [Node 选项例如 --harmony](#node-%e9%80%89%e9%a1%b9%e4%be%8b%e5%a6%82---harmony)
     - [Node 调试](#node-%e8%b0%83%e8%af%95)
@@ -39,7 +39,7 @@
   - [例子](#%e4%be%8b%e5%ad%90)
   - [许可证](#%e8%ae%b8%e5%8f%af%e8%af%81)
   - [支持](#%e6%94%af%e6%8c%81)
-    - [企业使用Commander](#企业使用Commander)
+    - [企业使用Commander](#%e4%bc%81%e4%b8%9a%e4%bd%bf%e7%94%a8commander)
 
 ## 安装
 
@@ -435,7 +435,7 @@ Options:
   -b, --bbq            Add bbq sauce
   -c, --cheese <type>  Add the specified type of cheese (default: "marble")
   -C, --no-cheese      You do not want any cheese
-  -h, --help           output usage information
+  -h, --help           display help for command
 ```
 
 ### 自定义帮助
@@ -474,7 +474,7 @@ console.log('stuff');
 Usage: custom-help [options]
 
 Options:
-  -h, --help     output usage information
+  -h, --help     display help for command
   -V, --version  output the version number
   -f, --foo      enable some foo
   -b, --bar      enable some bar
diff --git a/index.js b/index.js
index dd8d01674..fe6cd2e5f 100644
--- a/index.js
+++ b/index.js
@@ -135,9 +135,10 @@ function Command(name) {
   this._defaultCommandName = undefined;
 
   this._helpFlags = '-h, --help';
-  this._helpDescription = 'output usage information';
+  this._helpDescription = 'display help for command';
   this._helpShortFlag = '-h';
   this._helpLongFlag = '--help';
+  this._implicitHelpCommand = undefined;
 }
 
 /**
@@ -225,14 +226,27 @@ Command.prototype.arguments = function(desc) {
 };
 
 /**
- * Add an implicit `help [cmd]` subcommand
- * which invokes `--help` for the given command.
+ * Override default decision whether to add implicit help command.
  *
+ * @return {Command} for chaining
+ * @api public
+ */
+
+Command.prototype.addImplicitHelpCommand = function(enable) {
+  this._implicitHelpCommand = (enable === undefined) || !!enable;
+  return this;
+};
+
+/**
+ * @return {boolean}
  * @api private
  */
 
-Command.prototype.addImplicitHelpCommand = function() {
-  this.command('help [cmd]', 'display help for [cmd]');
+Command.prototype._hasImplicitHelpCommand = function() {
+  if (this._implicitHelpCommand === undefined) {
+    this._implicitHelpCommand = this.commands.length && !this._actionHandler && !this._findCommand('help');
+  }
+  return this._implicitHelpCommand;
 };
 
 /**
@@ -599,9 +613,6 @@ Command.prototype._getOptionValue = function(key) {
  */
 
 Command.prototype.parse = function(argv) {
-  // implicit help
-  // if (this._executables) this.addImplicitHelpCommand(); ????
-
   // store raw args
   this.rawArgs = argv;
 
@@ -610,16 +621,6 @@ Command.prototype.parse = function(argv) {
 
   this._parseCommand([], argv.slice(2));
 
-  // const args = this.args;
-
-  // if (args[0] === 'help' && args.length === 1) this.help();
-
-  // // <cmd> --help
-  // if (args[0] === 'help') {
-  //   args[0] = args[1];
-  //   args[1] = this._helpLongFlag;
-  // }
-
   return this;
 };
 
@@ -749,18 +750,9 @@ Command.prototype._executeSubCommand = function(subcommand, args) {
 /**
  * @api private
  */
-Command.prototype._dispatchSubcommand = function(operands, unknown) {
-  let subCommand = this._findCommand(operands[0]);
-  if (subCommand) {
-    operands = operands.slice(1);
-  } else {
-    outputHelpIfRequested(this, unknown); // Run the help for default command from parent rather than passing to subcommand
-    subCommand = this._findCommand(this._defaultCommandName);
-  }
-  if (!subCommand) {
-    // ????
-    throw new Error('Failed to find subcommand');
-  }
+Command.prototype._dispatchSubcommand = function(commandName, operands, unknown) {
+  const subCommand = this._findCommand(commandName);
+  if (!subCommand) this._helpAndError();
 
   if (subCommand._executableHandler) {
     this._executeSubCommand(subCommand, operands.concat(unknown));
@@ -781,8 +773,17 @@ Command.prototype._parseCommand = function(operands, unknown) {
   unknown = parsed.unknown;
   this.args = operands.concat(unknown);
 
-  if (this._defaultCommandName || (operands && this._findCommand(operands[0]))) {
-    this._dispatchSubcommand(operands, unknown);
+  if (operands && this._findCommand(operands[0])) {
+    this._dispatchSubcommand(operands[0], operands.slice(1), unknown);
+  } else if (this._hasImplicitHelpCommand() && operands[0] === 'help') {
+    if (operands.length === 1) {
+      this.help();
+    } else {
+      this._dispatchSubcommand(operands[1], [], [this._helpLongFlag]);
+    }
+  } else if (this._defaultCommandName) {
+    outputHelpIfRequested(this, unknown); // Run the help for default command from parent rather than passing to default command
+    this._dispatchSubcommand(this._defaultCommandName, operands, unknown);
   } else {
     if (this.commands.length && this.args.length === 0 && !this._actionHandler && !this._defaultCommandName) {
       // probaby missing subcommand and no handler, user needs help
diff --git a/tests/command.help.test.js b/tests/command.help.test.js
index 5e91eaa5d..51e9ed5a7 100644
--- a/tests/command.help.test.js
+++ b/tests/command.help.test.js
@@ -14,7 +14,7 @@ test('when call helpInformation for program then help format is as expected (usa
 `Usage: test [options] [command]
 
 Options:
-  -h, --help         output usage information
+  -h, --help         display help for command
 
 Commands:
   my-command <file>
diff --git a/tests/helpwrap.test.js b/tests/helpwrap.test.js
index 1cfbd55df..61207c990 100644
--- a/tests/helpwrap.test.js
+++ b/tests/helpwrap.test.js
@@ -16,7 +16,7 @@ Options:
   -x -extra-long-option-switch  kjsahdkajshkahd kajhsd akhds kashd kajhs dkha
                                 dkh aksd ka dkha kdh kasd ka kahs dkh sdkh
                                 askdh aksd kashdk ahsd kahs dkha skdh
-  -h, --help                    output usage information
+  -h, --help                    display help for command
 `;
 
   expect(program.helpInformation()).toBe(expectedOutput);
@@ -36,7 +36,7 @@ test('when long option description and default then wrap and indent', () => {
 Options:
   -x -extra-long-option <value>  kjsahdkajshkahd kajhsd akhds (default: "aaa
                                  bbb ccc ddd eee fff ggg")
-  -h, --help                     output usage information
+  -h, --help                     display help for command
 `;
 
   expect(program.helpInformation()).toBe(expectedOutput);
@@ -56,7 +56,7 @@ test('when long command description then wrap and indent', () => {
 
 Options:
   -x -extra-long-option-switch  x
-  -h, --help                    output usage information
+  -h, --help                    display help for command
 
 Commands:
   alpha                         Lorem mollit quis dolor ex do eu quis ad insa
@@ -80,7 +80,7 @@ test('when not enough room then help not wrapped', () => {
 `Usage:  [options] [command]
 
 Options:
-  -h, --help            output usage information
+  -h, --help            display help for command
 
 Commands:
   1234567801234567890x  ${commandDescription}
@@ -112,7 +112,7 @@ Options:
   Time can also be specified using special values:
     "dawn" - From night to sunrise.
   
-  -h, --help          output usage information
+  -h, --help          display help for command
 `;
 
   expect(program.helpInformation()).toBe(expectedOutput);

From f51b0e323db2f023758b63fb04f8de8c6c0ddfc6 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 14 Jan 2020 23:35:36 +1300
Subject: [PATCH 07/37] Add implicit help command to help

---
 index.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index fe6cd2e5f..a400540a4 100644
--- a/index.js
+++ b/index.js
@@ -1165,7 +1165,7 @@ Command.prototype.name = function(str) {
  */
 
 Command.prototype.prepareCommands = function() {
-  return this.commands.filter(function(cmd) {
+  const commandDetails = this.commands.filter(function(cmd) {
     return !cmd._noHelp;
   }).map(function(cmd) {
     var args = cmd._args.map(function(arg) {
@@ -1180,6 +1180,11 @@ Command.prototype.prepareCommands = function() {
       cmd._description
     ];
   });
+
+  if (this._hasImplicitHelpCommand()) {
+    commandDetails.push(['help [command]', 'display help for command']);
+  }
+  return commandDetails;
 };
 
 /**

From e42152451a74277e0eba6fa7332f2578db07fa82 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 14 Jan 2020 23:45:48 +1300
Subject: [PATCH 08/37] Turn off implicit help command for most help tests

---
 tests/command.commandHelp.test.js | 2 ++
 tests/command.help.test.js        | 1 +
 tests/helpwrap.test.js            | 2 ++
 3 files changed, 5 insertions(+)

diff --git a/tests/command.commandHelp.test.js b/tests/command.commandHelp.test.js
index 57428ce53..538adedea 100644
--- a/tests/command.commandHelp.test.js
+++ b/tests/command.commandHelp.test.js
@@ -5,6 +5,7 @@ const commander = require('../');
 test('when program has command then appears in commandHelp', () => {
   const program = new commander.Command();
   program
+    .addImplicitHelpCommand(false)
     .command('bare');
   const commandHelp = program.commandHelp();
   expect(commandHelp).toBe('Commands:\n  bare\n');
@@ -13,6 +14,7 @@ test('when program has command then appears in commandHelp', () => {
 test('when program has command with optional arg then appears in commandHelp', () => {
   const program = new commander.Command();
   program
+    .addImplicitHelpCommand(false)
     .command('bare [bare-arg]');
   const commandHelp = program.commandHelp();
   expect(commandHelp).toEqual('Commands:\n  bare [bare-arg]\n');
diff --git a/tests/command.help.test.js b/tests/command.help.test.js
index 51e9ed5a7..5ed1daa42 100644
--- a/tests/command.help.test.js
+++ b/tests/command.help.test.js
@@ -18,6 +18,7 @@ Options:
 
 Commands:
   my-command <file>
+  help [command]     display help for command
 `;
 
   program.name('test');
diff --git a/tests/helpwrap.test.js b/tests/helpwrap.test.js
index 61207c990..0baa114bb 100644
--- a/tests/helpwrap.test.js
+++ b/tests/helpwrap.test.js
@@ -49,6 +49,7 @@ test('when long command description then wrap and indent', () => {
   const program = new commander.Command();
   program
     .option('-x -extra-long-option-switch', 'x')
+    .addImplicitHelpCommand(false)
     .command('alpha', 'Lorem mollit quis dolor ex do eu quis ad insa a commodo esse.');
 
   const expectedOutput =
@@ -74,6 +75,7 @@ test('when not enough room then help not wrapped', () => {
   const program = new commander.Command();
   const commandDescription = 'description text of very long command which should not be automatically be wrapped. Do fugiat eiusmod ipsum laboris excepteur pariatur sint ullamco tempor labore eu.';
   program
+    .addImplicitHelpCommand(false)
     .command('1234567801234567890x', commandDescription);
 
   const expectedOutput =

From a257e49c3a576605477d4103f343a1ab2c050552 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Fri, 17 Jan 2020 00:24:28 +1300
Subject: [PATCH 09/37] .addHelpCommand

---
 index.js                          | 39 +++++++++++++++++++++++--------
 tests/command.commandHelp.test.js |  4 ++--
 tests/helpwrap.test.js            |  4 ++--
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/index.js b/index.js
index a400540a4..dcc0167e3 100644
--- a/index.js
+++ b/index.js
@@ -138,7 +138,10 @@ function Command(name) {
   this._helpDescription = 'display help for command';
   this._helpShortFlag = '-h';
   this._helpLongFlag = '--help';
-  this._implicitHelpCommand = undefined;
+  this._hasImplicitHelpCommand = undefined;
+  this._helpCommandName = 'help';
+  this._helpCommandnameAndArgs = 'help [command]';
+  this._helpCommandDescription = 'display help for command';
 }
 
 /**
@@ -190,6 +193,9 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
   cmd._helpDescription = this._helpDescription;
   cmd._helpShortFlag = this._helpShortFlag;
   cmd._helpLongFlag = this._helpLongFlag;
+  cmd._helpCommandName = this._helpCommandName;
+  cmd._helpCommandnameAndArgs = this._helpCommandnameAndArgs;
+  cmd._helpCommandDescription = this._helpCommandDescription;
   cmd._exitCallback = this._exitCallback;
   cmd._storeOptionsAsProperties = this._storeOptionsAsProperties;
   cmd._passCommandToAction = this._passCommandToAction;
@@ -228,12 +234,25 @@ Command.prototype.arguments = function(desc) {
 /**
  * Override default decision whether to add implicit help command.
  *
+ *    addHelpCommand() // force on
+ *    addHelpCommand(false); // force off
+ *    addHelpCommand('help [cmd]', 'display help for [cmd]'); // force on with custom detais
+ *
  * @return {Command} for chaining
  * @api public
  */
 
-Command.prototype.addImplicitHelpCommand = function(enable) {
-  this._implicitHelpCommand = (enable === undefined) || !!enable;
+Command.prototype.addHelpCommand = function(enableOrNameAndArgs, description) {
+  if (enableOrNameAndArgs === false) {
+    this._hasImplicitHelpCommand = false;
+  } else {
+    this._hasImplicitHelpCommand = true;
+    if (typeof enableOrNameAndArgs === 'string') {
+      this._helpCommandName = enableOrNameAndArgs.split(' ')[0];
+      this._helpCommandnameAndArgs = enableOrNameAndArgs;
+    }
+    this._helpCommandDescription = description || this._helpCommandDescription;
+  }
   return this;
 };
 
@@ -242,11 +261,11 @@ Command.prototype.addImplicitHelpCommand = function(enable) {
  * @api private
  */
 
-Command.prototype._hasImplicitHelpCommand = function() {
-  if (this._implicitHelpCommand === undefined) {
-    this._implicitHelpCommand = this.commands.length && !this._actionHandler && !this._findCommand('help');
+Command.prototype._lazyHasImplicitHelpCommand = function() {
+  if (this._hasImplicitHelpCommand === undefined) {
+    this._hasImplicitHelpCommand = this.commands.length && !this._actionHandler && !this._findCommand('help');
   }
-  return this._implicitHelpCommand;
+  return this._hasImplicitHelpCommand;
 };
 
 /**
@@ -775,7 +794,7 @@ Command.prototype._parseCommand = function(operands, unknown) {
 
   if (operands && this._findCommand(operands[0])) {
     this._dispatchSubcommand(operands[0], operands.slice(1), unknown);
-  } else if (this._hasImplicitHelpCommand() && operands[0] === 'help') {
+  } else if (this._lazyHasImplicitHelpCommand() && operands[0] === this._helpCommandName) {
     if (operands.length === 1) {
       this.help();
     } else {
@@ -1181,8 +1200,8 @@ Command.prototype.prepareCommands = function() {
     ];
   });
 
-  if (this._hasImplicitHelpCommand()) {
-    commandDetails.push(['help [command]', 'display help for command']);
+  if (this._lazyHasImplicitHelpCommand()) {
+    commandDetails.push([this._helpCommandnameAndArgs, this._helpCommandDescription]);
   }
   return commandDetails;
 };
diff --git a/tests/command.commandHelp.test.js b/tests/command.commandHelp.test.js
index 538adedea..37b3e24c3 100644
--- a/tests/command.commandHelp.test.js
+++ b/tests/command.commandHelp.test.js
@@ -5,7 +5,7 @@ const commander = require('../');
 test('when program has command then appears in commandHelp', () => {
   const program = new commander.Command();
   program
-    .addImplicitHelpCommand(false)
+    .addHelpCommand(false)
     .command('bare');
   const commandHelp = program.commandHelp();
   expect(commandHelp).toBe('Commands:\n  bare\n');
@@ -14,7 +14,7 @@ test('when program has command then appears in commandHelp', () => {
 test('when program has command with optional arg then appears in commandHelp', () => {
   const program = new commander.Command();
   program
-    .addImplicitHelpCommand(false)
+    .addHelpCommand(false)
     .command('bare [bare-arg]');
   const commandHelp = program.commandHelp();
   expect(commandHelp).toEqual('Commands:\n  bare [bare-arg]\n');
diff --git a/tests/helpwrap.test.js b/tests/helpwrap.test.js
index 0baa114bb..444aa480a 100644
--- a/tests/helpwrap.test.js
+++ b/tests/helpwrap.test.js
@@ -49,7 +49,7 @@ test('when long command description then wrap and indent', () => {
   const program = new commander.Command();
   program
     .option('-x -extra-long-option-switch', 'x')
-    .addImplicitHelpCommand(false)
+    .addHelpCommand(false)
     .command('alpha', 'Lorem mollit quis dolor ex do eu quis ad insa a commodo esse.');
 
   const expectedOutput =
@@ -75,7 +75,7 @@ test('when not enough room then help not wrapped', () => {
   const program = new commander.Command();
   const commandDescription = 'description text of very long command which should not be automatically be wrapped. Do fugiat eiusmod ipsum laboris excepteur pariatur sint ullamco tempor labore eu.';
   program
-    .addImplicitHelpCommand(false)
+    .addHelpCommand(false)
     .command('1234567801234567890x', commandDescription);
 
   const expectedOutput =

From 6b7a7c6e6ee047af699000fa7c961ba071d46eaf Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 18 Jan 2020 22:57:34 +1300
Subject: [PATCH 10/37] Remove addHelpCommand from tests and make match more
 narrow

---
 tests/command.commandHelp.test.js | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tests/command.commandHelp.test.js b/tests/command.commandHelp.test.js
index 37b3e24c3..4f6198c94 100644
--- a/tests/command.commandHelp.test.js
+++ b/tests/command.commandHelp.test.js
@@ -5,17 +5,15 @@ const commander = require('../');
 test('when program has command then appears in commandHelp', () => {
   const program = new commander.Command();
   program
-    .addHelpCommand(false)
     .command('bare');
   const commandHelp = program.commandHelp();
-  expect(commandHelp).toBe('Commands:\n  bare\n');
+  expect(commandHelp).toMatch(/Commands:\n +bare\n/);
 });
 
 test('when program has command with optional arg then appears in commandHelp', () => {
   const program = new commander.Command();
   program
-    .addHelpCommand(false)
     .command('bare [bare-arg]');
   const commandHelp = program.commandHelp();
-  expect(commandHelp).toEqual('Commands:\n  bare [bare-arg]\n');
+  expect(commandHelp).toMatch(/Commands:\n +bare \[bare-arg\]\n/);
 });

From b5b062c686f52aaab89b58d0635e5de51da5b3ec Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 18 Jan 2020 22:57:53 +1300
Subject: [PATCH 11/37] Use test of complete default help output

---
 tests/helpwrap.test.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/helpwrap.test.js b/tests/helpwrap.test.js
index 444aa480a..22f296693 100644
--- a/tests/helpwrap.test.js
+++ b/tests/helpwrap.test.js
@@ -1,6 +1,7 @@
 const commander = require('../');
 
 // Test auto wrap and indent with some manual strings.
+// Fragile tests with complete help output.
 
 test('when long option description then wrap and indent', () => {
   const oldColumns = process.stdout.columns;
@@ -49,7 +50,6 @@ test('when long command description then wrap and indent', () => {
   const program = new commander.Command();
   program
     .option('-x -extra-long-option-switch', 'x')
-    .addHelpCommand(false)
     .command('alpha', 'Lorem mollit quis dolor ex do eu quis ad insa a commodo esse.');
 
   const expectedOutput =
@@ -62,6 +62,7 @@ Options:
 Commands:
   alpha                         Lorem mollit quis dolor ex do eu quis ad insa
                                 a commodo esse.
+  help [command]                display help for command
 `;
 
   expect(program.helpInformation()).toBe(expectedOutput);
@@ -75,7 +76,6 @@ test('when not enough room then help not wrapped', () => {
   const program = new commander.Command();
   const commandDescription = 'description text of very long command which should not be automatically be wrapped. Do fugiat eiusmod ipsum laboris excepteur pariatur sint ullamco tempor labore eu.';
   program
-    .addHelpCommand(false)
     .command('1234567801234567890x', commandDescription);
 
   const expectedOutput =
@@ -86,6 +86,7 @@ Options:
 
 Commands:
   1234567801234567890x  ${commandDescription}
+  help [command]        display help for command
 `;
 
   expect(program.helpInformation()).toBe(expectedOutput);

From 3be5ba3a0d0d565651b5b3cbd89b3f47d10bd423 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 18 Jan 2020 23:30:33 +1300
Subject: [PATCH 12/37] Add tests for whether implicit help appears in help

---
 index.js                          |  2 +-
 tests/command.helpCommand.test.js | 38 +++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 tests/command.helpCommand.test.js

diff --git a/index.js b/index.js
index dcc0167e3..35f74b15d 100644
--- a/index.js
+++ b/index.js
@@ -1305,7 +1305,7 @@ Command.prototype.optionHelp = function() {
  */
 
 Command.prototype.commandHelp = function() {
-  if (!this.commands.length) return '';
+  if (!this.commands.length && !this._lazyHasImplicitHelpCommand()) return '';
 
   var commands = this.prepareCommands();
   var width = this.padWidth();
diff --git a/tests/command.helpCommand.test.js b/tests/command.helpCommand.test.js
new file mode 100644
index 000000000..da9499379
--- /dev/null
+++ b/tests/command.helpCommand.test.js
@@ -0,0 +1,38 @@
+const commander = require('../');
+
+describe('help command in displayed help', () => {
+  test('when program has no subcommands then no automatic help command', () => {
+    const program = new commander.Command();
+    const helpInformation = program.helpInformation();
+    expect(helpInformation).not.toMatch(/help \[command\]/);
+  });
+
+  test('when program has no subcommands and add help command then has help command', () => {
+    const program = new commander.Command();
+    program.addHelpCommand(true);
+    const helpInformation = program.helpInformation();
+    expect(helpInformation).toMatch(/help \[command\]/);
+  });
+
+  test('when program has subcommands then has automatic help command', () => {
+    const program = new commander.Command();
+    program.command('foo');
+    const helpInformation = program.helpInformation();
+    expect(helpInformation).toMatch(/help \[command\]/);
+  });
+
+  test('when program has subcommands and suppress help command then no help command', () => {
+    const program = new commander.Command();
+    program.addHelpCommand(false);
+    program.command('foo');
+    const helpInformation = program.helpInformation();
+    expect(helpInformation).not.toMatch(/help \[command\]/);
+  });
+
+  test('when add custom help command then custom help command', () => {
+    const program = new commander.Command();
+    program.addHelpCommand('help command', 'help description');
+    const helpInformation = program.helpInformation();
+    expect(helpInformation).toMatch(/help command +help description/);
+  });
+});

From b4c055b9b36839b8dfb069b4d3f8dae14cef780c Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 08:24:07 +1300
Subject: [PATCH 13/37] Add tests that help command dispatched to correct
 command

---
 tests/command.helpCommand.test.js | 64 ++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/tests/command.helpCommand.test.js b/tests/command.helpCommand.test.js
index da9499379..be2d5a5b3 100644
--- a/tests/command.helpCommand.test.js
+++ b/tests/command.helpCommand.test.js
@@ -1,6 +1,6 @@
 const commander = require('../');
 
-describe('help command in displayed help', () => {
+describe('help command listed in helpInformation', () => {
   test('when program has no subcommands then no automatic help command', () => {
     const program = new commander.Command();
     const helpInformation = program.helpInformation();
@@ -36,3 +36,65 @@ describe('help command in displayed help', () => {
     expect(helpInformation).toMatch(/help command +help description/);
   });
 });
+
+describe('help command processed on correct command', () => {
+  // Use internal knowledge to suppress output to keep test output clean.
+  let consoleErrorSpy;
+  let writeSpy;
+
+  beforeAll(() => {
+    consoleErrorSpy = jest.spyOn(console, 'error').mockImplementation(() => { });
+    writeSpy = jest.spyOn(process.stdout, 'write').mockImplementation(() => { });
+  });
+
+  afterEach(() => {
+    consoleErrorSpy.mockClear();
+    writeSpy.mockClear();
+  });
+
+  afterAll(() => {
+    consoleErrorSpy.mockRestore();
+    writeSpy.mockRestore();
+  });
+
+  test('when "program help" then program', () => {
+    const program = new commander.Command();
+    program.exitOverride();
+    program.command('sub1');
+    program.exitOverride(() => { throw new Error('program'); });
+    expect(() => {
+      program.parse('node test.js help'.split(' '));
+    }).toThrow('program');
+  });
+
+  test('when "program help sub1" then sub1', () => {
+    const program = new commander.Command();
+    program.exitOverride();
+    const sub1 = program.command('sub1');
+    sub1.exitOverride(() => { throw new Error('sub1'); });
+    expect(() => {
+      program.parse('node test.js help sub1'.split(' '));
+    }).toThrow('sub1');
+  });
+
+  test('when "program sub1 help sub2" then sub2', () => {
+    const program = new commander.Command();
+    program.exitOverride();
+    const sub1 = program.command('sub1');
+    const sub2 = sub1.command('sub2');
+    sub2.exitOverride(() => { throw new Error('sub2'); });
+    expect(() => {
+      program.parse('node test.js sub1 help sub2'.split(' '));
+    }).toThrow('sub2');
+  });
+
+  test('when default command and "program help" then program', () => {
+    const program = new commander.Command();
+    program.exitOverride();
+    program.command('sub1', { isDefault: true });
+    program.exitOverride(() => { throw new Error('program'); });
+    expect(() => {
+      program.parse('node test.js help'.split(' '));
+    }).toThrow('program');
+  });
+});

From c4557328f28b9bdbedbe4c8a7f07d4b1983e375a Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 08:30:39 +1300
Subject: [PATCH 14/37] Add simple nested subcommand test

---
 tests/command.nested.test.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 tests/command.nested.test.js

diff --git a/tests/command.nested.test.js b/tests/command.nested.test.js
new file mode 100644
index 000000000..9445061b2
--- /dev/null
+++ b/tests/command.nested.test.js
@@ -0,0 +1,12 @@
+const commander = require('../');
+
+test('when call nested subcommand then runs', () => {
+  const program = new commander.Command();
+  const leafAction = jest.fn();
+  program
+    .command('sub1')
+    .command('sub2')
+    .action(leafAction);
+  program.parse('node test.js sub1 sub2'.split(' '));
+  expect(leafAction).toHaveBeenCalled();
+});

From bb9fe74fbee7bf8c5ee520157ee8de87c30245d5 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 09:10:06 +1300
Subject: [PATCH 15/37] Add default command tests for action based subcommand

---
 tests/command.default.test.js                 | 61 +++++++++++++++++++
 ...mmand.executableSubcommand.default.test.js | 27 --------
 2 files changed, 61 insertions(+), 27 deletions(-)
 create mode 100644 tests/command.default.test.js
 delete mode 100644 tests/command.executableSubcommand.default.test.js

diff --git a/tests/command.default.test.js b/tests/command.default.test.js
new file mode 100644
index 000000000..ce54783cd
--- /dev/null
+++ b/tests/command.default.test.js
@@ -0,0 +1,61 @@
+const childProcess = require('child_process');
+const path = require('path');
+const commander = require('../');
+
+describe('default executable command', () => {
+  // Calling node explicitly so pm works without file suffix cross-platform.
+  const pm = path.join(__dirname, './fixtures/pm');
+
+  test('when default subcommand and no command then call default', (done) => {
+    childProcess.exec(`node ${pm}`, function(_error, stdout, stderr) {
+      expect(stdout).toBe('default\n');
+      done();
+    });
+  });
+
+  test('when default subcommand and unrecognised argument then call default with argument', (done) => {
+    childProcess.exec(`node ${pm} an-argument`, function(_error, stdout, stderr) {
+      expect(stdout).toBe("default\n[ 'an-argument' ]\n");
+      done();
+    });
+  });
+
+  test('when default subcommand and unrecognised option then call default with option', (done) => {
+    childProcess.exec(`node ${pm} --an-option`, function(_error, stdout, stderr) {
+      expect(stdout).toBe("default\n[ '--an-option' ]\n");
+      done();
+    });
+  });
+});
+
+describe('defaut action command', () => {
+  function makeProgram() {
+    const program = new commander.Command();
+    const actionMock = jest.fn();
+    program
+      .command('other');
+    program
+      .command('default', { isDefault: true })
+      .allowUnknownOption()
+      .action(actionMock);
+    return { program, actionMock };
+  }
+
+  test('when default subcommand and no command then call default', () => {
+    const { program, actionMock } = makeProgram();
+    program.parse('node test.js'.split(' '));
+    expect(actionMock).toHaveBeenCalled();
+  });
+
+  test('when default subcommand and unrecognised argument then call default with argument', () => {
+    const { program, actionMock } = makeProgram();
+    program.parse('node test.js an-argument'.split(' '));
+    expect(actionMock).toHaveBeenCalled();
+  });
+
+  test('when default subcommand and unrecognised option then call default with option', () => {
+    const { program, actionMock } = makeProgram();
+    program.parse('node test.js --an-option'.split(' '));
+    expect(actionMock).toHaveBeenCalled();
+  });
+});
diff --git a/tests/command.executableSubcommand.default.test.js b/tests/command.executableSubcommand.default.test.js
deleted file mode 100644
index c3cf1fe74..000000000
--- a/tests/command.executableSubcommand.default.test.js
+++ /dev/null
@@ -1,27 +0,0 @@
-const childProcess = require('child_process');
-const path = require('path');
-
-// Calling node explicitly so pm works without file suffix cross-platform.
-
-const pm = path.join(__dirname, './fixtures/pm');
-
-test('when default subcommand and no command then call default', (done) => {
-  childProcess.exec(`node ${pm}`, function(_error, stdout, stderr) {
-    expect(stdout).toBe('default\n');
-    done();
-  });
-});
-
-test('when default subcommand and unrecognised argument then call default with argument', (done) => {
-  childProcess.exec(`node ${pm} an-argument`, function(_error, stdout, stderr) {
-    expect(stdout).toBe("default\n[ 'an-argument' ]\n");
-    done();
-  });
-});
-
-test('when default subcommand and unrecognised option then call default with option', (done) => {
-  childProcess.exec(`node ${pm} --an-option`, function(_error, stdout, stderr) {
-    expect(stdout).toBe("default\n[ '--an-option' ]\n");
-    done();
-  });
-});

From f5b0798df932ab183c5f1cdf3670099e695d7cde Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 09:14:47 +1300
Subject: [PATCH 16/37] Remove mainModule, out of scope for current PR

---
 index.js | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/index.js b/index.js
index 35f74b15d..a5eb23be5 100644
--- a/index.js
+++ b/index.js
@@ -673,14 +673,7 @@ Command.prototype._executeSubCommand = function(subcommand, args) {
   this._checkForMissingMandatoryOptions();
 
   // Want the entry script as the reference for command name and directory for searching for other files.
-  let scriptPath = this.rawArgs[1];
-  if (!fs.existsSync(scriptPath) || fs.statSync(scriptPath).isDirectory()) {
-    // When launched using "node foo" will be missing file extension, or "node ." will be pointing at module instead of file.
-    // Try process.mainModule.filename as a fallback.
-    if (process.mainModule && process.mainModule.filename) {
-      scriptPath = process.mainModule.filename;
-    }
-  }
+  const scriptPath = this.rawArgs[1];
 
   let baseDir;
   try {

From b28a0889a8a9913afda1d6488c0e1791d0813304 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 10:09:46 +1300
Subject: [PATCH 17/37] Add legacy asterisk handling and tests

---
 index.js                       |  8 ++++++--
 tests/command.asterisk.test.js | 22 +++++++++++++++++++---
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index a5eb23be5..b69477a12 100644
--- a/index.js
+++ b/index.js
@@ -824,8 +824,12 @@ Command.prototype._parseCommand = function(operands, unknown) {
       });
 
       this._actionHandler(args);
-      // this.emit('command:' + this.name(), operands, unknown); // still needed????
-    } else {
+      this.emit('command:' + this.name(), operands, unknown); // retain ????
+    } else if (operands.length) {
+      // legacy behaviours, command and listener
+      if (this._findCommand('*')) {
+        this._dispatchSubcommand('*', operands, unknown);
+      }
       this.emit('command:*', operands, unknown);
     }
   }
diff --git a/tests/command.asterisk.test.js b/tests/command.asterisk.test.js
index c458b7b8c..cb815d835 100644
--- a/tests/command.asterisk.test.js
+++ b/tests/command.asterisk.test.js
@@ -10,14 +10,30 @@ const commander = require('../');
 //
 // Historical: the event 'command:*' used to also be shared by the action handler on the program.
 
-describe.skip(".command('*')", () => {
+describe(".command('*')", () => {
+  // Use internal knowledge to suppress output to keep test output clean.
+  let writeMock;
+
+  beforeAll(() => {
+    writeMock = jest.spyOn(process.stdout, 'write').mockImplementation(() => { });
+  });
+
+  afterAll(() => {
+    writeMock.mockRestore();
+  });
+
   test('when no arguments then asterisk action not called', () => {
     const mockAction = jest.fn();
     const program = new commander.Command();
     program
+      .exitOverride() // to catch help
       .command('*')
       .action(mockAction);
-    program.parse(['node', 'test']);
+    try {
+      program.parse(['node', 'test']);
+    } catch (err) {
+      ;
+    }
     expect(mockAction).not.toHaveBeenCalled();
   });
 
@@ -58,7 +74,7 @@ describe.skip(".command('*')", () => {
 });
 
 // Test .on explicitly rather than assuming covered by .command
-describe.skip(".on('command:*')", () => {
+describe(".on('command:*')", () => {
   test('when no arguments then listener not called', () => {
     const mockAction = jest.fn();
     const program = new commander.Command();

From 81185fea2b2bd3273ecbe275082a4accfdc114dd Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 21:52:54 +1300
Subject: [PATCH 18/37] Add more initialisation so object in known state

---
 index.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/index.js b/index.js
index b69477a12..832bc80a0 100644
--- a/index.js
+++ b/index.js
@@ -133,7 +133,9 @@ function Command(name) {
   this._executableHandler = false;
   this._executableFile = undefined; // custom name for executable
   this._defaultCommandName = undefined;
+  this._exitCallback = undefined;
 
+  this._noHelp = false;
   this._helpFlags = '-h, --help';
   this._helpDescription = 'display help for command';
   this._helpShortFlag = '-h';

From 9d20c11725802aded8bd10e8cfa7e436797c4cc9 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 21:53:10 +1300
Subject: [PATCH 19/37] Tests for addCommand

---
 tests/command.addCommand.test.js | 43 ++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 tests/command.addCommand.test.js

diff --git a/tests/command.addCommand.test.js b/tests/command.addCommand.test.js
new file mode 100644
index 000000000..688818953
--- /dev/null
+++ b/tests/command.addCommand.test.js
@@ -0,0 +1,43 @@
+const commander = require('../');
+
+// simple sanity check subcommand works
+test('when addCommand and specify subcommand then called', () => {
+  const program = new commander.Command();
+  const leafAction = jest.fn();
+  const sub = new commander.Command();
+  sub
+    .name('sub')
+    .action(leafAction);
+  program
+    .addCommand(sub);
+
+  program.parse('node test.js sub'.split(' '));
+  expect(leafAction).toHaveBeenCalled();
+});
+
+test('when commands added using .addCommand and .command then internals similar', () => {
+  const program1 = new commander.Command();
+  program1.command('sub');
+  const program2 = new commander.Command();
+  program2.addCommand(new commander.Command('sub'));
+
+  // This is a bit of a cheat to check using .addCommand() produces similar result to .command(),
+  // since .command() is well tested and understood.
+
+  const cmd1 = program1.commands[0];
+  const cmd2 = program2.commands[0];
+  expect(cmd1.parent).toBe(program1);
+  expect(cmd2.parent).toBe(program2);
+
+  for (const key of Object.keys(cmd1)) {
+    switch (typeof cmd1[key]) {
+      case 'string':
+      case 'boolean':
+      case 'number':
+      case 'undefined':
+        // Compare vaues in a way that will make some sense in test failure message.
+        expect(`${key}:${cmd1[key]}`).toEqual(`${key}:${cmd2[key]}`);
+        break;
+    }
+  }
+});

From 460e3ec90757dbed5a291ec1319ae36101f41b24 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sun, 19 Jan 2020 22:28:42 +1300
Subject: [PATCH 20/37] Add first cut at enhanced default error detection

---
 index.js                        | 12 ++++++++++--
 tests/options.mandatory.test.js |  3 ++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/index.js b/index.js
index 832bc80a0..da13b0557 100644
--- a/index.js
+++ b/index.js
@@ -828,11 +828,19 @@ Command.prototype._parseCommand = function(operands, unknown) {
       this._actionHandler(args);
       this.emit('command:' + this.name(), operands, unknown); // retain ????
     } else if (operands.length) {
-      // legacy behaviours, command and listener
       if (this._findCommand('*')) {
         this._dispatchSubcommand('*', operands, unknown);
+      } else if (this.listenerCount('command:*')) {
+        this.emit('command:*', operands, unknown);
+      } else if (this.commands.length) {
+        console.error(`Unrecognised command '${this.args[0]}'`);
+        this._helpAndError();
       }
-      this.emit('command:*', operands, unknown);
+    } else if (this.commands.length) {
+      // This command has subcommands and nothing hooked up at this level, so display help.
+      this._helpAndError();
+    } else {
+      // fall through for caller to handle after calling .parse()
     }
   }
 };
diff --git a/tests/options.mandatory.test.js b/tests/options.mandatory.test.js
index 921d7b7c1..fb80d8d03 100644
--- a/tests/options.mandatory.test.js
+++ b/tests/options.mandatory.test.js
@@ -218,7 +218,8 @@ describe('required command option with mandatory value not specified', () => {
       .exitOverride()
       .command('sub')
       .requiredOption('--subby <type>', 'description')
-      .action((cmd) => {})
+      .action((cmd) => {});
+    program
       .command('sub2');
 
     expect(() => {

From 2a480a54def9ce709284932a65f5e46c4ceda7f7 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 19:00:32 +1300
Subject: [PATCH 21/37] Add test that addCommand requires name

---
 index.js                         |  2 +-
 tests/command.addCommand.test.js | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index da13b0557..d5e6868b5 100644
--- a/index.js
+++ b/index.js
@@ -216,7 +216,7 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
   */
 
 Command.prototype.addCommand = function(cmd) {
-  if (!cmd._name) throw Error('error: addCommand name is not specified for command');
+  if (!cmd._name) throw new Error('Command passed to .AddCommand must have a name');
 
   this.commands.push(cmd);
   cmd.parent = this;
diff --git a/tests/command.addCommand.test.js b/tests/command.addCommand.test.js
index 688818953..d77e96562 100644
--- a/tests/command.addCommand.test.js
+++ b/tests/command.addCommand.test.js
@@ -35,9 +35,17 @@ test('when commands added using .addCommand and .command then internals similar'
       case 'boolean':
       case 'number':
       case 'undefined':
-        // Compare vaues in a way that will make some sense in test failure message.
+        // Compare vaues in a way that will be readable in test failure message.
         expect(`${key}:${cmd1[key]}`).toEqual(`${key}:${cmd2[key]}`);
         break;
     }
   }
 });
+
+test('when command without name passed to .addCommand then throw', () => {
+  const program = new commander.Command();
+  const cmd = new commander.Command();
+  expect(() => {
+    program.addCommand(cmd);
+  }).toThrow();
+});

From 0736a773627cbb5991eb318beb2ea8c03039f49b Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 21:01:19 +1300
Subject: [PATCH 22/37] Add block on automatic name generation for deeply
 nested executables

---
 tests/command.addCommand.test.js | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/command.addCommand.test.js b/tests/command.addCommand.test.js
index d77e96562..d9773b17e 100644
--- a/tests/command.addCommand.test.js
+++ b/tests/command.addCommand.test.js
@@ -49,3 +49,21 @@ test('when command without name passed to .addCommand then throw', () => {
     program.addCommand(cmd);
   }).toThrow();
 });
+
+test('when executable command without custom executableFile passed to .addCommand then throw', () => {
+  const program = new commander.Command();
+  const cmd = new commander.Command('sub');
+  cmd.command('exec', 'exec description');
+  expect(() => {
+    program.addCommand(cmd);
+  }).toThrow();
+});
+
+test('when executable command with custom executableFile passed to .addCommand then ok', () => {
+  const program = new commander.Command();
+  const cmd = new commander.Command('sub');
+  cmd.command('exec', 'exec description', { executableFile: 'custom' });
+  expect(() => {
+    program.addCommand(cmd);
+  }).not.toThrow();
+});

From ae611945984c6cd74155b276b29811b2fe62871b Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 21:01:19 +1300
Subject: [PATCH 23/37] Add block on automatic name generation for deeply
 nested executables

---
 index.js                         | 12 ++++++++++++
 tests/command.addCommand.test.js | 18 ++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/index.js b/index.js
index d5e6868b5..7ecaabac0 100644
--- a/index.js
+++ b/index.js
@@ -218,6 +218,18 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
 Command.prototype.addCommand = function(cmd) {
   if (!cmd._name) throw new Error('Command passed to .AddCommand must have a name');
 
+  // To keep things simple, block automatic name generation for deeply nested executables.
+  // Fail fast and detect when adding rather than later when parsing.
+  function checkExplicitNames(commandArray) {
+    commandArray.forEach((cmd) => {
+      if (cmd._executableHandler && !cmd._executableFile) {
+        throw new Error(`Must specify executableFile for deeply nested executable: ${cmd.name()}`);
+      }
+      checkExplicitNames(cmd.commands);
+    });
+  }
+  checkExplicitNames(cmd.commands);
+
   this.commands.push(cmd);
   cmd.parent = this;
   return this;
diff --git a/tests/command.addCommand.test.js b/tests/command.addCommand.test.js
index d77e96562..d9773b17e 100644
--- a/tests/command.addCommand.test.js
+++ b/tests/command.addCommand.test.js
@@ -49,3 +49,21 @@ test('when command without name passed to .addCommand then throw', () => {
     program.addCommand(cmd);
   }).toThrow();
 });
+
+test('when executable command without custom executableFile passed to .addCommand then throw', () => {
+  const program = new commander.Command();
+  const cmd = new commander.Command('sub');
+  cmd.command('exec', 'exec description');
+  expect(() => {
+    program.addCommand(cmd);
+  }).toThrow();
+});
+
+test('when executable command with custom executableFile passed to .addCommand then ok', () => {
+  const program = new commander.Command();
+  const cmd = new commander.Command('sub');
+  cmd.command('exec', 'exec description', { executableFile: 'custom' });
+  expect(() => {
+    program.addCommand(cmd);
+  }).not.toThrow();
+});

From d740db26a34fc74add309656f0e9b413677a8b0c Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 22:13:25 +1300
Subject: [PATCH 24/37] Fix describe name for tests

---
 tests/args.variadic.test.js               | 2 +-
 tests/command.allowUnknownOptions.test.js | 2 +-
 tests/command.unknownOption.test.js       | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/args.variadic.test.js b/tests/args.variadic.test.js
index aed5e4365..8be9f7a7c 100644
--- a/tests/args.variadic.test.js
+++ b/tests/args.variadic.test.js
@@ -2,7 +2,7 @@ const commander = require('../');
 
 // Testing variadic arguments. Testing all the action arguments, but could test just variadicArg.
 
-describe('.version', () => {
+describe('variadic argument', () => {
   // Optional. Use internal knowledge to suppress output to keep test output clean.
   let consoleErrorSpy;
 
diff --git a/tests/command.allowUnknownOptions.test.js b/tests/command.allowUnknownOptions.test.js
index f86ae9f75..da09df7a7 100644
--- a/tests/command.allowUnknownOptions.test.js
+++ b/tests/command.allowUnknownOptions.test.js
@@ -2,7 +2,7 @@ const commander = require('../');
 
 // Not testing output, just testing whether an error is detected.
 
-describe('.version', () => {
+describe('allowUnknownOption', () => {
   // Optional. Use internal knowledge to suppress output to keep test output clean.
   let consoleErrorSpy;
 
diff --git a/tests/command.unknownOption.test.js b/tests/command.unknownOption.test.js
index a4f571f68..18dbb6896 100644
--- a/tests/command.unknownOption.test.js
+++ b/tests/command.unknownOption.test.js
@@ -2,7 +2,7 @@ const commander = require('../');
 
 // Checking for detection of unknown options, including regression tests for some past issues.
 
-describe('.version', () => {
+describe('unknownOption', () => {
   // Optional. Use internal knowledge to suppress output to keep test output clean.
   let consoleErrorSpy;
 

From c529bff7cf82d6ded381a197ce2a709788bbe2e7 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 22:14:29 +1300
Subject: [PATCH 25/37] Refine unknownCommand handling and add tests

---
 index.js                             | 16 +++++++--
 tests/command.exitOverride.test.js   | 17 +++++++++
 tests/command.unknownCommand.test.js | 53 ++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+), 2 deletions(-)
 create mode 100644 tests/command.unknownCommand.test.js

diff --git a/index.js b/index.js
index 7ecaabac0..3e4897717 100644
--- a/index.js
+++ b/index.js
@@ -845,8 +845,7 @@ Command.prototype._parseCommand = function(operands, unknown) {
       } else if (this.listenerCount('command:*')) {
         this.emit('command:*', operands, unknown);
       } else if (this.commands.length) {
-        console.error(`Unrecognised command '${this.args[0]}'`);
-        this._helpAndError();
+        this.unknownCommand();
       }
     } else if (this.commands.length) {
       // This command has subcommands and nothing hooked up at this level, so display help.
@@ -1076,6 +1075,19 @@ Command.prototype.unknownOption = function(flag) {
   this._exit(1, 'commander.unknownOption', message);
 };
 
+/**
+ * Unknown command.
+ *
+ * @param {String} flag
+ * @api private
+ */
+
+Command.prototype.unknownCommand = function() {
+  const message = `error: unrecognised command '${this.args[0]}' (use '${this._helpLongFlag}' for a list of commands)`;
+  console.error(message);
+  this._exit(1, 'commander.unknownCommand', message);
+};
+
 /**
  * Variadic argument with `name` is not the last argument as required.
  *
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index 2521c673e..89c237cc3 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -51,6 +51,23 @@ describe('.exitOverride and error details', () => {
     expectCommanderError(caughtErr, 1, 'commander.unknownOption', "error: unknown option '-m'");
   });
 
+  test('when specify unknown command then throw CommanderError', () => {
+    const program = new commander.Command();
+    program
+      .exitOverride()
+      .command('sub');
+
+    let caughtErr;
+    try {
+      program.parse(['node', 'test', 'oops']);
+    } catch (err) {
+      caughtErr = err;
+    }
+
+    expect(consoleErrorSpy).toHaveBeenCalled();
+    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops' (use '--help' for a list of commands)");
+  });
+
   // Same error as above, but with custom handler.
   test('when supply custom handler then throw custom error', () => {
     const customError = new commander.CommanderError(123, 'custom-code', 'custom-message');
diff --git a/tests/command.unknownCommand.test.js b/tests/command.unknownCommand.test.js
new file mode 100644
index 000000000..65e32ee49
--- /dev/null
+++ b/tests/command.unknownCommand.test.js
@@ -0,0 +1,53 @@
+const commander = require('../');
+
+describe('unknownOption', () => {
+  // Optional. Use internal knowledge to suppress output to keep test output clean.
+  let consoleErrorSpy;
+
+  beforeAll(() => {
+    consoleErrorSpy = jest.spyOn(console, 'error').mockImplementation(() => { });
+  });
+
+  afterEach(() => {
+    consoleErrorSpy.mockClear();
+  });
+
+  afterAll(() => {
+    consoleErrorSpy.mockRestore();
+  });
+
+  test('when unknown argument in simple program then no error', () => {
+    const program = new commander.Command();
+    program.parse('node test.js unknown'.split(' '));
+  });
+
+  test('when unknown command but action handler then no error', () => {
+    const program = new commander.Command();
+    program.command('sub');
+    program
+      .action(() => { });
+    program.parse('node test.js unknown'.split(' '));
+  });
+
+  test('when unknown command but listener then no error', () => {
+    const program = new commander.Command();
+    program.command('sub');
+    program
+      .on('command:*', () => { });
+    program.parse('node test.js unknown'.split(' '));
+  });
+
+  test('when unknown command then error', () => {
+    const program = new commander.Command();
+    program
+      .exitOverride()
+      .command('sub');
+    let caughtErr;
+    try {
+      program.parse('node test.js unknown'.split(' '));
+    } catch (err) {
+      caughtErr = err;
+    }
+    expect(caughtErr.code).toBe('commander.unknownCommand');
+  });
+});

From 365de9940aa5a960a0aa28e296dbe2c06b876f28 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 21 Jan 2020 22:58:46 +1300
Subject: [PATCH 26/37] Add suggestion to try help, when appropriate

---
 index.js                                          | 10 +++++-----
 tests/command.executableSubcommand.lookup.test.js |  4 ++--
 tests/command.exitOverride.test.js                |  6 +++---
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/index.js b/index.js
index 3e4897717..4fd4acda6 100644
--- a/index.js
+++ b/index.js
@@ -756,7 +756,7 @@ Command.prototype._executeSubCommand = function(subcommand, args) {
   }
   proc.on('error', function(err) {
     if (err.code === 'ENOENT') {
-      console.error('error: %s(1) does not exist, try --help', bin);
+      console.error('error: %s(1) does not exist', bin);
     } else if (err.code === 'EACCES') {
       console.error('error: %s(1) not executable', bin);
     }
@@ -838,7 +838,7 @@ Command.prototype._parseCommand = function(operands, unknown) {
       });
 
       this._actionHandler(args);
-      this.emit('command:' + this.name(), operands, unknown); // retain ????
+      this.emit('command:' + this.name(), operands, unknown);
     } else if (operands.length) {
       if (this._findCommand('*')) {
         this._dispatchSubcommand('*', operands, unknown);
@@ -1056,7 +1056,7 @@ Command.prototype.optionMissingArgument = function(option, flag) {
  */
 
 Command.prototype.missingMandatoryOptionValue = function(option) {
-  const message = `error: required option '${option.flags}' not specified`;
+  const message = `error: required option '${option.flags}' not specified (try '${this._helpLongFlag}' for more information)`;
   console.error(message);
   this._exit(1, 'commander.missingMandatoryOptionValue', message);
 };
@@ -1070,7 +1070,7 @@ Command.prototype.missingMandatoryOptionValue = function(option) {
 
 Command.prototype.unknownOption = function(flag) {
   if (this._allowUnknownOption) return;
-  const message = `error: unknown option '${flag}'`;
+  const message = `error: unknown option '${flag}' (try '${this._helpLongFlag}' for more information)`;
   console.error(message);
   this._exit(1, 'commander.unknownOption', message);
 };
@@ -1083,7 +1083,7 @@ Command.prototype.unknownOption = function(flag) {
  */
 
 Command.prototype.unknownCommand = function() {
-  const message = `error: unrecognised command '${this.args[0]}' (use '${this._helpLongFlag}' for a list of commands)`;
+  const message = `error: unrecognised command '${this.args[0]}' (try '${this._helpLongFlag}' for more information)`;
   console.error(message);
   this._exit(1, 'commander.unknownCommand', message);
 };
diff --git a/tests/command.executableSubcommand.lookup.test.js b/tests/command.executableSubcommand.lookup.test.js
index 6f28f8f5d..f18bfb694 100644
--- a/tests/command.executableSubcommand.lookup.test.js
+++ b/tests/command.executableSubcommand.lookup.test.js
@@ -12,7 +12,7 @@ test('when subcommand file missing then error', (done) => {
       // Get uncaught thrown error on Windows
       expect(stderr.length).toBeGreaterThan(0);
     } else {
-      expect(stderr).toBe('error: pm-list(1) does not exist, try --help\n');
+      expect(stderr).toBe('error: pm-list(1) does not exist\n');
     }
     done();
   });
@@ -24,7 +24,7 @@ test('when alias subcommand file missing then error', (done) => {
       // Get uncaught thrown error on Windows
       expect(stderr.length).toBeGreaterThan(0);
     } else {
-      expect(stderr).toBe('error: pm-list(1) does not exist, try --help\n');
+      expect(stderr).toBe('error: pm-list(1) does not exist\n');
     }
     done();
   });
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index 89c237cc3..494c7fea3 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -48,7 +48,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownOption', "error: unknown option '-m'");
+    expectCommanderError(caughtErr, 1, 'commander.unknownOption', "error: unknown option '-m' (try '--help' for more information)");
   });
 
   test('when specify unknown command then throw CommanderError', () => {
@@ -65,7 +65,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops' (use '--help' for a list of commands)");
+    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops' (try '--help' for more information)");
   });
 
   // Same error as above, but with custom handler.
@@ -241,6 +241,6 @@ describe('.exitOverride and error details', () => {
       caughtErr = err;
     }
 
-    expectCommanderError(caughtErr, 1, 'commander.missingMandatoryOptionValue', `error: required option '${optionFlags}' not specified`);
+    expectCommanderError(caughtErr, 1, 'commander.missingMandatoryOptionValue', `error: required option '${optionFlags}' not specified (try '--help' for more information)`);
   });
 });

From aa3805df6526344d17b714044328ad940c09def1 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 20:59:46 +1300
Subject: [PATCH 27/37] Fix typo

---
 tests/command.default.test.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/command.default.test.js b/tests/command.default.test.js
index ce54783cd..619f0f97a 100644
--- a/tests/command.default.test.js
+++ b/tests/command.default.test.js
@@ -28,7 +28,7 @@ describe('default executable command', () => {
   });
 });
 
-describe('defaut action command', () => {
+describe('default action command', () => {
   function makeProgram() {
     const program = new commander.Command();
     const actionMock = jest.fn();

From 4043f2b0c991847390b17950d028d9772f212418 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 21:02:49 +1300
Subject: [PATCH 28/37] Move common command configuration options in README,
 and add isDefault example program

---
 examples/defaultCommand.js | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 examples/defaultCommand.js

diff --git a/examples/defaultCommand.js b/examples/defaultCommand.js
new file mode 100644
index 000000000..c8afa771f
--- /dev/null
+++ b/examples/defaultCommand.js
@@ -0,0 +1,36 @@
+// const commander = require('commander'); // (normal include)
+const commander = require('../'); // include commander in git clone of commander repo
+const program = new commander.Command();
+
+// Example program using the command configuration option isDefault to specify the default command.
+//
+// $ node defaultCommand.js build
+// build
+// $ node defaultCommand.js serve -p 8080
+// server on port 8080
+// $ node defaultCommand.js -p 443
+// server on port 443
+
+program
+  .command('build')
+  .description('build web site for deployment')
+  .action(() => {
+    console.log('build');
+  });
+
+program
+  .command('deploy')
+  .description('deploy web site to production')
+  .action(() => {
+    console.log('deploy');
+  });
+
+program
+  .command('serve', { isDefault: true })
+  .description('launch web server')
+  .option('-p,--port <port_number>', 'web port')
+  .action((opts) => {
+    console.log(`server on port ${opts.port}`);
+  });
+
+program.parse(process.argv);

From 24698c9f73a3befdd36773458c9f5d5edd0ae0eb Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 21:05:44 +1300
Subject: [PATCH 29/37] Add isDefault and example to README

---
 Readme.md | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/Readme.md b/Readme.md
index 47fbea7c3..6aa3be1db 100644
--- a/Readme.md
+++ b/Readme.md
@@ -11,7 +11,7 @@ Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
 
 - [Commander.js](#commanderjs)
   - [Installation](#installation)
-  - [Declaring program variable](#declaring-program-variable)
+  - [Declaring _program_ variable](#declaring-program-variable)
   - [Options](#options)
     - [Common option types, boolean and value](#common-option-types-boolean-and-value)
     - [Default option value](#default-option-value)
@@ -33,7 +33,7 @@ Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
   - [Bits and pieces](#bits-and-pieces)
     - [Avoiding option name clashes](#avoiding-option-name-clashes)
     - [TypeScript](#typescript)
-    - [Node options such as --harmony](#node-options-such-as---harmony)
+    - [Node options such as `--harmony`](#node-options-such-as---harmony)
     - [Node debugging](#node-debugging)
     - [Override exit handling](#override-exit-handling)
   - [Examples](#examples)
@@ -317,6 +317,8 @@ program
   .command('stop [service]', 'stop named service, or all if no name supplied');
 ```
 
+Configuration options can be passed with the call to `.command()`. Specifying `true` for `opts.noHelp` will remove the command from the generated help output. Specifying `true` for `opts.isDefault` will run the subcommand if no other subcommand is specified ([example](./examples/defaultCommand.js)).
+
 ### Specify the argument syntax
 
 You use `.arguments` to specify the arguments for the top-level command, and for subcommands they are included in the `.command` call. Angled brackets (e.g. `<required>`) indicate required input. Square brackets (e.g. `[optional]`) indicate optional input.
@@ -397,13 +399,11 @@ async function main() {
 }
 ```
 
-A command's options on the command line are validated when the command is used. Any unknown options will be reported as an error. However, if an action-based command does not define an action, then the options are not validated.
-
-Configuration options can be passed with the call to `.command()`. Specifying `true` for `opts.noHelp` will remove the command from the generated help output.
+A command's options on the command line are validated when the command is used. Any unknown options will be reported as an error.
 
 ### Git-style executable (sub)commands
 
-When `.command()` is invoked with a description argument, this tells commander that you're going to use separate executables for sub-commands, much like `git(1)` and other popular tools.
+When `.command()` is invoked with a description argument, this tells commander that you're going to use separate executables for sub-commands, much like `git` and other popular tools.
 Commander will search the executables in the directory of the entry script (like `./examples/pm`) with the name `program-subcommand`, like `pm-install`, `pm-search`.
 You can specify a custom name with the `executableFile` configuration option.
 
@@ -422,9 +422,6 @@ program
   .parse(process.argv);
 ```
 
-Configuration options can be passed with the call to `.command()`. Specifying `true` for `opts.noHelp` will remove the command from the generated help output. Specifying `true` for `opts.isDefault` will run the subcommand if no other subcommand is specified.
-Specifying a name with `executableFile` will override the default constructed name.
-
 If the program is designed to be installed globally, make sure the executables have proper modes, like `755`.
 
 ## Automated --help

From cef94eb5904cd38ffcefdbd494beb7c05c2c1cab Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 21:34:15 +1300
Subject: [PATCH 30/37] Add nested commands

---
 Readme.md                  |  4 +++-
 examples/nestedCommands.js | 47 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 examples/nestedCommands.js

diff --git a/Readme.md b/Readme.md
index 6aa3be1db..fd001ca4c 100644
--- a/Readme.md
+++ b/Readme.md
@@ -296,7 +296,9 @@ program.version('0.0.1', '-v, --vers', 'output the current version');
 
 ## Commands
 
-You can specify (sub)commands for your top-level command using `.command`. There are two ways these can be implemented: using an action handler attached to the command, or as a separate executable file (described in more detail later). In the first parameter to `.command` you specify the command name and any command arguments. The arguments may be `<required>` or `[optional]`, and the last argument may also be `variadic...`.
+You can specify (sub)commands for your top-level command using `.command`. There are two ways these can be implemented: using an action handler attached to the command, or as a separate executable file (described in more detail later). The subcommands may be nested ([example](./examples/nestedCommands.js)).
+
+In the first parameter to `.command` you specify the command name and any command arguments. The arguments may be `<required>` or `[optional]`, and the last argument may also be `variadic...`.
 
 For example:
 
diff --git a/examples/nestedCommands.js b/examples/nestedCommands.js
new file mode 100644
index 000000000..3251ee5d8
--- /dev/null
+++ b/examples/nestedCommands.js
@@ -0,0 +1,47 @@
+// const commander = require('commander'); // (normal include)
+const commander = require('../'); // include commander in git clone of commander repo
+const program = new commander.Command();
+
+// Commander supports nested subcommands.
+// .command() can add a subcommand with an action handler or an executable.
+// .addCommand() adds a prepared command with an actiomn handler.
+
+// Example output:
+//
+// $ node nestedCommands.js brew tea
+// brew tea
+// $ node nestedCommands.js heat jug
+// heat jug
+
+// Add nested commands using `.command()`.
+const brew = program.command('brew');
+brew
+  .command('tea')
+  .action(() => {
+    console.log('brew tea');
+  });
+brew
+  .command('tea')
+  .action(() => {
+    console.log('brew tea');
+  });
+
+// Add nested commands using `.addCommand().
+// The command could be created separately in another module.
+function makeHeatCommand() {
+  const heat = new commander.Command('heat');
+  heat
+    .command('jug')
+    .action(() => {
+      console.log('heat jug');
+    });
+  heat
+    .command('pot')
+    .action(() => {
+      console.log('heat pot');
+    });
+  return heat;
+}
+program.addCommand(makeHeatCommand());
+
+program.parse(process.argv);

From e5b68f4497c0a3686e99a74bbeacc6fbb91b368d Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 22:19:55 +1300
Subject: [PATCH 31/37] Document .addHelpCommand, and tweaks

---
 Readme.md                  | 44 +++++++++++++++++++++++++++-----------
 Readme_zh-CN.md            |  6 ++----
 examples/custom-help       |  4 +---
 typings/commander-tests.ts |  4 +---
 4 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/Readme.md b/Readme.md
index fd001ca4c..0dca3cf14 100644
--- a/Readme.md
+++ b/Readme.md
@@ -23,11 +23,12 @@ Read this in other languages: English | [简体中文](./Readme_zh-CN.md)
     - [Specify the argument syntax](#specify-the-argument-syntax)
     - [Action handler (sub)commands](#action-handler-subcommands)
     - [Git-style executable (sub)commands](#git-style-executable-subcommands)
-  - [Automated --help](#automated---help)
+  - [Automated help](#automated-help)
     - [Custom help](#custom-help)
     - [.usage and .name](#usage-and-name)
     - [.outputHelp(cb)](#outputhelpcb)
     - [.helpOption(flags, description)](#helpoptionflags-description)
+    - [.addHelpCommand()](#addhelpcommand)
     - [.help(cb)](#helpcb)
   - [Custom event listeners](#custom-event-listeners)
   - [Bits and pieces](#bits-and-pieces)
@@ -269,7 +270,7 @@ program
 program.parse(process.argv);
 ```
 
-```
+```bash
 $ pizza
 error: required option '-c, --cheese <type>' not specified
 ```
@@ -426,9 +427,10 @@ program
 
 If the program is designed to be installed globally, make sure the executables have proper modes, like `755`.
 
-## Automated --help
+## Automated help
 
- The help information is auto-generated based on the information commander already knows about your program, so the following `--help` info is for free:
+ The help information is auto-generated based on the information commander already knows about your program. The default
+ help option is `-h,--help`.
 
 ```bash
 $ ./examples/pizza --help
@@ -446,14 +448,22 @@ Options:
   -h, --help           display help for command
 ```
 
+A `help` command is added by default if your command has subcommands. It can be used alone, or with a subcommand name to show
+further help for the subcommand. These are effectively the same if the `shell` program has implicit help:
+
+```bash
+shell help
+shell --help
+
+shell help spawn
+shell spawn --help
+```
+
 ### Custom help
 
- You can display arbitrary `-h, --help` information
+ You can display extra `-h, --help` information
  by listening for "--help". Commander will automatically
- exit once you are done so that the remainder of your program
- does not execute causing undesired behaviors, for example
- in the following executable "stuff" will not output when
- `--help` is used.
+ exit after displaying the help.
 
 ```js
 #!/usr/bin/env node
@@ -466,9 +476,7 @@ program
   .option('-b, --bar', 'enable some bar')
   .option('-B, --baz', 'enable some baz');
 
-// must be before .parse() since
-// node's emit() is immediate
-
+// must be before .parse()
 program.on('--help', function(){
   console.log('')
   console.log('Examples:');
@@ -487,11 +495,11 @@ Yields the following help output when `node script-name.js -h` or `node script-n
 Usage: custom-help [options]
 
 Options:
-  -h, --help     display help for command
   -V, --version  output the version number
   -f, --foo      enable some foo
   -b, --bar      enable some bar
   -B, --baz      enable some baz
+  -h, --help     display help for command
 
 Examples:
   $ custom-help --help
@@ -549,6 +557,16 @@ program
   .helpOption('-e, --HELP', 'read more information');
 ```
 
+### .addHelpCommand()
+
+You can explicitly turn on or off the implicit help command with `.addHelpCommand()` and `.addHelpCommand(false)`.
+
+You can both turn on and customise the help command by supplying the name and description:
+
+```js
+program.addHelpCommand('assist [command]', 'show assistance');
+```
+
 ### .help(cb)
 
   Output help information and exit immediately.
diff --git a/Readme_zh-CN.md b/Readme_zh-CN.md
index 5347a567a..147bc1c48 100644
--- a/Readme_zh-CN.md
+++ b/Readme_zh-CN.md
@@ -33,7 +33,7 @@
   - [零碎知识](#%e9%9b%b6%e7%a2%8e%e7%9f%a5%e8%af%86)
     - [避免选项命名冲突](#%e9%81%bf%e5%85%8d%e9%80%89%e9%a1%b9%e5%91%bd%e5%90%8d%e5%86%b2%e7%aa%81)
     - [TypeScript](#typescript)
-    - [Node 选项例如 --harmony](#node-%e9%80%89%e9%a1%b9%e4%be%8b%e5%a6%82---harmony)
+    - [Node 选项例如 `--harmony`](#node-%e9%80%89%e9%a1%b9%e4%be%8b%e5%a6%82---harmony)
     - [Node 调试](#node-%e8%b0%83%e8%af%95)
     - [重载退出(exit)处理](#%e9%87%8d%e8%bd%bd%e9%80%80%e5%87%baexit%e5%a4%84%e7%90%86)
   - [例子](#%e4%be%8b%e5%ad%90)
@@ -453,9 +453,7 @@ program
   .option('-b, --bar', 'enable some bar')
   .option('-B, --baz', 'enable some baz');
 
-// must be before .parse() since
-// node's emit() is immediate
-
+// must be before .parse()
 program.on('--help', function(){
   console.log('');
   console.log('Examples:');
diff --git a/examples/custom-help b/examples/custom-help
index b4719ef50..668a48dfe 100755
--- a/examples/custom-help
+++ b/examples/custom-help
@@ -9,9 +9,7 @@ program
   .option('-b, --bar', 'enable some bar')
   .option('-B, --baz', 'enable some baz');
 
-// must be before .parse() since
-// node's emit() is immediate
-
+// must be before .parse()
 program.on('--help', function() {
   console.log('');
   console.log('Examples:');
diff --git a/typings/commander-tests.ts b/typings/commander-tests.ts
index 7661bcf0e..465bbce0e 100644
--- a/typings/commander-tests.ts
+++ b/typings/commander-tests.ts
@@ -73,9 +73,7 @@ program
     .option('-b, --bar', 'enable some bar')
     .option('-B, --baz', 'enable some baz');
 
-// must be before .parse() since
-// node's emit() is immediate
-
+// must be before .parse()
 program.on('--help', () => {
     console.log('  Examples:');
     console.log('');

From b980c2d202d7c129d4bec66b7d662494d00d157a Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 22:45:04 +1300
Subject: [PATCH 32/37] Remove old default command, and rework command:*
 example

---
 Readme.md       | 13 ++++---------
 Readme_zh-CN.md |  6 ------
 examples/deploy |  6 ------
 3 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/Readme.md b/Readme.md
index 0dca3cf14..7f86990e6 100644
--- a/Readme.md
+++ b/Readme.md
@@ -581,9 +581,10 @@ program.on('option:verbose', function () {
   process.env.VERBOSE = this.verbose;
 });
 
-// error on unknown commands
-program.on('command:*', function () {
-  console.error('Invalid command: %s\nSee --help for a list of available commands.', program.args[0]]);
+// custom error on unknown command
+program.on('command:*', function (operands) {
+  console.error(`Invalid command '${operands[0]}'. Did you mean:`);
+  console.error(mySuggestions(operands[0]));
   process.exit(1);
 });
 ```
@@ -703,12 +704,6 @@ program
     console.log('  $ deploy exec async');
   });
 
-program
-  .command('*')
-  .action(function(env){
-    console.log('deploying "%s"', env);
-  });
-
 program.parse(process.argv);
 ```
 
diff --git a/Readme_zh-CN.md b/Readme_zh-CN.md
index 147bc1c48..7aceda565 100644
--- a/Readme_zh-CN.md
+++ b/Readme_zh-CN.md
@@ -668,12 +668,6 @@ program
     console.log('  $ deploy exec async');
   });
 
-program
-  .command('*')
-  .action(function(env){
-    console.log('deploying "%s"', env);
-  });
-
 program.parse(process.argv);
 ```
 
diff --git a/examples/deploy b/examples/deploy
index d0821f86a..1ec4d2d26 100755
--- a/examples/deploy
+++ b/examples/deploy
@@ -34,10 +34,4 @@ program
     console.log();
   });
 
-program
-  .command('*')
-  .action(function(env) {
-    console.log('deploying "%s"', env);
-  });
-
 program.parse(process.argv);

From 30379ae117dc1a896242ab7d48269f60903a6346 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Wed, 22 Jan 2020 23:13:05 +1300
Subject: [PATCH 33/37] Document .addCommand

---
 Readme.md                  | 11 +++++++++--
 index.js                   |  8 ++++++--
 typings/commander-tests.ts |  3 +++
 typings/index.d.ts         | 14 ++++++--------
 4 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/Readme.md b/Readme.md
index 7f86990e6..0a9601108 100644
--- a/Readme.md
+++ b/Readme.md
@@ -297,9 +297,11 @@ program.version('0.0.1', '-v, --vers', 'output the current version');
 
 ## Commands
 
-You can specify (sub)commands for your top-level command using `.command`. There are two ways these can be implemented: using an action handler attached to the command, or as a separate executable file (described in more detail later). The subcommands may be nested ([example](./examples/nestedCommands.js)).
+You can specify (sub)commands for your top-level command using `.command()` or `.addCommand()`. There are two ways these can be implemented: using an action handler attached to the command, or as a separate executable file (described in more detail later). The subcommands may be nested ([example](./examples/nestedCommands.js)).
 
-In the first parameter to `.command` you specify the command name and any command arguments. The arguments may be `<required>` or `[optional]`, and the last argument may also be `variadic...`.
+In the first parameter to `.command()` you specify the command name and any command arguments. The arguments may be `<required>` or `[optional]`, and the last argument may also be `variadic...`.
+
+You can use `.addCommand()` to add an already configured subcommand to the program.
 
 For example:
 
@@ -318,6 +320,11 @@ program
 program
   .command('start <service>', 'start named service')
   .command('stop [service]', 'stop named service, or all if no name supplied');
+
+// Command prepared separately.
+// Returns top-level command for adding more commands.
+program
+  .addCommand(build.makeBuildCommand());
 ```
 
 Configuration options can be passed with the call to `.command()`. Specifying `true` for `opts.noHelp` will remove the command from the generated help output. Specifying `true` for `opts.isDefault` will run the subcommand if no other subcommand is specified ([example](./examples/defaultCommand.js)).
diff --git a/index.js b/index.js
index 4fd4acda6..c87ed7ef7 100644
--- a/index.js
+++ b/index.js
@@ -212,8 +212,12 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
 };
 
 /**
-  * @api public
-  */
+ * Add a prepared subcommand.
+ *
+ * @param {Command} cmd - new subcommand
+ * @return {Command} parent command for chaining
+ * @api public
+ */
 
 Command.prototype.addCommand = function(cmd) {
   if (!cmd._name) throw new Error('Command passed to .AddCommand must have a name');
diff --git a/typings/commander-tests.ts b/typings/commander-tests.ts
index 465bbce0e..a278c6c28 100644
--- a/typings/commander-tests.ts
+++ b/typings/commander-tests.ts
@@ -111,6 +111,9 @@ program
     .command("name1", "description")
     .command("name2", "description", { isDefault:true })
 
+const preparedCommand = new program.Command('prepared');
+program.addCommand(preparedCommand);
+
 program
     .exitOverride();
 
diff --git a/typings/index.d.ts b/typings/index.d.ts
index d700e8954..5ac15b8d6 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -80,20 +80,18 @@ declare namespace commander {
     command(nameAndArgs: string, description: string, opts?: commander.CommandOptions): Command;
 
     /**
-     * Define argument syntax for the top-level command.
-     *
-     * @returns Command for chaining
+     * Add a prepared subcommand.
+     * 
+     * @returns parent command for chaining
      */
-    arguments(desc: string): Command;
+    addCommand(cmd: Command): Command;
 
     /**
-    * Parse expected `args`.
-     *
-     * For example `["[type]"]` becomes `[{ required: false, name: 'type' }]`.
+     * Define argument syntax for the top-level command.
      *
      * @returns Command for chaining
      */
-     parseExpectedArgs(args: string[]): Command;
+    arguments(desc: string): Command;
 
     /**
      * Register callback to use as replacement for calling process.exit.

From 5fbec7e1db0e0dfaa204f1def0a3d9ce66bcef28 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Sat, 25 Jan 2020 12:32:21 +1300
Subject: [PATCH 34/37] Remove comment referring to removed code.

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index c87ed7ef7..2613a11f9 100644
--- a/index.js
+++ b/index.js
@@ -653,7 +653,7 @@ Command.prototype.parse = function(argv) {
   // store raw args
   this.rawArgs = argv;
 
-  // Guess name, used in usage in help. Not trying very hard. See _executeSubCommand for trying hard by checking files.
+  // Guess name, used in usage in help.
   this._name = this._name || path.basename(argv[1], path.extname(argv[1]));
 
   this._parseCommand([], argv.slice(2));

From c0d62d3b39176d0127bbb9ce1dde400865837131 Mon Sep 17 00:00:00 2001
From: John Gee <j.gee@adinstruments.com>
Date: Mon, 27 Jan 2020 18:56:29 +1300
Subject: [PATCH 35/37] Revert the error tip "try --help", not happy with the
 wording

---
 index.js                           | 6 +++---
 tests/command.exitOverride.test.js | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/index.js b/index.js
index 2613a11f9..a1c5c043a 100644
--- a/index.js
+++ b/index.js
@@ -1060,7 +1060,7 @@ Command.prototype.optionMissingArgument = function(option, flag) {
  */
 
 Command.prototype.missingMandatoryOptionValue = function(option) {
-  const message = `error: required option '${option.flags}' not specified (try '${this._helpLongFlag}' for more information)`;
+  const message = `error: required option '${option.flags}' not specified`;
   console.error(message);
   this._exit(1, 'commander.missingMandatoryOptionValue', message);
 };
@@ -1074,7 +1074,7 @@ Command.prototype.missingMandatoryOptionValue = function(option) {
 
 Command.prototype.unknownOption = function(flag) {
   if (this._allowUnknownOption) return;
-  const message = `error: unknown option '${flag}' (try '${this._helpLongFlag}' for more information)`;
+  const message = `error: unknown option '${flag}'`;
   console.error(message);
   this._exit(1, 'commander.unknownOption', message);
 };
@@ -1087,7 +1087,7 @@ Command.prototype.unknownOption = function(flag) {
  */
 
 Command.prototype.unknownCommand = function() {
-  const message = `error: unrecognised command '${this.args[0]}' (try '${this._helpLongFlag}' for more information)`;
+  const message = `error: unrecognised command '${this.args[0]}'`;
   console.error(message);
   this._exit(1, 'commander.unknownCommand', message);
 };
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index 494c7fea3..31cc0c015 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -48,7 +48,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownOption', "error: unknown option '-m' (try '--help' for more information)");
+    expectCommanderError(caughtErr, 1, 'commander.unknownOption', "error: unknown option '-m'");
   });
 
   test('when specify unknown command then throw CommanderError', () => {
@@ -65,7 +65,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops' (try '--help' for more information)");
+    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops'");
   });
 
   // Same error as above, but with custom handler.
@@ -241,6 +241,6 @@ describe('.exitOverride and error details', () => {
       caughtErr = err;
     }
 
-    expectCommanderError(caughtErr, 1, 'commander.missingMandatoryOptionValue', `error: required option '${optionFlags}' not specified (try '--help' for more information)`);
+    expectCommanderError(caughtErr, 1, 'commander.missingMandatoryOptionValue', `error: required option '${optionFlags}' not specified`);
   });
 });

From fe896d12b79231e678aee6c1c67780eec05efa6a Mon Sep 17 00:00:00 2001
From: John Gee <j.gee@adinstruments.com>
Date: Mon, 27 Jan 2020 19:08:16 +1300
Subject: [PATCH 36/37] Say "unknown command", like "unknown option"

---
 index.js                           | 2 +-
 tests/command.exitOverride.test.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index a1c5c043a..a39140bf6 100644
--- a/index.js
+++ b/index.js
@@ -1087,7 +1087,7 @@ Command.prototype.unknownOption = function(flag) {
  */
 
 Command.prototype.unknownCommand = function() {
-  const message = `error: unrecognised command '${this.args[0]}'`;
+  const message = `error: unknown command '${this.args[0]}'`;
   console.error(message);
   this._exit(1, 'commander.unknownCommand', message);
 };
diff --git a/tests/command.exitOverride.test.js b/tests/command.exitOverride.test.js
index 31cc0c015..fd75d5e3f 100644
--- a/tests/command.exitOverride.test.js
+++ b/tests/command.exitOverride.test.js
@@ -65,7 +65,7 @@ describe('.exitOverride and error details', () => {
     }
 
     expect(consoleErrorSpy).toHaveBeenCalled();
-    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unrecognised command 'oops'");
+    expectCommanderError(caughtErr, 1, 'commander.unknownCommand', "error: unknown command 'oops'");
   });
 
   // Same error as above, but with custom handler.

From 432bb5932a269be9986c417d589febe8bc58f8d2 Mon Sep 17 00:00:00 2001
From: John Gee <john@ruru.gen.nz>
Date: Tue, 28 Jan 2020 20:54:14 +1300
Subject: [PATCH 37/37] Set properties to null rather than undefined in
 constructor

---
 index.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/index.js b/index.js
index a39140bf6..dedcf936f 100644
--- a/index.js
+++ b/index.js
@@ -129,18 +129,18 @@ function Command(name) {
   this._storeOptionsAsProperties = true; // backwards compatible by default
   this._passCommandToAction = true; // backwards compatible by default
   this._actionResults = [];
-  this._actionHandler = undefined;
+  this._actionHandler = null;
   this._executableHandler = false;
-  this._executableFile = undefined; // custom name for executable
-  this._defaultCommandName = undefined;
-  this._exitCallback = undefined;
+  this._executableFile = null; // custom name for executable
+  this._defaultCommandName = null;
+  this._exitCallback = null;
 
   this._noHelp = false;
   this._helpFlags = '-h, --help';
   this._helpDescription = 'display help for command';
   this._helpShortFlag = '-h';
   this._helpLongFlag = '--help';
-  this._hasImplicitHelpCommand = undefined;
+  this._hasImplicitHelpCommand = undefined; // Deliberately undefined, not decided whether true or false
   this._helpCommandName = 'help';
   this._helpCommandnameAndArgs = 'help [command]';
   this._helpCommandDescription = 'display help for command';
@@ -202,7 +202,7 @@ Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts
   cmd._storeOptionsAsProperties = this._storeOptionsAsProperties;
   cmd._passCommandToAction = this._passCommandToAction;
 
-  cmd._executableFile = opts.executableFile; // Custom name for executable file
+  cmd._executableFile = opts.executableFile || null; // Custom name for executable file, set missing to null to match constructor
   this.commands.push(cmd);
   cmd._parseExpectedArgs(args);
   cmd.parent = this;