lib: add support for auto-injecting help option and return help text in parseArgs

Author: miguelmarcondesf

lib/internal/util/parse_args/parse_args.js

@@ -348,8 +348,25 @@ const parseArgs = (config = kEmptyObject) => {
   const allowPositionals = objectGetOwn(config, 'allowPositionals') ?? !strict;
   const returnTokens = objectGetOwn(config, 'tokens') ?? false;
   const allowNegative = objectGetOwn(config, 'allowNegative') ?? false;
-  const options = objectGetOwn(config, 'options') ?? { __proto__: null };
+  let options = objectGetOwn(config, 'options') ?? { __proto__: null };
   const help = objectGetOwn(config, 'help') ?? '';
+
+  const hasGenerateHelp = help.length > 0;
+  const addHelpOption = objectGetOwn(config, 'addHelpOption') ?? hasGenerateHelp;
+  const returnHelpText = objectGetOwn(config, 'returnHelpText') ?? (hasGenerateHelp || addHelpOption);
+
+  // Auto-inject help option if requested and not already present
+  if (addHelpOption && !ObjectHasOwn(options, 'help')) {
+    options = {
+      ...options,
+      __proto__: null,
+      help: {
+        type: 'boolean',
+        short: 'h',
+        help: 'Show help',
+      },
+    };
+  }
   // Bundle these up for passing to strict-mode checks.
   const parseConfig = { args, strict, options, allowPositionals, allowNegative };
 
@@ -361,6 +378,8 @@ const parseArgs = (config = kEmptyObject) => {
   validateBoolean(allowNegative, 'allowNegative');
   validateObject(options, 'options');
   validateString(help, 'help');
+  validateBoolean(addHelpOption, 'addHelpOption');
+  validateBoolean(returnHelpText, 'returnHelpText');
   ArrayPrototypeForEach(
     ObjectEntries(options),
     ({ 0: longOption, 1: optionConfig }) => {
@@ -447,22 +466,24 @@ const parseArgs = (config = kEmptyObject) => {
     }
   });
 
-  // Phase 4: generate print usage for each option
-  let printUsage = '';
-  if (help) {
-    printUsage += help;
-  }
-  ArrayPrototypeForEach(ObjectEntries(options), ({ 0: longOption, 1: optionConfig }) => {
-    const helpTextForPrint = formatHelpTextForPrint(longOption, optionConfig);
+  // Phase 4: generate print usage for each option if requested
+  if (returnHelpText) {
+    let printUsage = '';
+    if (help) {
+      printUsage += help;
+    }
+    ArrayPrototypeForEach(ObjectEntries(options), ({ 0: longOption, 1: optionConfig }) => {
+      const helpTextForPrint = formatHelpTextForPrint(longOption, optionConfig);
+
+      if (printUsage.length > 0) {
+        printUsage += '\n';
+      }
+      printUsage += helpTextForPrint;
+    });
 
     if (printUsage.length > 0) {
-      printUsage += '\n';
+      result.helpText = printUsage;
     }
-    printUsage += helpTextForPrint;
-  });
-
-  if (help && printUsage.length > 0) {
-    result.values.help = printUsage;
   }
 
   return result;