Fix help default values display

index.js

@@ -1461,6 +1461,29 @@ class Command extends EventEmitter {
     return width;
   };
 
+  /**
+   * Convert value to a string for help
+   *
+   * @param {number|object|null} value
+   * @return {string}
+   */
+
+  _stringify(value) {
+    if (typeof value === 'object' && value !== null) {
+      // For arrays, simply execute this same method
+      if (Array.isArray(value)) {
+        return value.map((item) => this._stringify(item)).join(',');
+      }
+
+      // Use the `toString` method for objects that don't use the default
+      if (typeof value.toString === 'function' && Object.getPrototypeOf(value).toString !== Object.prototype.toString) {
+        return value.toString();
+      }
+    }
+
+    return JSON.stringify(value);
+  }
+
   /**
    * Return help for options.
    *
@@ -1479,7 +1502,7 @@ class Command extends EventEmitter {
     // Explicit options (including version)
     const help = this.options.map((option) => {
       const fullDesc = option.description +
-        ((!option.negate && option.defaultValue !== undefined) ? ' (default: ' + JSON.stringify(option.defaultValue) + ')' : '');
+        ((!option.negate && option.defaultValue !== undefined) ? ' (default: ' + this._stringify(option.defaultValue) + ')' : '');
       return padOptionDetails(option.flags, fullDesc);
     });
 

tests/command.help.test.js

@@ -130,3 +130,62 @@ test('when both help flags masked then not displayed in helpInformation', () =>
   const helpInformation = program.helpInformation();
   expect(helpInformation).not.toMatch('display help');
 });
+
+test('when default value is object with custom toString then custom string displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', new URL('http://example.com/'));
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).toContain('default: http://example.com/');
+});
+
+test('when default value is object without custom toString then json displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', { host: 'example.com' });
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).not.toContain('[object Object]');
+  expect(helpInformation).toContain('default: {"host":"example.com"}');
+});
+
+test('when default value is null then null displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', null);
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).toContain('default: null');
+});
+
+test('when default value is null prototype then null displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', Object.create(null));
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).toContain('default: {}');
+});
+
+test('when default value is array of object with custom toString then custom string displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', [new URL('http://example.com/'), new URL('http://example.org/')]);
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).toContain('default: http://example.com/,http://example.org/');
+});
+
+test('when default value is array of object without custom toString then json displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', [{ host: 'example.com' }, { host: 'example.org' }]);
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).not.toContain('[object Object]');
+  expect(helpInformation).toContain('{"host":"example.com"},{"host":"example.org"}');
+});
+
+test('when default value is array of object with mix of custom toString then custom string or json displays in helpInformation', () => {
+  const program = new commander.Command();
+  program
+    .option('--host <host>', 'select host', [new URL('http://example.com/'), { host: 'example.com' }]);
+  const helpInformation = program.helpInformation();
+  expect(helpInformation).not.toContain('[object Object]');
+  expect(helpInformation).toContain('http://example.com/,{"host":"example.com"}');
+});

typings/commander-tests.ts

@@ -104,13 +104,19 @@ function commaSeparatedList(value: string, dummyPrevious: string[]): string[] {
   return value.split(',');
 }
 
+function parseObject(value: string): object {
+  return JSON.parse(value);
+}
+
 const optionThis5: commander.Command = program.option('-f, --float <number>', 'float argument', parseFloat);
 const optionThis6: commander.Command = program.option('-f, --float <number>', 'float argument', parseFloat, 3.2);
 const optionThis7: commander.Command = program.option('-i, --integer <number>', 'integer argument', myParseInt);
 const optionThis8: commander.Command = program.option('-i, --integer <number>', 'integer argument', myParseInt, 5);
 const optionThis9: commander.Command = program.option('-v, --verbose', 'verbosity that can be increased', increaseVerbosity, 0);
 const optionThis10: commander.Command = program.option('-c, --collect <value>', 'repeatable value', collect, []);
 const optionThis11: commander.Command = program.option('-l, --list <items>', 'comma separated list', commaSeparatedList);
+const optionThis12: commander.Command = program.option('-o, --object <value>', 'object argument', parseObject, {});
+const optionThis13: commander.Command = program.option('-o, --object <value>', 'object argument', parseObject, null);
 
 // requiredOption, same tests as option
 const requiredOptionThis1: commander.Command = program.requiredOption('-a,--alpha');
@@ -125,6 +131,8 @@ const requiredOptionThis8: commander.Command = program.requiredOption('-i, --int
 const requiredOptionThis9: commander.Command = program.requiredOption('-v, --verbose', 'verbosity that can be increased', increaseVerbosity, 0);
 const requiredOptionThis10: commander.Command = program.requiredOption('-c, --collect <value>', 'repeatable value', collect, []);
 const requiredOptionThis11: commander.Command = program.requiredOption('-l, --list <items>', 'comma separated list', commaSeparatedList);
+const requiredOptionThis12: commander.Command = program.requiredOption('-o, --object <value>', 'object argument', parseObject, {});
+const requiredOptionThis13: commander.Command = program.requiredOption('-o, --object <value>', 'object argument', parseObject, null);
 
 // storeOptionsAsProperties
 const storeOptionsAsPropertiesThis1: commander.Command = program.storeOptionsAsProperties();