Add support for help groups for options

[shadowspawn]

Pull Request

Problem

See: #1897
Related PR: #1908 #1910

Solution

This is a proof of concept adding a map of group titles to the Help configuration. This sort of mapping has some advantages compared with adding a group property to each Option:

• specify group title once instead of multiple times
• support for grouping help and version without needing to create custom Options
• support for grouping user-created options without needing to create custom Options
• (for Command groups, would support putting external commands into groups without extra work)

However, directly supplying the map does not feel very Commander-like. Adding a method on Command to add a single option group at a time might be more in the chaining style while retaining the practical advantages. Adding a group property to the Option would be more object-oriented, and other libraries allow this (#1897 (comment)).

Playing with the idea partly to think about how Help could be refactored to make this more feasible to implement with an author supplied override.

Example use:

const { program, Option } = require('commander');

program
  .option('-c, --carbon')
  .option('-r, --rabbit', 'cudly little friends')
  .option('-o, --oxygen')
  .addOption(new Option('-s, --sheep'))
  .option('--no-sheep') // negated
  .option('-n', 'neon') // short
  .option('--armadillo') // long
  .option('--zzz')
  .option('--dog', 'faithful furry companions')
  .option('--no-dog')

program.configureHelp({
  optionGroups: {
    'Animal Options:': ['rabbit', 'armadillo', 'sheep', 'dog'],
    'Element Options:': ['carbon', 'oxygen', 'n' /* neon */],
    'Help Options:': ['help']
    }
  }),

program.parse();

% node map2-options.js --help
Usage: map2-options [options]

Options:
  --zzz

Animal Options:
  -r, --rabbit  cudly little friends
  -s, --sheep
  --no-sheep
  --armadillo
  --dog         faithful furry companions
  --no-dog

Element Options:
  -c, --carbon
  -o, --oxygen
  -n            neon

Help Options:
  -h, --help    display help for command

[shadowspawn]

Decent proof of concept. Still wishing was easier for authors to customise the behaviour in large formatHelp without copying.

A defect in this PR is using .configureHelp() in a subcommand to get grouping will replace (lose) other changes made at root level.