fix showing help for sub commands with custom executableFile

[nazieb]

Problem

As of 3.0.0, the git-style executable sub commands can have executableFile option to customize the name of file containing the command.

But running help for these kind of sub commands will return error as the built-in help sub command will try to look executable files with default constructed name.

Example in old version:

program
  .version('0.0.1')
  .command('specifyInstall', 'specify install subcommand', { executableFile: 'pm-install' })

$ ./pm help specifyInstall
error: pm-specifyInstall(1) does not exist, try --help

Solution

Turns out, this is because when we run help, it will be treated as any user defined sub commands with special treatment of switching the arguments in the executeSubCommand function to make it as if we run our custom sub command using --help flag (see here).

This is incorrect behaviour since the executeSubCommand will further assume the executable file name with default constructed name, as the resolving mechanism of the executableFile option is done at the parse function.

This PR fixes the problem by moving the "argument switching" mechanism to the parse function before the resolving mechanism is done, so the executeSubCommand will get correct executable file name.

[shadowspawn]

Thank-you for identifying the issue, the PR, and good description.

I have not looked at where the code moved to yet, but a concern I have from description is whether this will affect .action based commands. I'll work it out quickly when I look, but wanted to mention it.

[shadowspawn]

(Does not change action parsing.)

[nazieb]

@shadowspawn thanks for your review 🙇‍♂️

[abetomo]

Thank you!