Long story. This is not quite right, but works in simple cases. I think there are less code changes required.

The strip-dashed spelling appearing in the "aliases" is a bit of cheat, it only appears in the parse results and is not recognised on the command-line and does not match what is on the command-line.

I added some trace statements to double-check my expectations. (I have a -d, --debug boolean option in my test program.)

At this original line:

      const requestCompletions = this.#completion!.completionKey in argv;

argv is the parse result from calling yargs-parser internally, so with default options:

$ node index.js --get-yargs-completions --debug
{
  argv: {
    _: [],
    'get-yargs-completions': true,
    getYargsCompletions: true,
    debug: true,
    d: true,
    '$0': 'index.js'
  }
}

To cope with the author changing the parser configuration, we need to be flexible about what the property got called in the parse results.

Later at this point:

        const completionArgs = args.slice(
           args.indexOf(`--${this.#completion!.completionKey}`) + 1
         );

args is the original command-line args like:

$ node index.js --get-yargs-completions --debug
{ args: [ '--get-yargs-completions', '--debug' ] }

Here, we still want to check for the original unaltered this.#completion!.completionKey no matter what "alias" we found in argv. With 'strip-dashed': true the new code looks for the stripped name and fails to remove the dashed argument.

So requestCompletions should stay just a boolean, and only that initial calculation changes. I think you can just change .find() to .some() to match the semantics. We don't care which variation was found.

This is because the completion feature relies on passing '--get-yargs-completions' verbatim to yargs.

This assumption is ok. The cause of the bug you observed is that the option name got changed in the parse results by the parser configuration settings, and fooled yargs.

Good description with the PR, and added a test covering multiple configurations. Nice work.

Thanks for the help @shadowspawn!

Once it is merged, do you know when the next release would be? I've admittedly not paid too much attention to the yargs release schedule in the past.

I am guessing next release 1-2 months after last release (which was 2023-04-27).