Specifying both `count` and `boolean` should throw error

[hildjj]

As discussed in yargs/yargs#256, specifying both count and boolean is a programming error. yargs should throw an exception, or at the very least print a warning. If printing a warning is chosen, the default count should be 0 instead of 2 (as is currently the case).

[plroebuck]

This is still broken as of yargs-v11.0.0.
Should throw an exception if .boolean() method is used with .count() for the same option.

#!/usr/bin/env node
'use strict';

var argv = require('yargs')
  .options({
    'verbose': {
      description: 'Set verbosity level',
      boolean: true,
      count: true,
      alias: 'v'
    }
  })
  .help('help', 'Show usage information and exit')
  .argv;

console.log(argv.verbose);  // outputs 2+count(v)

$ expect="3"
$ out=$(bin/testme -vvv)
$ if [ "${expect}" = "${out}" ]; then echo "success"; else echo "failed: expect=${expect}, actual=${out}"; fi
failed: expect=3, actual=5

[bcoe]

@hildjj @plroebuck let's start by printing a warning if you use two mutually exclusive options in yargs ... this will encourage folks to stop doing so, but will allow us to release the update without it being a breaking change.

I bet there are a few other combinations of options we could come up with that shouldn't be possible in conjunction, so we should try to write this warning mechanism in a way that's easy to sprinkle throughout the codebase.

I would love help working on this issue, if either of you are interested?

[bcoe]

@juergba has been starting to add some of this validation logic, see:

#191