permit is checked before convert

[bbugh]

Describe the problem

When using an argument with convert :list and permit: [...], the permit is checked before the conversion.

Steps to reproduce the problem

require 'tty-option'

class Command
  include TTY::Option

  argument :fruit do
    required
    convert :list
    arity one_or_more
    permit %w[coconut mango pear] if ENV['PERMIT']
  end

  def run
    unless params.valid?
      puts params.errors.messages.join("\n")
    end

    puts params
  end
end

cmd = Command.new
cmd.parse
cmd.run

Actual behaviour

An error saying the values are unpermitted:

USE_PERMIT=true ruby test-command.rb coconut mango pear
# unpermitted value `["coconut", "mango", "pear"]` for 'fruit' argument: choose from coconut, mango, pear
# {:help=>false, :fruit=>nil}

Expected behaviour

Permit is checked after converting to a list:

ruby test-command.rb coconut mango pear
# {:help=>false, :fruit=>["coconut", "mango", "pear"]}

Describe your environment

• OS version: macOS 12.2 arm64
• Ruby version: ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [arm64-darwin21]
• TTY::Option version: 0.2.0

[piotrmurach]

Hi Brian,

Thanks for the issue report.

I don't believe this is a precedence issue. The permit checks if a value is contained within the permitted values array. In your case, you're checking if an array element is in permitted values array. This is what the error message that you have provided says as much:

# unpermitted value `["coconut", "mango", "pear"]` for 'fruit' argument: choose from coconut, mango, pear

When I designed permit method my intention was for checking a single value against a set of possible values and nothing more.

Following your example you could potentially specify conversion to a hash. How would the comparison work then? Is the hash input meant to be compared with individual elements of permitted array? That' why I added validate to specify any custom validation.