Remove incorrect documentation about combining values and allow_blank

[eriklovmo]

The deleted example was incorrect: you can, in fact, not supply a blank value to the state parameter with such a params block. I don't know the background, maybe it was correct at one point in time.

[eriklovmo]

I did not update the changelog because it seemed like an insignificant patch. Is that OK?

[ericproulx]

@eriklovmo I do confirm the behavior

# frozen_string_literal: true

require 'bundler/inline'

gemfile(true) do
  source 'https://rubygems.org'
  gem 'grape'
  gem 'rack'
  gem 'minitest'
  gem 'rack-test'
end

require 'minitest/autorun'
require 'rack/test'
require 'grape'

class GrapeAPIBugTest < Minitest::Test
  include Rack::Test::Methods

  def setup
    @api = Class.new(Grape::API) do
      prefix :api
      version 'v1', using: :path
  
      params do
        requires :state, type: Symbol, values: [:active, :inactive]
      end
  
      post '/' do
        'hello'
      end
    end.new
  end

  def test_v1_users_via_api
    options = {
      method: Rack::POST,
      params: {
        state: nil
      }
    }
    env = Rack::MockRequest.env_for('/api/v1', options)
    response = Rack::MockResponse[*@api.call(env)]

    assert_equal 'hello', response.body
    assert_equal 201, response.status
  end
end

It fails

[ericproulx]

But #2185, is mentionning something about optional vs requires. Test is passing when updating the test with optional.

[eriklovmo]

@eriklovmo I do confirm the behavior

Thanks!

But #2185, is mentionning something about optional vs requires. Test is passing when updating the test with optional.

OK, this might warrant a clarifying note in the docs. When using optional, validation also passes when given an empty string "", which appears to be coerced into nil. I haven’t looked into the code mechanics yet, but do you think the underlying issue is the ambiguity around "blankness", or is it that we’re conflating optional keys with optional values?

@ericproulx