Rails RSpec I18n full error message helper for Capybara feature tests. Feels like there should be a better way, ping me if you can find one :) Stack Overflow link: http://stackoverflow.com/questions/34494599/rails-i18n-full-error-messages-in-rspec-capybara-feature-tests

helpers.rb

# spec/support/helpers.rb

require 'support/helpers/i18n_helpers'
# ...

RSpec.configure do |config|
  config.include Features::I18nHelpers, type: :feature
  # ...
end

i18n_helpers.rb

# spec/support/helpers/i18n_helpers.rb

module Features
  module I18nHelpers
    # @param [ActiveRecord::Base] model_class
    # @param [Symbol, String] attribute
    # @param [Symbol, String] message
    #
    # @return [String]
    def full_error(model_class, attribute, message)
      @_i18n_dummies ||= {}
      @_i18n_dummies[model_class] ||= model_class.new
      @_i18n_dummies[model_class].errors.full_message(
        attribute,
        @_i18n_dummies[model_class].errors.generate_message(attribute, message)
      )
    end
  end
end

post_spec.rb

# spec/features/post_spec.rb

feature 'Posts' do

  scenario 'Creating a new post'
    visit new_post_path
    click_button 'Submit'

    # Expecting an error message 'Title can't be blank'
    expect(page).to have_content full_error(Post, :title, :blank)
  end

end

When having nested attributes, the error message is prefixed with the model name, and thus the attribute passed to full_message should be prefixed.

So I've updated it to the following:

    # error messages for nested attributes are prefixed with the model name
    attr_name = attribute.to_s.split('.').last
    @_i18n_dummies[model_class].errors.full_message(
      attribute,
      @_i18n_dummies[model_class].errors.generate_message(attr_name, message)
    )

And usage:

expect(page).to have_content full_error(Post, :"post.title", :blank)

@koenpunt AFAIK since the receiver of #generate_message is @_i18n_dummies[model_class].errors, it's already scoped to the relevant model class. The original code should work if called like full_error(Post, :title, :blank).

full_error(Page, :title, :blank) # => "Başlık doldurulmalı"
full_error(User, :title, :blank) # => "Unvan doldurulmalı"
# (a page title and a user title (position name) are different words in Turkish)