Jay Fields writes an excellent module called Validatable to provide a class who include the module the ActiveRecord like behavior. For example, you can say validates_presence_of :attribute etc. This page has the RDoc of the module.When I write RSpec for a Validatable class, I ended up writing a stattement like this:

  @email.validate_only("presence_of/body")
  @email.errors.on(:body).should_not be_nil

Which is basically testing body is a required field. It works, but it looks complicated and hard to understand.The RSpec on Rails plugin provides a method error_on so that I can say something like this:

 model.should have(2).errors_on(:attribute)

This is much more readable than the previous one.I came up with a small extension on Validatable so that I can have a better syntax for testing Validatable.Here’s the spec:

require File.dirname(__FILE__) + '/../../../spec_helper'

module RspecValidatableSpec
  class Thing
    include Validatable
    attr_accessor :age
    attr_accessor :name
    validates_presence_of :age
    validates_numericality_of :age
  end
end

describe RSpecValidatable, 'a validatable object' do
  before :each do
    @thing = RspecValidatableSpec::Thing.new
  end

  it "should tell you it has at least one error on a field" do
    @thing.should have_at_least(1).error_on(:age)
  end

  it "should tell you it has one error on a required field" do
    @thing.should have(1).error_on_presence_of(:age)
  end

  it "should tell you it has one error on a numerical field" do
    @thing.should have(1).error_on_numericality_of(:age)
  end
end

describe RSpecValidatable, 'a validatable object' do
  before :each do
    @thing = RspecValidatableSpec::Thing.new
  end

  it "should tell you it has no error on a field" do
    @thing.should have(:no).errors_on(:name)
  end
end

You may need a different path to your spec_helper.rb to make it work.I got the “traditional” errors_on just like how RSpec works on ActiveRecords. What’s more, Validatable has a validates_only method which allows us validating only one type of error on one attribute. so I can have even better control than RSpec on Rails giving me over ActiveRecords. For example, I can specify what type of errors I expect to have.The only problem is that validates_only raises an error if you check an attribute on a validation that is not specified. So a nice spec like email.should have(:no).errors_on_presence_of(:attachment)is not quite possible. For those of you who are interested in this, here is the actually code:

module RSpecValidatable
  def errors_on(attribute)
    self.valid?
    [self.errors.on(attribute)].flatten.compact
  end

  def respond_to? method_name
    super(method_name) || method_name.to_s.index('error_on') == 0
  end

  def method_missing(error_on_method, attribute)
    reason = error_on_method.to_s.sub(/error_on_/, '')
    self.validate_only("#{reason.to_s}/#{attribute.to_s}")
    [self.errors.on(attribute)].flatten.compact
  end

  alias :error_on :errors_on

end

Validatable.send :include, RSpecValidatable

I need a captcha in a form, whose associated model is a Validatable. After googling, I decided to go with Simple Captcha. The Simple captcha is extremely easy to use, see its documentation, you’ll know. But it works fine with a ActiveRecord::Base, not a Validatable. There has to be some hack to make it work. I could use “Controller mode” of it. But it will be nice to put it into model, make it part of validation process. and here’s my code:

First, include SimpleCaptcha into your Validatable model:

YourValidatable.module_eval do
    class << self; include SimpleCaptcha::ModelHelpers; end
end

And overwrite apply_simple_captcha

  def self.apply_simple_captcha(options = {})
    module_eval do
      require 'pstore'
      include SimpleCaptcha::ConfigTasks
      attr_accessor :captcha, :captcha_code,
      :authenticate_with_captcha
      alias_method :valid_without_captcha?, :valid?
    end
    @captcha_invalid_message =
 (options[:message].nil? || options[:message].empty?) ?
  " image did not match with text" : options[:message]
    module_eval(turing_valid_method)
    module_eval(turing_save_method)
  end

Finally, call apply_simple_captcha

That’s it.

In the controller, instead of calling valid? to decide if the object is valid, you call valid_with_captcha?

BTW: Follow this link to see how to install RMagick on Ubuntu