Rails Custom URL Validator

url_validator.rb

class UrlValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    record.errors[attribute] << (options[:message] || "must be a valid URL") unless url_valid?(value)    
  end
  
  # a URL may be technically well-formed but may not actually be
  # valid, so this checks for both.
  def url_valid?(url)
    url = URI.parse(url) rescue false
    url.kind_of?(URI::HTTP) || url.kind_of?(URI::HTTPS)
  end 
end

url_validator_spec.rb

describe UrlValidator do

  before do
    @validator = UrlValidator.new attributes: {}
  end

  context 'invalid input' do
    it 'should return false for a poorly formed URL' do
      @validator.url_valid?('something.com').should be_false
    end

    it 'should return false for garbage input' do
      pi = 3.14159265
      @validator.url_valid?(pi).should be_false
    end

    it 'should return false for URLs without an HTTP protocol' do
      @validator.url_valid?('ftp://secret-file-stash.net').should be_false
    end
  end

  context 'valid input' do
    it 'should return true for a correctly formed HTTP URL' do
      @validator.url_valid?('http://nooooooooooooooo.com').should be_true
    end

    it 'should return true for a correctly formed HTTPS URL' do
      @validator.url_valid?('https://google.com').should be_true
    end
  end

end

Trying to run with Rails 4 as is, test fails with -

UrlValidator
  invalid input
    should return false for a poorly formed URL (FAILED - 1)

Failures:

  1) UrlValidator invalid input should return false for a poorly formed URL
     Failure/Error: @validator = UrlValidator.new attributes: {}
     ArgumentError:
       :attributes cannot be blank
     # ./spec/models/url_validator_spec.rb:4:in `new'
     # ./spec/models/url_validator_spec.rb:4:in `block (2 levels) in <top (required)>'
     # -e:1:in `<main>'

Fix -

  before do
    @validator = UrlValidator.new attributes: { url: '' }
  end