Test unique attributes with RSpec and accept_values_for, a custom matcher

gistfile1.txt

class CourseItem < ActiveRecord::Base
  validates_presence_of :course_id, :day, :url
  validates_uniqueness_of :course_id, :scope => :day, :message => "- this day has been already created."
end

describe CourseItem do
  # check uniqueness using this matcher https://github.com/bogdan/accept_values_for
  context "should create one item per day and per course only" do
    before do
      CourseItem.create! :day => 1, :course_id => 1, :url => '/courses/index.html'
    end
    
    it { should_not accept_values_for(:day => 1, :course_id => 1) }
  end
end