Mike Vincent

# my_matchers.rb
module My
  module SpecMatchers    
    class UnsavedRecord < StandardError; end
    class HaveAUnique  #:nodoc:

      def initialize(attribute, opts = {})
        @attribute = attribute
        @options = {:case_sensitive => true}.merge(opts)
      end

      def matches?(obj)
        raise UnsavedRecord, "Can only check uniqueness against saved records, save your object first." if obj.new_record?
        @value = obj.send(@attribute)
        klass = obj.class
        new_obj = klass.new(@attribute => @value)
        new_obj.valid?
        ok = !new_obj.errors[@attribute].nil?
        # check if it should be unique even with different casing
        if ok && !@options[:case_sensitive]
          new_obj = klass.new(@attribute => flip_case(@value))
          new_obj.valid?
          ok = !new_obj.errors[@attribute].nil?
        end
        ok
      end

      def flip_case(string)
        string.size.times do |i|
          string[i] = string[i].chr.send(:upcase) == string[i].chr ? string[i].chr.send(:downcase) : string[i].chr.send(:upcase)
        end
        string
      end

      def failure_message
        msg = "expected #{@attribute} to be unique, but was able to create another object having #{@attribute} => #{@value} without errors\n"
      end

      def negative_failure_message
        failure_message
      end

      def description
        "unique attribute value"
      end

    end

    def have_a_unique(*exp)
      HaveAUnique.new(*exp)
    end

  end
end

# somewhere in my spec/spec_helper.rb
require File.dirname(__FILE__) + '/my_matchers.rb'

# Open up the behaviors api and stick our custom matchers in
# module Spec::DSL::BehaviourAp
# update: r2536 in rspec trunk renamed BehaviorApi to ExampleApi, so now it's...
module Spec::DSL::ExampleApi
  def before_eval
    module_eval do 
      include My::SpecMatchers
    end
  end
end

# I -think- this is how you'd do it using rspec versions < 1.0.8
# the project I did this within, I'm using trunk. 
# class Spec::DSL::Behaviour
#   def before_eval
#     @eval_module.include My::SpecMatchers
#   end
# end

describe Sompn do
  before do
    @sompn = Sompn.create!(:name => 'foo', :phone => '123-555-1212')
  end

  it "should have a unique case insensitive name" do
    @sompn.should have_a_unique(:name, :case_sensite => false)
  end

  it "should have a unique phone" do
    @sompn.should have_a_unique(:phone)
  end
end

    # Have a ....
    class HaveA #:nodoc:

      def initialize(attribute, opts = {})
        @attribute = attribute
        @options = {:required => false}.merge(opts)
      end

      def matches?(obj)
        @klass = obj.class
        @exist = obj.respond_to?(@attribute.to_sym)
        if @options[:required]
          obj.send("#{@attribute}=",nil) 
          obj.valid?
          return !obj.errors[@attribute].nil?
        end
        @exist
      end

      def failure_message
        if @options[:required] && @exist
          "expected #{@attribute} to be required but having a nil value is valid"
        else
          "expected #{@klass} object to respond to #{@attribute}"
        end
      end

      def negative_failure_message
        failure_message
      end

      def description
        "unique attribute value"
      end

    end

    def have_a(*exp)
      HaveA.new(*exp)
    end

describe Sompn do
  it "should have a foo, but not require it" do
    @sompn.should have_a(:foo)
  end

  it "should require a bar" do
    @sompn.should have_a(:bar, :required => true)
  end
end