require 'spec/matchers'
require 'spec/expectations/errors'
require 'spec/expectations/extensions'
require 'spec/expectations/handler'

module Spec
  
  # Spec::Expectations lets you set expectations on your objects.
  #
  #   result.should == 37
  #   team.should have(11).players_on_the_field
  #
  # == How Expectations work.
  #
  # Spec::Expectations adds two methods to Object:
  #
  #   should(matcher=nil)
  #   should_not(matcher=nil)
  #
  # Both methods take an optional Expression Matcher (See Spec::Matchers).
  #
  # When +should+ receives an Expression Matcher, it calls <tt>matches?(self)</tt>. If
  # it returns +true+, the spec passes and execution continues. If it returns
  # +false+, then the spec fails with the message returned by <tt>matcher.failure_message</tt>.
  #
  # Similarly, when +should_not+ receives a matcher, it calls <tt>matches?(self)</tt>. If
  # it returns +false+, the spec passes and execution continues. If it returns
  # +true+, then the spec fails with the message returned by <tt>matcher.negative_failure_message</tt>.
  #
  # RSpec ships with a standard set of useful matchers, and writing your own
  # matchers is quite simple. See Spec::Matchers for details.
  module Expectations
    class << self
      attr_accessor :differ

      # raises a Spec::Expectations::ExpectationNotMetError with message
      #
      # When a differ has been assigned and fail_with is passed
      # <code>expected</code> and <code>target</code>, passes them
      # to the differ to append a diff message to the failure message.
      def fail_with(message, expected=nil, target=nil) # :nodoc:
        if Array === message && message.length == 3
          message, expected, target = message[0], message[1], message[2]
        end
        unless (differ.nil? || expected.nil? || target.nil?)
          if expected.is_a?(String)
            message << "\nDiff:" << self.differ.diff_as_string(target.to_s, expected)
          elsif !target.is_a?(Proc)
            message << "\nDiff:" << self.differ.diff_as_object(target, expected)
          end
        end
        Kernel::raise(Spec::Expectations::ExpectationNotMetError.new(message))
      end
    end
  end
end