fail_with

# File lib/spec/expectations.rb, line 41
      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