rspec_example.rb

class Object
  def should(matcher)
    if matcher.matches? self
      # ok
    else
      raise matcher.positive_failure_message
    end
  end
  
  def should_not(matcher)
    if matcher.matches? self
      raise matcher.negative_failure_message
    else
      # ok
    end
    
  end
end

class BeEqualToMatcher
  def initialize(other)
    @other = other
  end
  
  def matches?(original)
    @original = original
    @other == original
  end
  
  def negative_failure_message
    "expected #{@original.inspect} to not equal #{@other.inspect}"
  end
  
  def positive_failure_message
    "expected #{@original.inspect} to equal #{@other.inspect}"
  end
end


def be_equal_to(other)
  BeEqualToMatcher.new(other)
end



string = 'hei'
string.should be_equal_to('heiasdasd')