# File lib/mspec/expectations/should.rb, line 15
15:   def should_not(matcher=NO_MATCHER_GIVEN)
16:     MSpec.expectation
17:     MSpec.actions :expectation, MSpec.current.state
18:     unless matcher.equal?(NO_MATCHER_GIVEN)
19:       if matcher.matches?(self)
20:         SpecExpectation.fail_with(*matcher.negative_failure_message)
21:       end
22:     else
23:       SpecNegativeOperatorMatcher.new(self)
24:     end
25:   end