class RSpec::Expectations::LegacyMatcherAdapter::RSpec1

@private
* ‘negative_failure_message`
* `failure_message`
Before RSpec 1.2, the failure message protocol was:

def self.interface_matches?(matcher)

for `failure_message` here.
(paired with `failure_message_when_negated`), so we don't check
Note: `failure_message` is part of the RSpec 3 protocol 
def self.interface_matches?(matcher)
  !matcher.respond_to?(:failure_message_when_negated) &&
  matcher.respond_to?(:negative_failure_message)
end

def failure_message 

def failure_message
  base_matcher.failure_message
end

def failure_message_when_negated 

def failure_message_when_negated
  base_matcher.negative_failure_message
end