class RSpec::Expectations::LegacyMatcherAdapter::RSpec1

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