class RSpec::Matchers::DSL::Matcher

def respond_to_missing?(method, include_private=false)

Also, supports getting a method object for such methods.
from the `@matcher_execution_context` as well.
Indicates that this matcher responds to messages
def respond_to_missing?(method, include_private=false)
  super || @matcher_execution_context.respond_to?(method, include_private)
end