class RSpec::Matchers::BuiltIn::Exist::ExistenceTest

def validity_message
  case uniq_truthy_values.size
  when 0
    " but it does not respond to either `exist?` or `exists?`"
  when 2
    " but `exist?` and `exists?` returned different values:\n\n"\
    " exist?: #{existence_values.first}\n"\
    "exists?: #{existence_values.last}"
  end
end