class RSpec::Rails::Matchers::ActionCable::HaveStream

def match(subscription)
  case subscription
  when ::ActionCable::Channel::Base
    @actual = subscription.streams
    no_expected? ? actual.any? : actual.any? { |i| expected === i }
  else
    raise ArgumentError, "have_stream, have_stream_from and have_stream_from support expectations on subscription only"
  end
end