Unit testing ActionCable

It seems there currently is no easy (or hard even) way to unit test ActionCable channels, which makes me very sad. There is a bit of logic in my Channels which would be very nice to cover with tests. Ideally, I’d like to have something like this:

it "rejects connection if current_user isn't the owner of the contract" do

  channel = create_channel(:contract)

  sign_in @unauthorized_user

  expect(channel.subscribe(params: {contract_id: 1}).to reject_connection


Is this something even remotely likely to happen? I googled very hard and I also checked every ActionCable issue (opened & closed) and couldn’t find anyone asking this question.