• Polls the provided stream and expects a non-null item to be produced.
  • Polls the provided stream and expects that it is Pending (e.g no stream items).
  • ! Utilities for tests Run a background task while waiting for a future that should occur. This is useful for running a task which you expect to produce side effects that mean the task is operating correctly. i.e. reacting to a peer action by producing a response on a client’s hanging get. background_fut is expected not to finish ans is returned to the caller, along with the result of result_fut. If background_fut finishes, this function will panic.