Expect_test_config
include Expect_test_config_types.S with type 'a IO_flush.t = 'a with type 'a IO_run.t = 'a
module IO_run : sig ... end
module IO_flush : sig ... end
val flush : unit -> unit IO_flush.t
Flush whatever need to be to get pending output out on file descriptor 0.
val run : (unit -> unit IO_run.t) -> unit
Run an IO operation until completion
Synchronous check that there is no pending output on file description 0. With async, there is no guarantee that on the rhs of a IO.bind (flush ()) ...
the output is completely flushed, that's why we need this.