anchor.diff:      start ()
   
     override this.Dispose() =
  -    subscription.Dispose()
  +    disposables.Dispose()
  
positive.code: type FileLoadingPermanentTestAssembly(notifier: Notifier, file: FileInfo) =
    inherit PermanentTestAssembly()
  
    let currentTestAssembly =
      ReactiveProperty.create (None: option<OneshotTestAssembly>)
  
    let cancel () =
      match currentTestAssembly.Value with
      | Some testAssembly ->
        testAssembly.Dispose()
        currentTestAssembly.Value <- None
      | None -> ()
  
    let cancelCommand =
      currentTestAssembly
  
negative.code:       )
      |> Observable.switch
  
    let start () =
      reloadRequested.OnNext(())
      file |> FileInfo.subscribeChanged (TimeSpan.FromMilliseconds(100.0))
        (fun () -> reloadRequested.OnNext(()))
      |> disposables.Add
  
    do
      currentTestAssembly
      |> Observable.choose id
      |> Observable.subscribe (fun testAssembly -> testAssembly.Start())
      |> ignore
  
    override this.CancelCommand =
      cancelCommand
  