anchor.diff:      |> ReactiveProperty.ofObservable TestSuiteSchema.empty
   
     let schemaUpdated =
  -    currentTestSchema.Pairwise()
  +    currentTestSchema
  +    |> Observable.pairwise
       |> Observable.map
  -      (fun pair ->
  -        TestSuiteSchema.difference pair.OldItem pair.NewItem
  +      (fun (oldSchema, newSchema) ->
  +        TestSuiteSchema.difference oldSchema newSchema
         )
   
     let testCompleted =
  
positive.code:     start ()
  
    override this.Dispose() =
      subscription.Dispose()
  
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
  