Does anyone know hw to treat the shinytest error?

I run recordTest() to test my little app and I got the following error below. Does any one understand the error and could tell what to do about it?


Running mytest.R setInputs(app$setInputs(btn = "click")): Server did not update any output values within 3 seconds. If this is expected, use `wait_=FALSE, values_=FALSE`, or increase the value of timeout_.
Error in sd_getAllValues(self, private, input, output, export) : 
  Unable to fetch all values from server. Is target app running with options(shiny.testmode=TRUE?)