Writing testServer() tests for modules using ExtendedTask

[karawoo]

I'm adding ExtendedTasks to a module that has testServer tests for some of the reactives. I'm curious if there's any way to test the outputs of an ExtendedTask in testServer? I realize I may be after contradictory things here and this may not be possible.

The example below doesn't work, which makes sense since expect_equal() is called before the ExtendedTask returns a result. I thought maybe setting the future plan to "sequential" would make it work, but it didn't.

library("shiny")
library("promises")
library("testthat")

future::plan("multisession")

server <- function(input, output, session) {
  sum_values <- ExtendedTask$new(function(x, y) {
    future_promise({
      Sys.sleep(5)
      x + y
    })
  })
  observeEvent(input$button, {
    sum_values$invoke(input$x, input$y)
  })
}

testServer(server, {
  session$setInputs(
    x = 1,
    y = 2,
    button = 1
  )
  expect_equal(sum_values$result(), 3)
})

I also tried putting the following before the expect_equal() just to check on the task's status and it seems to stay in "running" for the whole minute.

i <- 1
while (sum_values$status() %in% c("initial", "running") && i < 60) {
  Sys.sleep(1)
  print(paste(i, sum_values$status()))
  i <- i + 1
}

[stla]

I don't know, but don't you need a bind_task_button?

[karawoo]

I don't think so? bind_task_button() disables the button in the UI while the ExtendedTask is processing, which is not necessary for this minimal reprex since there is no UI.

[stla]

Sorry for not being helpful. The only thing I know is that there's a way to test ExtendedTask with the shinytest2 package. But as I understand, this requires the bslib button.