shiny/tests/testthat/test-bind-event.R

# Note that there are some tests for bindEvent() and caching in
# test-with-cache.R.

test_that("bindEvent and observers", {
  trigger <- reactiveVal(1)
  val <- reactiveVal(10)

  vals <- numeric()
  o <- bindEvent(
    trigger(),
    x = observe({
      vals <<- c(vals, val())
    })
  )

  flushReact()
  expect_identical(vals, 10)

  # Changing val has no effect
  val(20)
  flushReact()
  expect_identical(vals, 10)

  # Changing trigger causes the observer to execute
  trigger(2)
  flushReact()
  expect_identical(vals, c(10, 20))

  trigger(3)
  flushReact()
  expect_identical(vals, c(10, 20, 20))
})


test_that("bindEvent alters observers in place", {
  v <- reactiveVal(1)
  o <- observe({ v() })
  o1 <- bindEvent(o, v())

  # o and o1 are the same object
  expect_identical(o, o1)

  # Can't call bindEvent twice on an observer
  expect_error(bindEvent(o, v()))
})


test_that("ignoreNULL works", {
  n <- 0
  observe({ n <<- n+1 }) %>% bindEvent(NULL, ignoreNULL = FALSE)
  flushReact()
  expect_identical(n, 1)

  n <- 0
  observe({ n <<- n+1 }) %>% bindEvent(NULL, ignoreNULL = TRUE)
  flushReact()
  expect_identical(n, 0)

  # Two NULLs in the `...` get aggregated into a list, so the result is not
  # NULL.
  n <- 0
  observe({ n <<- n+1 }) %>% bindEvent(NULL, NULL, ignoreNULL = TRUE)
  flushReact()
  expect_identical(n, 1)
})


test_that("once=TRUE works", {
  n <- 0
  v <- reactiveVal(1)
  observe({ n <<- n + 1 }) %>% bindEvent(v(), once = FALSE)
  flushReact()
  expect_identical(n, 1)
  v(2)
  flushReact()
  expect_identical(n, 2)

  n <- 0
  v <- reactiveVal(1)
  observe({ n <<- n + v() }) %>% bindEvent(v(), once = TRUE)
  flushReact()
  expect_identical(n, 1)
  v(2)
  flushReact()
  expect_identical(n, 1)
})