tests/testthat/test-callback-helpers.R

In vegawidget/vegawidget: 'Htmlwidget' for 'Vega' and 'Vega-Lite'

library("withr")

# establish V8 session
ct <- V8::v8()
ct$source(system.file("bin", "vega_to_svg_v8.js", package = "vegawidget"))

test_that("vw_fetch() works", {

  expect_snapshot(
    vw_fetch("https://vega.github.io/vega-datasets/data/anscombe.json")
  )

  # check using V8
  # for syntax, see https://stackoverflow.com/a/49938734

  # make sure it works with json (needs to be parsed)
  expect_snapshot({
    ct$assign("url", "https://vega.github.io/vega-datasets/data/anscombe.json")
    ct$eval(
      "(async () => {result = await vwFetch(url, {response: 'json'});})()"
    )
    ct$eval("console.log(JSON.stringify(result))")
  })

  # make sure it works with text
  expect_snapshot({
    ct$assign("url", "https://vega.github.io/vega-datasets/data/seattle-weather.csv")
    ct$eval(
      "(async () => {result = await vwFetch(url, {response: 'text'});})()"
    )
    ct$eval("console.log(result)")
  })

})

test_that("vw_load() works", {

  tmpfile <- local_tempfile()

  # get rid of any backslashes (Windows)
  # we will have to keep that in mind in vw_to_svg()
  tmpfile <- gsub("\\\\", "/", tmpfile)

  writeLines("foobar", tmpfile)

  expect_snapshot(
    vw_load(tmpfile)
  )

  # check using V8
  expect_snapshot(
    ct$eval(
      glue_js("(async () => {console.log(await vwLoad('${tmpfile}'))})()")
    )
  )
})