tests/testthat/test-delay-load.R

In reticulate: Interface to 'Python'

context("delay-load")

test_that("imported module can be customized via delay_load", {

  # ensure RETICULATE_PYTHON is set for sub-process so that
  # the expected version of Python is loaded
  config <- py_config()
  withr::local_envvar(RETICULATE_PYTHON = config$python)

  # run in a separate process, since we want the attempted module
  # load to trigger initialization of Python and so have get_module
  # handled specially
  result <- callr::r(function() {

    sys <- reticulate::import(
      "invalid_module_name",
      delay_load = list(get_module = function() { "sys" })
    )

    stopifnot(isTRUE(reticulate:::py_is_module_proxy(sys)))

    print(sys)
    stopifnot(isTRUE(reticulate::py_is_null_xptr(sys)))
    stopifnot(isTRUE(reticulate:::py_is_module_proxy(sys)))

    out <- as.character(sys$byteorder)

    stopifnot(isFALSE(reticulate::py_is_null_xptr(sys)))
    stopifnot(isFALSE(reticulate:::py_is_module_proxy(sys)))

    out
  })

  # validate expected result
  expect_true(result %in% c("little", "big"))

})