tests/testthat/test-download_file_linter.R

In lintr: A 'Linter' for R Code

test_that("download_file_linter skips allowed usages", {
  linter <- download_file_linter()

  expect_no_lint("download.file(x, mode = 'wb')", linter)
  expect_no_lint("download.file(x, mode = 'ab')", linter)

  # 'w' or 'a' but passed to different arguments
  expect_no_lint("download.file(x, destfile = 'w', mode = 'wb')", linter)
  expect_no_lint("download.file(x, mode = 'wb', method = 'internal', quiet = TRUE, 'w')", linter)

  # if mode = "wget" or "curl", mode is ignored so we don't lint on the default
  expect_no_lint("download.file(x, method = 'curl')", linter)
  expect_no_lint("download.file(x, method = 'wget')", linter)

  expect_no_lint("download.file(x, method = 'internal', mode = 'wb')", linter)
  expect_no_lint("download.file(x, method = method, mode = 'wb')", linter)
})

test_that("download_file_linter blocks simple disallowed usages", {
  linter <- download_file_linter()
  lint_message <- rex::rex("download.file() should use mode =")

  # Case 1: implicit default (mode = "w")
  expect_lint("download.file(x)", lint_message, linter)
  expect_lint("download.file(x, method = 'internal')", lint_message, linter)

  # Case 2: non-portable mode specified by name
  expect_lint("download.file(x, mode = 'w')", lint_message, linter)
  expect_lint("download.file(x, mode = 'a')", lint_message, linter)
  expect_lint("download.file(x, method = method, mode = 'w')", lint_message, linter)

  # 'wb' passed to different argument
  expect_lint("download.file(x, mode = 'w', method = 'internal', quiet = TRUE, 'wb')", lint_message, linter)
  expect_lint("download.file(cacheOK = TRUE, destfile, method, quiet, x = 'wb')", lint_message, linter)

  # mode explicitly specified with a method that ignores it
  lint_message <- rex::rex("mode argument value is ignored")
  expect_lint("download.file(x, method = 'wget', mode = 'w')", lint_message, linter)
  expect_lint("download.file(x, method = 'curl', mode = 'wb')", lint_message, linter)
})

test_that("lints vectorize", {
  expect_lint(
    trim_some("{
      download.file(x, mode = 'w')
      download.file(y, mode = 'a')
      download.file(z, mode = 'wb', method = 'curl')
    }"),
    list(
      list(
        rex::rex("download.file() should use mode = 'wb'"),
        line_number = 2L
      ),
      list(
        rex::rex("download.file() should use mode = 'ab'"),
        line_number = 3L
      ),
      list(
        rex::rex("mode argument value is ignored"),
        line_number = 4L
      )
    ),
    download_file_linter()
  )
})