test_that("backport_linter produces error when R version misspecified", {
  expect_error(
    lint(text = "numToBits(2)", linters = backport_linter(420L)),
    "`r_version` must be a R version number, returned by R_system_version(), or a string.",
    fixed = TRUE
  )
})

test_that("backport_linter detects backwards-incompatibility", {
  # default should be current R version; all of these are included on our dependency
  expect_lint(".getNamespaceInfo(dir.exists(lapply(x, toTitleCase)))", NULL, backport_linter())
  expect_lint(".getNamespaceInfo(dir.exists(lapply(x, toTitleCase)))", NULL, backport_linter("release"))
  expect_lint(".getNamespaceInfo(dir.exists(lapply(x, toTitleCase)))", NULL, backport_linter("devel"))

  expect_lint(
    "numToBits(2)",
    rex::rex("numToBits (R 4.1.0) is not available for dependency R >= 4.0.0."),
    backport_linter("4.0.0")
  )
  # symbols as well as calls
  expect_lint(
    "lapply(1:10, numToBits)",
    rex::rex("numToBits (R 4.1.0) is not available for dependency R >= 4.0.0."),
    backport_linter("4.0.0")
  )

  expect_lint(
    "trimws(...names())",
    list(
      rex::rex("trimws (R 3.2.0) is not available for dependency R >= 3.0.0."),
      rex::rex("...names (R 4.1.0) is not available for dependency R >= 3.0.0.")
    ),
    backport_linter("3.0.0")
  )

  # oldrel specification
  expect_lint(
    ".pretty(2)",
    rex::rex(".pretty (R 4.2.0) is not available for dependency R >= 4.1.3."),
    backport_linter("oldrel")
  )

  expect_error(backport_linter("oldrel-99"), "`r_version` must be a version number or one of")

  expect_lint(
    "numToBits(2)",
    rex::rex("numToBits (R 4.1.0) is not available for dependency R >= 3.6.3."),
    backport_linter("oldrel-3")
  )

  # except is honored
  expect_lint(
    trim_some("
      numToBits(2)
      R_user_dir('mypkg')
    "),
    NULL,
    backport_linter("3.0.0", except = c("numToBits", "R_user_dir"))
  )
})

test_that("backport_linter generates expected warnings", {
  tmp <- withr::local_tempfile(lines = "x <- x + 1")

  expect_warning(
    {
      l <- lint(tmp, backport_linter("2.0.0"))
    },
    "version older than 3.0.0",
    fixed = TRUE
  )
  expect_identical(l, lint(tmp, backport_linter("3.0.0")))
})