tests/testthat/test-seq_linter.R

In lintr: A 'Linter' for R Code

test_that("other : expressions are fine", {
  linter <- seq_linter()
  expect_lint("function() { 1:10 }", NULL, linter)
  expect_lint("function(x) { 2:length(x) }", NULL, linter)
  expect_lint("function(x) { 1:(length(x) || 1) }", NULL, linter)
})

test_that("seq_len(...) or seq_along(...) expressions are fine", {
  linter <- seq_linter()

  expect_lint("function(x) { seq_len(x) }", NULL, linter)
  expect_lint("function(x) { seq_along(x) }", NULL, linter)

  expect_lint("function(x) { seq(2, length(x)) }", NULL, linter)
  expect_lint("function(x) { seq(length(x), 2) }", NULL, linter)
})

test_that("finds seq(...) expressions", {
  linter <- seq_linter()

  expect_lint(
    "function(x) { seq(length(x)) }",
    rex::rex("seq(length(...))", anything, "Use seq_along(...)"),
    linter
  )

  expect_lint(
    "function(x) { seq(nrow(x)) }",
    rex::rex("seq(nrow(...))", anything, "Use seq_len(nrow(...))"),
    linter
  )

  expect_lint(
    "function(x) { rev(seq(length(x))) }",
    rex::rex("seq(length(...))", anything, "Use seq_along(...)"),
    linter
  )

  expect_lint(
    "function(x) { rev(seq(nrow(x))) }",
    rex::rex("seq(nrow(...))", anything, "Use seq_len(nrow(...))"),
    linter
  )
})

test_that("finds 1:length(...) expressions", {
  linter <- seq_linter()

  expect_lint(
    "function(x) { 1:length(x) }",
    rex::rex("length(...)", anything, "Use seq_along"),
    linter
  )

  expect_lint(
    "function(x) { 1:nrow(x) }",
    rex::rex("nrow(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { 1:ncol(x) }",
    rex::rex("ncol(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { 1:NROW(x) }",
    rex::rex("NROW(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { 1:NCOL(x) }",
    rex::rex("NCOL(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { 1:dim(x)[1L] }",
    rex::rex("dim(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { 1L:dim(x)[[1]] }",
    rex::rex("dim(...)", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { mutate(x, .id = 1:n()) }",
    rex::rex("n() is", anything, "Use seq_len"),
    linter
  )

  expect_lint(
    "function(x) { x[, .id := 1:.N] }",
    rex::rex(".N is", anything, "Use seq_len"),
    linter
  )
})

test_that("1L is also bad", {
  expect_lint(
    "function(x) { 1L:length(x) }",
    rex::rex("1L:length(...)", anything, "Use seq_along"),
    seq_linter()
  )
})

test_that("reverse seq is ok", {
  linter <- seq_linter()
  expect_lint("function(x) { rev(seq_along(x)) }", NULL, linter)
  expect_lint("function(x) { rev(seq_len(nrow(x))) }", NULL, linter)

  expect_lint(
    "function(x) { length(x):1 }",
    rex::rex("length(...):1", anything, "Use rev(seq_along(...))"),
    seq_linter()
  )
})

test_that("Message vectorization works for multiple lints", {
  expect_lint(
    "c(1:length(x), 1:nrow(y))",
    list(
      rex::rex("1:length(...)", anything, "seq_along(...)"),
      rex::rex("1:nrow(...)", anything, "seq_len(nrow(...))")
    ),
    seq_linter()
  )

  expect_lint(
    "c(seq(length(x)), 1:nrow(y))",
    list(
      rex::rex("seq(length(...))", anything, "seq_along(...)"),
      rex::rex("1:nrow(...)", anything, "seq_len(nrow(...))")
    ),
    seq_linter()
  )

  expect_lint(
    "c(seq(length(x)), seq(nrow(y)))",
    list(
      rex::rex("seq(length(...))", anything, "seq_along(...)"),
      rex::rex("seq(nrow(...))", anything, "seq_len(nrow(...))")
    ),
    seq_linter()
  )

  expect_lint(
    "c(1:NROW(x), seq(NCOL(y)))",
    list(
      rex::rex("1:NROW(...)", anything, "seq_len(NROW(...)"),
      rex::rex("seq(NCOL(...))", anything, "seq_len(NCOL(...))")
    ),
    seq_linter()
  )
})

test_that("Message recommends rev() correctly", {
  linter <- seq_linter()

  expect_lint(".N:1", rex::rex("Use rev(seq_len(.N))"), linter)
  expect_lint("n():1", rex::rex("Use rev(seq_len(n()))"), linter)
  expect_lint("nrow(x):1", rex::rex("Use rev(seq_len(nrow(...)))"), linter)
  expect_lint("length(x):1", rex::rex("Use rev(seq_along(...))"), linter)
})