test_that("read_lines works on empty files", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw(""), tmp)

  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp), character())
  expect_equal(read_lines(tmp, 1), character())
})

test_that("read_lines works files with no newlines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("foo"), tmp)

  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp), "foo")
  expect_equal(read_lines(tmp, 1), "foo")
})

test_that("read_lines works files with only newlines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("\n"), tmp)

  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), "")
  expect_equal(read_lines(tmp), "")
})

test_that("read_lines works files with only windows newlines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("\r\n"), tmp)

  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), "")
  expect_equal(read_lines(tmp), "")
})

test_that("read_lines works with unix line endings", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("foo\nbar\nbaz\n"), tmp)

  expect_equal(read_lines(tmp), c("foo", "bar", "baz"))
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), c("foo"))
})

test_that("read_lines works with unix line endings and no trailing newline", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("foo\nbar\nbaz"), tmp)

  expect_equal(read_lines(tmp), c("foo", "bar", "baz"))
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), c("foo"))
})

test_that("read_lines works with Windows line endings", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("foo\r\nbar\r\nbaz\r\n"), tmp)

  expect_equal(read_lines(tmp), c("foo", "bar", "baz"))
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), c("foo"))
})

test_that("read_lines works with Windows line endings and no trailing newline", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  writeBin(charToRaw("foo\r\nbar\r\nbaz"), tmp)

  expect_equal(read_lines(tmp), c("foo", "bar", "baz"))
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), c("foo"))
})

test_that("read_lines works with long lines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  data <- c(
    paste(rep("a", 1024), collapse = ""),
    paste(rep("b", 2048), collapse = "")
  )

  writeLines(data, tmp)

  expect_equal(read_lines(tmp), data)
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), data[[1]])
})

test_that("read_lines works with lots of lines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  data <- rep("a", 1025)

  writeLines(data, tmp)

  expect_equal(read_lines(tmp), data)
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), data[[1]])
})


test_that("read_lines works with really long lines", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  data <- rep(paste(rep("a", 1024 * 1024 - 2), collapse = ""), 5)

  con <- file(tmp, "wb")
  base::writeLines(data, con, sep = "\r\n")
  close(con)

  expect_equal(read_lines(tmp), data)
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), data[[1]])
})

test_that("read_lines works with lots of lines that don't end with a newline", {
  tmp <- tempfile()
  on.exit(unlink(tmp))

  data <- rep("a", 1025)

  writeBin(paste(data, collapse = "\n"), tmp)

  expect_equal(read_lines(tmp), data)
  expect_equal(read_lines(tmp, 0), character())
  expect_equal(read_lines(tmp, 1), "a")
})