test_that("can subset with regexps", {
  x <- c("a", "b", "c")
  expect_equal(str_subset(x, "a|c"), c("a", "c"))
  expect_equal(str_subset(x, "a|c", negate = TRUE), "b")
})

test_that("can subset with fixed patterns", {
  expect_equal(str_subset(c("i", "I"), fixed("i")), "i")
  expect_equal(
    str_subset(c("i", "I"), fixed("i", ignore_case = TRUE)),
    c("i", "I")
  )

  # negation works
  expect_equal(str_subset(c("i", "I"), fixed("i"), negate = TRUE), "I")
})

test_that("str_which is equivalent to grep", {
  expect_equal(
    str_which(head(letters), "[aeiou]"),
    grep("[aeiou]", head(letters))
  )

  # negation works
  expect_equal(
    str_which(head(letters), "[aeiou]", negate = TRUE),
    grep("[aeiou]", head(letters), invert = TRUE)
  )
})

test_that("can use fixed() and coll()", {
  expect_equal(str_subset(c("x", "."), fixed(".")), ".")
  expect_equal(str_subset(c("i", "\u0131"), turkish_I()), "\u0131")
})

test_that("can't use boundaries", {
  expect_snapshot(error = TRUE, {
    str_subset(c("a", "b c"), "")
    str_subset(c("a", "b c"), boundary())
  })
})