test_that("tf_where basics work", {
  lin <- 1:2 * tfd(seq(-1, 1, length.out = 11), seq(-1, 1, length.out = 11)) +
    c(0, 0.1)
  expect_equal(
    tf_where(lin, value %inr% c(-1, -0.5)),
    list(c(-1.0, -0.8, -0.6), c(-0.4))
  )
  expect_equal(
    tf_where(lin, value > 0, "first"),
    c(0.2, 0)
  )
  expect_equal(
    tf_where(lin, value < 0, "last"),
    c(-0.2, -0.2)
  )
  expect_equal(
    tf_where(lin, value <= 0, "range"),
    data.frame(begin = -1, end = c(0, -0.2))
  )
  expect_equal(
    tf_where(lin, value < -1.5, "any"),
    c(FALSE, TRUE)
  )
  expect_identical(
    tf_where(lin, value < -1.5, "any"),
    tf_anywhere(lin, value < -1.5)
  )
  expect_equal(
    tf_where(lin, value < -2),
    list(numeric(0), numeric(0))
  )
})