test_that("get_resolution extracts resolution", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 10)
  expect_equal(a5_get_resolution(cell), 10L)
})

test_that("cell_to_parent returns coarser cell", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 10)
  parent <- a5_cell_to_parent(cell)
  expect_equal(a5_get_resolution(parent), 9L)
})

test_that("cell_to_parent with explicit resolution", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 10)
  parent <- a5_cell_to_parent(cell, parent_resolution = 5)
  expect_equal(a5_get_resolution(parent), 5L)
})

test_that("cell_to_children returns 4 children", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 5)
  children <- a5_cell_to_children(cell)
  expect_length(children, 4L)
  expect_true(all(a5_get_resolution(children) == 6L))
})

test_that("get_resolution is vectorised", {
  cells <- a5_lonlat_to_cell(c(0, 10), c(0, 10), resolution = c(3L, 7L))
  expect_equal(a5_get_resolution(cells), c(3L, 7L))
})

test_that("cell_to_parent is vectorised", {
  cells <- a5_lonlat_to_cell(c(0, 10), c(0, 10), resolution = 10)
  parents <- a5_cell_to_parent(cells)
  expect_length(parents, 2L)
  expect_true(all(a5_get_resolution(parents) == 9L))
})

test_that("cell_to_children with explicit resolution", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 5)
  children <- a5_cell_to_children(cell, child_resolution = 7)
  expect_length(children, 16L)
  expect_true(all(a5_get_resolution(children) == 7L))
})

test_that("res0 cells", {
  cells <- a5_get_res0_cells()
  expect_length(cells, 12L)
  expect_true(all(a5_get_resolution(cells) == 0L))
})

test_that("get_num_cells returns positive double", {
  n <- a5_get_num_cells(0)
  expect_type(n, "double")
  expect_equal(n, 12)
})

test_that("get_num_cells increases with resolution", {
  n5 <- a5_get_num_cells(5)
  n10 <- a5_get_num_cells(10)
  expect_true(n10 > n5)
})

# -- NA propagation -----------------------------------------------------------

test_that("get_resolution propagates NA", {
  cells <- a5_cell(c("0800000000000006", NA))
  res <- a5_get_resolution(cells)
  expect_false(is.na(res[1]))
  expect_true(is.na(res[2]))
})

test_that("cell_to_parent propagates NA", {
  cells <- a5_cell(c("0800000000000006", NA))
  parents <- a5_cell_to_parent(cells)
  expect_false(is.na(parents[1]))
  expect_true(is.na(parents[2]))
})

test_that("a5_cell_to_parent rejects a finer resolution", {
  cells <- a5_lonlat_to_cell(c(0, 10), c(0, 10), c(5, 8))
  expect_error(a5_cell_to_parent(cells, 6), "must not be finer than the cell resolution \\(5\\)")
  expect_identical(a5_get_resolution(a5_cell_to_parent(cells, 5)), c(5L, 5L))
  expect_true(is.na(a5_cell_to_parent(a5_cell(NA), 6)))
})

test_that("a5_cell_to_parent at resolution -1 gives the world cell, as in the crate", {
  world <- a5_cell("0000000000000000")
  cells <- a5_lonlat_to_cell(c(0, 10), c(0, 10), c(0, 8))
  expect_identical(a5_cell_to_parent(cells, -1), c(world, world))
  expect_identical(a5_cell_to_parent(cells[1], -1), a5_cell_to_parent(cells[1]))
  expect_error(a5_cell_to_parent(cells, -2), "between -1 and 30")
})

test_that("the old resolution argument still works but warns", {
  cell <- a5_lonlat_to_cell(-3.19, 55.95, 10)
  expect_warning(
    p <- a5_cell_to_parent(cell, resolution = 5),
    "renamed `parent_resolution`", class = "a5R_warning_deprecated"
  )
  expect_identical(p, a5_cell_to_parent(cell, 5))
  expect_warning(
    k <- a5_cell_to_children(cell, resolution = 11),
    "renamed `child_resolution`", class = "a5R_warning_deprecated"
  )
  expect_identical(k, a5_cell_to_children(cell, 11))
})