test_that("horizontal and vertical units are resolved separately", {
  horizontal <- display_unit_info(sf::st_crs(2277))
  expect_false(horizontal$known)
  expect_match(horizontal$note, "source Z: unknown", fixed = TRUE)
  mixed <- display_unit_info(sf::st_crs("EPSG:26917+6360"))
  expect_true(mixed$known)
  expect_equal(mixed$factors, c(1, 1, 1200/3937), tolerance=1e-12)
  metres <- display_unit_info(sf::st_crs("EPSG:26917+5703"))
  expect_equal(metres$factors, c(1,1,1))
  expect_true(metres$known)
})

test_that("international feet and US survey feet keep their distinct factors", {
  p <- data.frame(X=1000, Y=2000, Z=100, Classification=2L, Intensity=400L)
  units <- display_unit_info(sf::st_crs(2277), z_units="ft")
  converted <- scale_display_points(p, units)
  expect_equal(converted$X,1000*1200/3937)
  expect_equal(converted$Z,30.48)
  expect_identical(converted$Classification,p$Classification)
  expect_identical(converted$Intensity,p$Intensity)
  expect_equal(p$Z,100)
  unknown <- display_unit_info(sf::st_crs(NA))
  expect_false(unknown$known)
  expect_equal(scale_display_points(p,unknown),p)
  explicit <- display_unit_info(sf::st_crs(NA),"ft","us-ft")
  expect_true(explicit$known)
  expect_match(explicit$note,"user confirmed",fixed=TRUE)
  expect_false(display_unit_info(sf::st_crs(4326),"m","m")$known)
})

test_that("file previews convert display samples without modifying the original LAS", {
  skip_if_not_installed("lidR")
  p <- data.frame(X=c(3000000,3000010,3000020),Y=c(10000000,10000010,10000020),Z=c(10,20,30))
  las <- lidR::LAS(p)
  sf::st_crs(las) <- sf::st_crs(2277)
  path <- tempfile(fileext=".las"); on.exit(unlink(path))
  lidR::writeLAS(las,path)
  original <- tools::md5sum(path)
  result <- read_preview(path,z_units="ft")
  expect_identical(attr(result,"units"),"m")
  expect_equal(result$Z+attr(result,"origin")[["Z"]],p$Z*.3048,tolerance=1e-6)
  expect_equal(result$X+attr(result,"origin")[["X"]],p$X*1200/3937,tolerance=1e-6)
  expect_identical(tools::md5sum(path),original)
  unknown <- read_forest_preview(path,percent=100)
  expect_match(attr(unknown,"units"),"unverified")
  expect_error(read_forest_preview(path,percent=100,voxel=1),"Confirm horizontal")
  expect_error(read_comparison_cloud(path,sf::st_sf(geometry=sf::st_as_sfc(sf::st_bbox(c(xmin=2999900,ymin=9999900,xmax=3000100,ymax=10000100),crs=2277)))),"known horizontal and elevation units")
  roi <- sf::st_sf(geometry=sf::st_as_sfc(sf::st_bbox(c(xmin=2999900,ymin=9999900,xmax=3000100,ymax=10000100),crs=2277)))
  compared <- read_comparison_cloud(path,roi,z_units="ft")
  expect_equal(compared$points$Z,p$Z*.3048,tolerance=1e-6)
  expect_equal(compared$points$X,p$X*1200/3937,tolerance=1e-6)
  expect_match(compared$units_note,"scaled to metres",fixed=TRUE)
})