test_that("apply_threshold() and convert_regions_to_grid() works", {
  proxies <- load_proxies_belgium()

  # CONVERT regions TO GRID
  units <- flexurba::units_belgium
  expect_equal(
    length(unique(terra::values(convert_regions_to_grid(units, proxies$pop)))),
    580
  )
  
  expect_equal(
    length(unique(terra::values(convert_regions_to_grid(
      units,
      proxies$pop,
      "GID_2"
    )))),
    12
  )
  
  expect_error(convert_regions_to_grid("wrongpath.geojson", proxies$pop))
  expect_error(convert_regions_to_grid(TRUE, proxies$pop))
  expect_error(convert_regions_to_grid(units, proxies$pop, "wrongid"))

  # PREDEFINED - ABSOLUTE
  pop_above_1500 <- apply_threshold(
    proxies$pop,
    type = "predefined",
    threshold_value = 1500
  )
  expect_equal(
    sum(terra::values(pop_above_1500$rboundaries), na.rm = TRUE),
    3920
  )

  built_above_20 <- apply_threshold(
    proxies$built,
    type = "predefined",
    threshold_value = 0.20
  )
  expect_equal(
    sum(terra::values(built_above_20$rboundaries), na.rm = TRUE),
    3573
  )

  light_above_30 <- apply_threshold(
    proxies$light,
    type = "predefined",
    threshold_value = 30
  )
  expect_equal(
    sum(terra::values(light_above_30$rboundaries), na.rm = TRUE),
    1079
  )

  # DATA-DRIVEN - ABSOLUTE
  pop_above_p95 <- apply_threshold(
    proxies$pop,
    type = "data-driven",
    fun = "p95"
  )
  expect_equal(
    sum(terra::values(pop_above_p95$rboundaries), na.rm = TRUE),
    3620
  )

  built_above_mean <- apply_threshold(
    proxies$built,
    type = "data-driven",
    fun = "mean"
  )
  expect_equal(
    sum(terra::values(built_above_mean$rboundaries), na.rm = TRUE),
    23728
  )

  light_above_p75 <- apply_threshold(
    proxies$light,
    type = "data-driven",
    fun = "p75"
  )
  expect_equal(
    sum(terra::values(light_above_p75$rboundaries), na.rm = TRUE),
    18304
  )

  # PREDEFINED - RELATIVE
  regions <- convert_regions_to_grid(
    flexurba::units_belgium,
    proxies$pop,
    "GID_1"
  )
  withregions1 <- apply_threshold(
    proxies$pop,
    type = "predefined",
    threshold_value = 1500,
    regions = regions
  )
  expect_equal(sum(terra::values(withregions1$rboundaries), na.rm = TRUE), 2052)
  expect_equal(withregions1$threshold$threshold_value, c(1500, 1500, 1500))

  withregions2 <- apply_threshold(
    proxies$pop,
    type = "predefined",
    threshold_value = c(1500, 1200, 1000),
    regions = regions
  )
  expect_equal(sum(terra::values(withregions2$rboundaries), na.rm = TRUE), 2231)
  expect_equal(withregions2$threshold$threshold_value, c(1500, 1200, 1000))

  # DATA-DRIVEN - RELATIVE
  withregions3 <- apply_threshold(
    proxies$pop,
    type = "data-driven",
    fun = "p95",
    regions = flexurba::units_belgium
  )
  expect_equal(sum(terra::values(withregions3$rboundaries), na.rm = TRUE), 1780)

  province_regions <- convert_regions_to_grid(
    flexurba::units_belgium,
    proxies$pop,
    "GID_2"
  )
  withregions5 <- apply_threshold(
    proxies$pop,
    type = "data-driven",
    fun = "p95",
    regions = province_regions
  )
  expect_equal(sum(terra::values(withregions5$rboundaries), na.rm = TRUE), 1676)

  # INCORRECT ARGUMENTS
  expect_error(apply_threshold(
    proxies$pop,
    type = "data-driven",
    threshold_value = 1500
  ))
  expect_error(apply_threshold(proxies$pop, type = "predefined", fun = "max"))
  expect_warning(apply_threshold(
    proxies$pop,
    type = "data-driven",
    fun = "mean",
    threshold_value = 1500
  ))
  expect_warning(apply_threshold(
    proxies$pop,
    type = "predefined",
    threshold_value = 1500,
    fun = "max"
  ))

  expect_error(apply_threshold(proxies$pop, type = "data-driven", fun = "p101"))
  expect_error(apply_threshold(proxies$pop, type = "data-driven", fun = "iets"))
  expect_error(apply_threshold(proxies$pop, type = "data-driven", fun = "p0.5"))
  expect_error(apply_threshold(
    proxies$pop,
    type = "data-driven",
    fun = terra::mask
  ))

  # WARNING WHEN MORE THAN ONE LAYER
  terra::add(proxies$pop) <- proxies$built
  expect_warning(apply_threshold(
    proxies$pop,
    type = "predefined",
    threshold_value = 3
  ))
})