old_contents: # http://www.openstreetmap.org/relation/1453306
  # area 1.75564e+10
  assert_has_feature(
      4, 3, 5, 'landuse',
      { 'kind': 'national_park', 'id': -1453306, 'tier': 1,
        'min_zoom': 3 })
  assert_has_feature(
      6, 12, 23, 'pois',
      { 'kind': 'national_park', 'id': -1453306, 'tier': 1,
        'min_zoom': 3.74 })
  
  # http://www.openstreetmap.org/relation/921675
  # area 30089300
  assert_has_feature(
      8, 56, 115, 'landuse',
      { 'kind': 'national_park', 'id': -921675, 'tier': 1,
        'min_zoom': 8 })
  assert_no_matching_feature(
      7, 28, 57, 'landuse',
      { 'kind': 'national_park', 'id': -921675 })
  assert_has_feature(
      8, 56, 115, 'pois',
      { 'kind': 'national_park', 'id': -921675, 'tier': 1,
        'min_zoom': 8.33 })
  
  # this is USFS, so demoted to tier 2 :-(
  # http://www.openstreetmap.org/way/34416231
  # area 86685400
  assert_has_feature(
      8, 71, 98, 'landuse',
      { 'kind': 'forest', 'id': 34416231,
        'tier': 2, 'min_zoom': 8 })
  # this one is clipped by the polygon min_zoom, and so appears at the same
  # level.
  #
  # note that the feature _is_ present in the zoom 8 tile, but gets merged
  # with a nearby feature of the same name, so instead we test this at z9.
  assert_has_feature(
      9, 142, 196, 'pois',
      { 'kind': 'forest', 'id': 34416231,
        'tier': 2, 'min_zoom': 8 })
  
new_contents: # http://www.openstreetmap.org/relation/1453306
  # area 1.75564e+10
  assert_has_feature(
      4, 3, 5, 'landuse',
      { 'kind': 'national_park', 'id': -1453306, 'tier': 1,
        'min_zoom': 3 })
  assert_has_feature(
      6, 12, 23, 'pois',
      { 'kind': 'national_park', 'id': -1453306, 'tier': 1,
        'min_zoom': 3.74 })
  
  # http://www.openstreetmap.org/relation/921675
  # area 30089300
  assert_has_feature(
      8, 56, 115, 'landuse',
      { 'kind': 'national_park', 'tier': 1, 'min_zoom': 8 })
  assert_has_feature(
      8, 56, 115, 'pois',
      { 'kind': 'national_park', 'id': -921675, 'tier': 1,
        'min_zoom': 8.33 })
  
  # this is USFS, so demoted to tier 2 :-(
  # http://www.openstreetmap.org/way/34416231
  # area 86685400
  assert_has_feature(
      8, 71, 98, 'landuse',
      { 'kind': 'forest', 'id': 34416231,
        'tier': 2, 'min_zoom': 8 })
  # this one is clipped by the polygon min_zoom, and so appears at the same
  # level.
  #
  # note that the feature _is_ present in the zoom 8 tile, but gets merged
  # with a nearby feature of the same name, so instead we test this at z9.
  assert_has_feature(
      9, 142, 196, 'pois',
      { 'kind': 'forest', 'id': 34416231,
        'tier': 2, 'min_zoom': 8 })
  
subject: Update national_park tests