-require File.dirname(__FILE__) + '/../test_helper'
-
-class ShortLinkTest < ActiveSupport::TestCase
- ##
- # tests that encoding and decoding are working to within
- # the acceptable quantisation range.
- def test_encode_decode
- cases = Array.new
- 1000.times do
- cases << [ 180.0 * rand - 90.0, 360.0 * rand - 180.0, (18 * rand).to_i ]
- end
-
- cases.each do |lat, lon, zoom|
- lon2, lat2, zoom2 = ShortLink.decode(ShortLink.encode(lon, lat, zoom))
- # zooms should be identical
- assert_equal zoom, zoom2, "Decoding a encoded short link gives different zoom for (#{lat}, #{lon}, #{zoom})."
- # but the location has a quantisation error introduced at roughly
- # one pixel (i.e: zoom + 8). the sqrt(5) is because each position
- # has an extra bit of accuracy in the lat coordinate, due to the
- # smaller range.
- distance = Math.sqrt((lat - lat2) ** 2 + (lon - lon2) ** 2)
- max_distance = 360.0 / (1 << (zoom + 8)) * 0.5 * Math.sqrt(5)
- assert max_distance > distance, "Maximum expected error exceeded: #{max_distance} <= #{distance} for (#{lat}, #{lon}, #{zoom})."
- end
- end
-
- ##
- # test that links are backwards-compatible, so any old links with
- # the deprecated @ characters in them still work properly.
- def test_deprecated_at_sign
- cases = [["~v2juONc--", "@v2juONc--"],
- ["as3I3GpG~-", "as3I3GpG@-"],
- ["D~hV--", "D@hV--"],
- ["CO0O~m8--", "CO0O@m8--"]]
-
- cases.each do |new_code, old_code|
- assert_equal ShortLink.decode(old_code), ShortLink.decode(new_code),
- "old (#{old_code}) and new (#{new_code}) should decode to the same location."
- end
- end
-end