Graham McIntire
cb2937f12c
34 characterization tests for pure/wrapper modules. Documents existing behavior — no production code changes.
98 lines
3.2 KiB
Elixir
98 lines
3.2 KiB
Elixir
defmodule Microwaveprop.GeoTest do
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use ExUnit.Case, async: true
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alias Microwaveprop.Geo
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alias Microwaveprop.Radio.Maidenhead
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describe "haversine_km/4" do
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test "returns 0.0 for identical points" do
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assert Geo.haversine_km(32.9, -96.8, 32.9, -96.8) == 0.0
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end
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test "matches a known long-distance pair (DFW to Newington, CT)" do
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assert_in_delta Geo.haversine_km(32.9, -96.8, 41.714, -72.727), 2333.3, 1.0
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end
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test "computes a half-circumference for antipodal equator points" do
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# Half the Earth's circumference at R = 6371 km is ~20015 km.
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assert_in_delta Geo.haversine_km(0.0, 0.0, 0.0, 180.0), 20_015.0, 1.0
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end
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test "is symmetric in its arguments" do
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forward = Geo.haversine_km(32.9, -96.8, 41.714, -72.727)
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reverse = Geo.haversine_km(41.714, -72.727, 32.9, -96.8)
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assert_in_delta forward, reverse, 0.0001
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end
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test "one degree of latitude is roughly 111 km" do
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assert_in_delta Geo.haversine_km(32.0, -96.0, 33.0, -96.0), 111.195, 0.1
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end
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end
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describe "bearing_deg/4" do
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test "returns 0.0 for due north" do
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assert Geo.bearing_deg(32.0, -96.0, 33.0, -96.0) == 0.0
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end
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test "returns ~90 for due east at the equator" do
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assert_in_delta Geo.bearing_deg(0.0, 0.0, 0.0, 1.0), 90.0, 0.1
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end
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test "returns 180.0 for due south" do
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assert Geo.bearing_deg(32.0, -96.0, 31.0, -96.0) == 180.0
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end
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test "returns a bearing in the range [0, 360)" do
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bearing = Geo.bearing_deg(32.0, -96.0, 32.0, -97.0)
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assert bearing >= 0.0 and bearing < 360.0
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assert_in_delta bearing, 270.0, 1.0
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end
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test "rounds to one decimal place" do
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# DFW to Newington - pick any pair, the result must have at most 1 decimal.
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bearing = Geo.bearing_deg(32.9, -96.8, 41.714, -72.727)
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assert Float.round(bearing, 1) == bearing
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end
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end
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describe "maidenhead_center/1" do
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test "returns the center of a 4-character grid" do
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# EM12 is lat 32-33, lon -98 to -96, center (32.5, -97.0).
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assert Geo.maidenhead_center("EM12") == {32.5, -97.0}
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end
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test "returns the center of a 6-character grid at higher precision" do
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{lat, lon} = Geo.maidenhead_center("EM12kp")
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assert_in_delta lat, 32.6458, 0.001
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assert_in_delta lon, -97.125, 0.001
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end
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test "accepts lowercase grids" do
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assert Geo.maidenhead_center("em12") == {32.5, -97.0}
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end
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test "returns nil for invalid grid characters" do
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assert Geo.maidenhead_center("ZZZZ") == nil
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end
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end
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describe "latlon_to_grid4/2" do
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test "encodes the DFW area as EM12" do
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assert Geo.latlon_to_grid4(32.9, -96.8) == "EM12"
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end
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test "encodes Newington, CT as FN31" do
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assert Geo.latlon_to_grid4(41.714, -72.727) == "FN31"
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end
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test "encodes the prime-meridian/equator origin as JJ00" do
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assert Geo.latlon_to_grid4(0.0, 0.0) == "JJ00"
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end
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test "agrees with Maidenhead.from_latlon/3 at precision 4 for typical US coords" do
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for {lat, lon} <- [{32.9, -96.8}, {41.714, -72.727}, {40.0, -105.0}, {47.6, -122.3}] do
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assert Geo.latlon_to_grid4(lat, lon) == Maidenhead.from_latlon(lat, lon, 4)
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end
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end
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end
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end
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