81 lines
2.7 KiB
Elixir
81 lines
2.7 KiB
Elixir
defmodule Microwaveprop.Rover.ElevationTest do
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use ExUnit.Case, async: false
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alias Microwaveprop.Rover.Elevation
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setup do
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tmp = Path.join(System.tmp_dir!(), "rover_elev_#{System.unique_integer([:positive])}")
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File.mkdir_p!(tmp)
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prev = Application.get_env(:microwaveprop, :srtm_tiles_dir)
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Application.put_env(:microwaveprop, :srtm_tiles_dir, tmp)
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on_exit(fn ->
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File.rm_rf(tmp)
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if prev do
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Application.put_env(:microwaveprop, :srtm_tiles_dir, prev)
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else
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Application.delete_env(:microwaveprop, :srtm_tiles_dir)
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end
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end)
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:ok
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end
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describe "lookup_many/1" do
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test "returns map keyed by {lat, lon}, nil values when no tiles available" do
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points = [{33.0, -96.0}, {30.0, -97.0}]
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result = Elevation.lookup_many(points)
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assert is_map(result)
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assert Map.has_key?(result, {33.0, -96.0})
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assert Map.has_key?(result, {30.0, -97.0})
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assert result[{33.0, -96.0}] == nil
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assert result[{30.0, -97.0}] == nil
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end
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test "empty list returns empty map" do
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assert Elevation.lookup_many([]) == %{}
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end
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test "duplicate points are deduplicated before lookup" do
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points = [{33.0, -96.0}, {33.0, -96.0}, {33.1, -97.0}]
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result = Elevation.lookup_many(points)
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assert map_size(result) == 2
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end
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test "points on different tiles each get an entry" do
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points = [{45.0, -120.0}, {30.0, -90.0}]
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result = Elevation.lookup_many(points)
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assert map_size(result) == 2
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assert result[{45.0, -120.0}] == nil
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assert result[{30.0, -90.0}] == nil
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end
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test "reads elevation from a valid SRTM tile file" do
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# SRTM tile at lat~0, lon~0 (tile N00E000.hgt) stores 3601×3601
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# 16-bit big-endian signed integers. Write a minimal valid tile
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# with known elevation at the first sample point.
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tile_path = Path.join(Application.get_env(:microwaveprop, :srtm_tiles_dir), "N00E000.hgt")
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elev_value = 1234
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# Build enough binary to cover offset 0 (row=0, col=0 = first sample)
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binary = <<elev_value::signed-big-integer-size(16)>>
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File.write!(tile_path, binary)
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# lat=0.9999, lon=0.0 → row=0, col=0 → offset=0
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result = Elevation.lookup_many([{0.9999, 0.0}])
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assert result[{0.9999, 0.0}] == elev_value
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end
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test "returns nil for SRTM void sentinel values (-32768)" do
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tile_path = Path.join(Application.get_env(:microwaveprop, :srtm_tiles_dir), "N00E000.hgt")
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# SRTM void sentinel is -32768
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File.write!(tile_path, <<-32_768::signed-big-integer-size(16)>>)
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result = Elevation.lookup_many([{0.9999, 0.0}])
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assert result[{0.9999, 0.0}] == nil
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end
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end
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end
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