Adds tests for new polygons module

tests/test_polygons.py

@@ -0,0 +1,95 @@
+# (C) Copyright 2024 ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+# In applying this licence, ECMWF does not waive the privileges and immunities
+# granted to it by virtue of its status as an intergovernmental organisation
+# nor does it submit to any jurisdiction.
+#
+
+
+import pytest
+from shapely.geometry import MultiPolygon, Polygon
+
+from earthkit.geo.polygons import (
+    _closest_resolution,
+    country_polygons,
+    multipolygon_to_coordinates,
+)
+
+
+@pytest.mark.parametrize(
+    "distance_m, expected_resolution",
+    [
+        (0, "10m"),  # Closest to 10m
+        (20e6, "10m"),  # Closest to 10m
+        (80e6, "110m"),  # Closest to 110m
+        (79e6, "50m"),  # Closest to 50m
+        (45e6, "50m"),  # Closest to 50m
+        (110e6, "110m"),  # Exactly 110m
+    ],
+)
+def test_closest_resolution(distance_m, expected_resolution):
+    assert _closest_resolution(distance_m) == expected_resolution
+
+
+def test_multipolygon_to_coordinates():
+    poly1 = Polygon([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
+    poly2 = Polygon([(2, 2), (3, 2), (3, 3), (2, 3), (2, 2)])
+    multipolygon = MultiPolygon([poly1, poly2])
+
+    coordinates = multipolygon_to_coordinates(multipolygon)
+
+    expected_coordinates = [
+        [[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]],
+        [[2, 2], [2, 3], [3, 3], [3, 2], [2, 2]],
+    ]
+
+    assert coordinates == expected_coordinates
+
+
+def test_country_polygons_invalid_country():
+    with pytest.raises(ValueError):
+        country_polygons("InvalidCountryName")
+
+
+def test_country_polygons_single_country():
+    coordinates = country_polygons("France")
+
+    # Verify the output format
+    assert isinstance(coordinates, list)
+    assert all(isinstance(polygon, list) for polygon in coordinates)
+    assert all(
+        isinstance(coord, list) and len(coord) == 2
+        for polygon in coordinates
+        for coord in polygon
+    )
+
+
+def test_country_polygons_multiple_countries():
+    coordinates = country_polygons(["Poland", "Germany"])
+
+    # Verify the output format
+    assert isinstance(coordinates, list)
+    assert all(isinstance(polygon, list) for polygon in coordinates)
+    assert all(
+        isinstance(coord, list) and len(coord) == 2
+        for polygon in coordinates
+        for coord in polygon
+    )
+
+
+def test_country_polygons_output_format():
+    poly = Polygon([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
+    multipolygon = MultiPolygon([poly])
+
+    coordinates = multipolygon_to_coordinates(multipolygon)
+
+    # Verify the output format
+    assert isinstance(coordinates, list)
+    assert all(isinstance(polygon, list) for polygon in coordinates)
+    assert all(
+        isinstance(coord, list) and len(coord) == 2
+        for polygon in coordinates
+        for coord in polygon
+    )