TST: create test suite for overlay based on wiki example (#533) (#1899)

Co-authored-by: Martin Fleischmann <martin@martinfleischmann.net>

geopandas/tests/test_overlay.py

@@ -14,6 +14,7 @@ from geopandas import _compat
 from geopandas.testing import assert_geodataframe_equal, assert_geoseries_equal
 import pytest
 
+
 DATA = os.path.join(os.path.abspath(os.path.dirname(__file__)), "data", "overlay")
 
 
@@ -795,3 +796,79 @@ def test_no_intersection():
     expected = GeoDataFrame(columns=["foo", "bar", "geometry"])
     result = overlay(gdf1, gdf2, how="intersection")
     assert_geodataframe_equal(result, expected, check_index_type=False)
+
+
+class TestOverlayWikiExample:
+    def setup_method(self):
+        self.layer_a = GeoDataFrame(geometry=[box(0, 2, 6, 6)])
+
+        self.layer_b = GeoDataFrame(geometry=[box(4, 0, 10, 4)])
+
+        self.intersection = GeoDataFrame(geometry=[box(4, 2, 6, 4)])
+
+        self.union = GeoDataFrame(
+            geometry=[
+                box(4, 2, 6, 4),
+                Polygon([(4, 2), (0, 2), (0, 6), (6, 6), (6, 4), (4, 4), (4, 2)]),
+                Polygon([(10, 0), (4, 0), (4, 2), (6, 2), (6, 4), (10, 4), (10, 0)]),
+            ]
+        )
+
+        self.a_difference_b = GeoDataFrame(
+            geometry=[Polygon([(4, 2), (0, 2), (0, 6), (6, 6), (6, 4), (4, 4), (4, 2)])]
+        )
+
+        self.b_difference_a = GeoDataFrame(
+            geometry=[
+                Polygon([(10, 0), (4, 0), (4, 2), (6, 2), (6, 4), (10, 4), (10, 0)])
+            ]
+        )
+
+        self.symmetric_difference = GeoDataFrame(
+            geometry=[
+                Polygon([(4, 2), (0, 2), (0, 6), (6, 6), (6, 4), (4, 4), (4, 2)]),
+                Polygon([(10, 0), (4, 0), (4, 2), (6, 2), (6, 4), (10, 4), (10, 0)]),
+            ]
+        )
+
+        self.a_identity_b = GeoDataFrame(
+            geometry=[
+                box(4, 2, 6, 4),
+                Polygon([(4, 2), (0, 2), (0, 6), (6, 6), (6, 4), (4, 4), (4, 2)]),
+            ]
+        )
+
+        self.b_identity_a = GeoDataFrame(
+            geometry=[
+                box(4, 2, 6, 4),
+                Polygon([(10, 0), (4, 0), (4, 2), (6, 2), (6, 4), (10, 4), (10, 0)]),
+            ]
+        )
+
+    def test_intersection(self):
+        df_result = overlay(self.layer_a, self.layer_b, how="intersection")
+        assert df_result.geom_equals(self.intersection).bool()
+
+    def test_union(self):
+        df_result = overlay(self.layer_a, self.layer_b, how="union")
+        assert_geodataframe_equal(df_result, self.union)
+
+    def test_a_difference_b(self):
+        df_result = overlay(self.layer_a, self.layer_b, how="difference")
+        assert_geodataframe_equal(df_result, self.a_difference_b)
+
+    def test_b_difference_a(self):
+        df_result = overlay(self.layer_b, self.layer_a, how="difference")
+        assert_geodataframe_equal(df_result, self.b_difference_a)
+
+    def test_symmetric_difference(self):
+        df_result = overlay(self.layer_a, self.layer_b, how="symmetric_difference")
+        assert_geodataframe_equal(df_result, self.symmetric_difference)
+
+    def test_a_identity_b(self):
+        df_result = overlay(self.layer_a, self.layer_b, how="identity")
+        assert_geodataframe_equal(df_result, self.a_identity_b)
+
+    def test_b_identity_a(self):
+        df_result = overlay(self.layer_b, self.layer_a, how="identity")
+        assert_geodataframe_equal(df_result, self.b_identity_a)