Add polygon tests, fix area() function

Author: joto

src/geom-functions.cpp

@@ -301,7 +301,7 @@ double area(geometry_t const &geom)
         }
     }
 
-    return total;
+    return std::abs(total);
 }
 
 namespace {

tests/CMakeLists.txt

@@ -46,6 +46,7 @@ set_test(test-geom-box LABELS NoDB)
 set_test(test-geom-lines LABELS NoDB)
 set_test(test-geom-null LABELS NoDB)
 set_test(test-geom-points LABELS NoDB)
+set_test(test-geom-polygons LABELS NoDB)
 set_test(test-middle)
 set_test(test-node-locations LABELS NoDB)
 set_test(test-options-database LABELS NoDB)

tests/test-geom-polygons.cpp

@@ -0,0 +1,65 @@
+/**
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This file is part of osm2pgsql (https://osm2pgsql.org/).
+ *
+ * Copyright (C) 2006-2022 by the osm2pgsql developer community.
+ * For a full list of authors see the git log.
+ */
+
+#include <catch.hpp>
+
+#include "geom-functions.hpp"
+#include "geom.hpp"
+
+TEST_CASE("polygon geometry without inner", "[NoDB]")
+{
+    geom::geometry_t const geom{
+        geom::polygon_t{geom::ring_t{{0, 0}, {0, 1}, {1, 1}, {1, 0}, {0, 0}}}};
+
+    REQUIRE(num_geometries(geom) == 1);
+    REQUIRE(area(geom) == Approx(1.0));
+    REQUIRE(geometry_type(geom) == "POLYGON");
+    REQUIRE(centroid(geom) == geom::geometry_t{geom::point_t{0.5, 0.5}});
+}
+
+TEST_CASE("polygon geometry without inner (reverse)", "[NoDB]")
+{
+    geom::geometry_t const geom{
+        geom::polygon_t{geom::ring_t{{0, 0}, {1, 0}, {1, 1}, {0, 1}, {0, 0}}}};
+
+    REQUIRE(num_geometries(geom) == 1);
+    REQUIRE(area(geom) == Approx(1.0));
+    REQUIRE(geometry_type(geom) == "POLYGON");
+    REQUIRE(centroid(geom) == geom::geometry_t{geom::point_t{0.5, 0.5}});
+}
+
+TEST_CASE("polygon geometry with inner", "[NoDB]")
+{
+    geom::geometry_t const geom{
+        geom::polygon_t{geom::ring_t{{0, 0}, {0, 1}, {1, 1}, {1, 0}, {0, 0}}}};
+
+    REQUIRE(num_geometries(geom) == 1);
+    REQUIRE(area(geom) == Approx(1.0));
+    REQUIRE(geometry_type(geom) == "POLYGON");
+    REQUIRE(centroid(geom) == geom::geometry_t{geom::point_t{0.5, 0.5}});
+}
+
+TEST_CASE("geom::polygon_t", "[NoDB]")
+{
+    geom::polygon_t polygon;
+
+    REQUIRE(polygon.outer().empty());
+    polygon.outer() = geom::ring_t{{0, 0}, {0, 3}, {3, 3}, {3, 0}, {0, 0}};
+    polygon.inners().emplace_back(
+        geom::ring_t{{1, 1}, {2, 1}, {2, 2}, {1, 2}, {1, 1}});
+
+    REQUIRE(polygon.num_geometries() == 1);
+    REQUIRE(polygon.inners().size() == 1);
+
+    geom::geometry_t geom{std::move(polygon)};
+    REQUIRE(num_geometries(geom) == 1);
+    REQUIRE(area(geom) == Approx(8.0));
+    REQUIRE(geometry_type(geom) == "POLYGON");
+    REQUIRE(centroid(geom) == geom::geometry_t{geom::point_t{1.5, 1.5}});
+}