[core] Don't earcut more than 500 inner rings

test/tile/geometry_tile.cpp

@@ -0,0 +1,61 @@
+#include <mbgl/test/util.hpp>
+#include <mbgl/tile/geometry_tile.hpp>
+
+using namespace mbgl;
+
+TEST(GeometryTile, classifyRings1) {
+    std::vector<GeometryCollection> polygons = classifyRings({
+      { {0, 0}, {0, 40}, {40, 40}, {40, 0}, {0, 0} }
+    });
+
+    // output: 1 polygon
+    ASSERT_EQ(polygons.size(), 1);
+    // output: polygon 1 has 1 exterior
+    ASSERT_EQ(polygons[0].size(), 1);
+}
+
+TEST(GeometryTile, classifyRings2) {
+    std::vector<GeometryCollection> polygons = classifyRings({
+      { {0, 0}, {0, 40}, {40, 40}, {40, 0}, {0, 0} },
+      { {10, 10}, {20, 10}, {20, 20}, {10, 10} }
+    });
+
+    // output: 1 polygon
+    ASSERT_EQ(polygons.size(), 1);
+    // output: polygon 1 has 1 exterior, 1 interior
+    ASSERT_EQ(polygons[0].size(), 2);
+}
+
+TEST(GeometryTile, limitHoles1) {
+    GeometryCollection polygon = {
+      { {0, 0}, {0, 40}, {40, 40}, {40, 0}, {0, 0} },
+      { {30, 30}, {32, 30}, {32, 32}, {30, 30} },
+      { {10, 10}, {20, 10}, {20, 20}, {10, 10} }
+    };
+
+    limitHoles(polygon, 1);
+
+    // output: polygon 1 has 1 exterior, 1 interior
+    ASSERT_EQ(polygon.size(), 2);
+
+    // ensure we've kept the right rings (ones with largest areas)
+    ASSERT_EQ(polygon[0][0].x, 0);
+    ASSERT_EQ(polygon[1][0].x, 10);
+}
+
+TEST(GeometryTile, limitHoles2) {
+    GeometryCollection polygon = {
+      { {0, 0}, {0, 40}, {40, 40}, {40, 0}, {0, 0} },
+      { {10, 10}, {20, 10}, {20, 20}, {10, 10} },
+      { {30, 30}, {32, 30}, {32, 32}, {30, 30} }
+    };
+
+    limitHoles(polygon, 1);
+
+    // output: polygon 1 has 1 exterior, 1 interior
+    ASSERT_EQ(polygon.size(), 2);
+
+    // ensure we've kept the right rings (ones with largest areas)
+    ASSERT_EQ(polygon[0][0].x, 0);
+    ASSERT_EQ(polygon[1][0].x, 10);
+}