Mapgen: Add rudimentary unittests

src/unittest/test_mapgen.cpp

@@ -0,0 +1,114 @@
+// Luanti
+// SPDX-License-Identifier: LGPL-2.1-or-later
+// Copyright (C) 2024 Minetest core developers & community
+
+#include "test.h"
+
+#include "emerge.h"
+#include "mapgen/mapgen.h"
+#include "mapgen/mg_biome.h"
+#include "mock_server.h"
+
+class TestMapgen : public TestBase
+{
+public:
+	TestMapgen() { TestManager::registerTestModule(this); }
+	const char *getName() { return "TestMapgen"; }
+
+	void runTests(IGameDef *gamedef);
+
+	void testBiomeGen(IGameDef *gamedef);
+};
+
+static TestMapgen g_test_instance;
+
+namespace {
+	class MockBiomeManager : public BiomeManager {
+	public:
+		MockBiomeManager(Server *server) : BiomeManager(server) {}
+
+		void setNodeDefManager(const NodeDefManager *ndef)
+		{
+			m_ndef = ndef;
+		}
+	};
+}
+
+void TestMapgen::runTests(IGameDef *gamedef)
+{
+	TEST(testBiomeGen, gamedef);
+}
+
+void TestMapgen::testBiomeGen(IGameDef *gamedef)
+{
+	MockServer server(getTestTempDirectory());
+	MockBiomeManager bmgr(&server);
+	bmgr.setNodeDefManager(gamedef->getNodeDefManager());
+
+	{
+		// Add some biomes (equivalent to l_register_biome)
+		// Taken from minetest_game/mods/default/mapgen.lua
+		size_t bmgr_count = bmgr.getNumObjects(); // this is 1 ?
+
+		Biome *b = BiomeManager::create(BIOMETYPE_NORMAL);
+		b->name = "deciduous_forest";
+		b->c_top = t_CONTENT_GRASS;
+		b->depth_top = 1;
+		b->c_filler = t_CONTENT_BRICK; // dirt
+		b->depth_filler = 3;
+		b->c_stone = t_CONTENT_STONE;
+		b->min_pos.Y = 1;
+		b->heat_point = 60.0f;
+		b->humidity_point = 68.0f;
+		UASSERT(bmgr.add(b) != OBJDEF_INVALID_HANDLE);
+
+		b = BiomeManager::create(BIOMETYPE_NORMAL);
+		b->name = "deciduous_forest_shore";
+		b->c_top = t_CONTENT_BRICK; // dirt
+		b->depth_top = 1;
+		b->c_filler = t_CONTENT_BRICK; // dirt
+		b->depth_filler = 3;
+		b->c_stone = t_CONTENT_STONE;
+		b->max_pos.Y = 0;
+		b->heat_point = 60.0f;
+		b->humidity_point = 68.0f;
+		UASSERT(bmgr.add(b) != OBJDEF_INVALID_HANDLE);
+		UASSERT(bmgr.getNumObjects() - bmgr_count == 2);
+	}
+
+
+	std::unique_ptr<BiomeParams> params(BiomeManager::createBiomeParams(BIOMEGEN_ORIGINAL));
+
+	constexpr v3s16 CSIZE(16, 16, 16); // misleading name. measured in nodes.
+	std::unique_ptr<BiomeGen> biomegen(
+		bmgr.createBiomeGen(BIOMEGEN_ORIGINAL, params.get(), CSIZE)
+	);
+
+	{
+		// Test biome transitions
+		//   getBiomeAtIndex (Y only)
+		//   getNextTransitionY
+		const struct {
+			s16 check_y;
+			const char *name;
+			s16 next_y;
+		} expected_biomes[] = {
+			{ MAX_MAP_GENERATION_LIMIT, "deciduous_forest", 1 },
+			// ^ FIXME: next_y should be 0 (min_pos.Y - 1)
+			{ 1, "deciduous_forest", 0 },
+			{ 0, "deciduous_forest_shore", -MAX_MAP_GENERATION_LIMIT },
+			{ -100, "deciduous_forest_shore", -MAX_MAP_GENERATION_LIMIT },
+		};
+		for (const auto expected : expected_biomes) {
+			Biome *biome = biomegen->getBiomeAtIndex(
+				(1 * CSIZE.X) + 1, // index in CSIZE 2D noise map
+				v3s16(2000, expected.check_y, -1000) // absolute coordinates
+			);
+			s16 next_y = biomegen->getNextTransitionY(expected.check_y);
+
+			UASSERTEQ(auto, biome->name, expected.name);
+			UASSERTEQ(auto, next_y, expected.next_y);
+		}
+	}
+}
+