test: add tests for region-file chunk storage in 32x32 chunk pages

tests/testRegion.cpp

@@ -0,0 +1,89 @@
+#include "testHarness.h"
+#include "vf/Region.h"
+
+using namespace vf;
+
+namespace {
+
+Chunk patternChunk(int seed) {
+    Chunk chunk;
+    for (int x = 0; x < chunkSize; ++x)
+        for (int y = 0; y < chunkSize; ++y)
+            for (int z = 0; z < chunkSize; ++z) {
+                int v = (x + y * 2 + z * 3 + seed) % static_cast<int>(Block::Count);
+                chunk.set(x, y, z, static_cast<Block>(v));
+            }
+    return chunk;
+}
+
+} // namespace
+
+VF_TEST(regionCoordFloorsNegatives) {
+    CHECK(regionForChunk({0, 0, 0}) == (RegionCoord{0, 0}));
+    CHECK(regionForChunk({15, 4, 15}) == (RegionCoord{0, 0}));
+    CHECK(regionForChunk({16, 0, 0}) == (RegionCoord{1, 0}));
+    CHECK(regionForChunk({-1, 0, -1}) == (RegionCoord{-1, -1}));
+    CHECK(regionForChunk({-16, 0, -17}) == (RegionCoord{-1, -2}));
+}
+
+VF_TEST(regionPutGetRoundTrips) {
+    Region region({0, 0});
+    Chunk chunk = patternChunk(7);
+    region.putChunk({1, 2, 3}, chunk);
+    CHECK(region.hasChunk({1, 2, 3}));
+    CHECK(!region.hasChunk({4, 4, 4}));
+
+    Chunk back;
+    CHECK(region.getChunk({1, 2, 3}, back));
+    CHECK(back.raw() == chunk.raw());
+    CHECK(!region.getChunk({9, 9, 9}, back));
+}
+
+VF_TEST(regionSerializeRoundTrips) {
+    Region region({2, -1});
+    Chunk a = patternChunk(1), b = patternChunk(2), c = patternChunk(3);
+    region.putChunk({0, 0, 0}, a);
+    region.putChunk({0, 5, 1}, b);
+    region.putChunk({3, 1, 2}, c);
+
+    std::vector<uint8_t> bytes = region.serialize();
+    Region restored;
+    CHECK(Region::deserialize(bytes.data(), bytes.size(), restored));
+    CHECK(restored.location() == (RegionCoord{2, -1}));
+    CHECK_EQ(restored.chunkCount(), static_cast<std::size_t>(3));
+
+    Chunk out;
+    CHECK(restored.getChunk({0, 5, 1}, out));
+    CHECK(out.raw() == b.raw());
+    CHECK(restored.getChunk({3, 1, 2}, out));
+    CHECK(out.raw() == c.raw());
+}
+
+VF_TEST(regionRejectsBadInput) {
+    Region region({0, 0});
+    region.putChunk({0, 0, 0}, patternChunk(4));
+    std::vector<uint8_t> bytes = region.serialize();
+
+    Region out;
+    bytes[0] ^= 0xff;
+    CHECK(!Region::deserialize(bytes.data(), bytes.size(), out));
+    bytes[0] ^= 0xff;
+    CHECK(!Region::deserialize(bytes.data(), bytes.size() / 2, out));   // truncated
+}
+
+VF_TEST(regionWorldSplitCoversMultipleRegions) {
+    World world;
+    world.setBlock(1, 1, 1, Block::Stone);      // chunk (0,0,0) -> region (0,0)
+    world.setBlock(20 * chunkSize, 0, 0, Block::Grass);   // chunk (20,0,0) -> region (1,0)
+    world.setBlock(-1, 40, -1, Block::Sand);    // chunk (-1,2,-1) -> region (-1,-1)
+
+    auto regions = splitWorldIntoRegions(world);
+    CHECK(regions.size() >= 3);
+
+    std::vector<uint8_t> blob = serializeRegions(world);
+    World restored;
+    CHECK(deserializeRegions(blob.data(), blob.size(), restored));
+    CHECK(restored.blockAt(1, 1, 1) == Block::Stone);
+    CHECK(restored.blockAt(20 * chunkSize, 0, 0) == Block::Grass);
+    CHECK(restored.blockAt(-1, 40, -1) == Block::Sand);
+}