world: replay datapack features across regions

internal/world/geodes_test.go

@@ -0,0 +1,76 @@
+package world
+
+import (
+	"testing"
+
+	"regionio/internal/worldgen"
+)
+
+func TestGeodePlacementIsDeterministicAndLayered(t *testing.T) {
+	set, err := worldgen.LoadFeatureSet()
+	if err != nil {
+		t.Fatal(err)
+	}
+	config, err := set.Geode("minecraft:amethyst_geode")
+	if err != nil {
+		t.Fatal(err)
+	}
+	makeRegion := func() *decorationRegion {
+		chunks := make([]*Chunk, 0, 25)
+		for cx := int32(-2); cx <= 2; cx++ {
+			for cz := int32(-2); cz <= 2; cz++ {
+				chunk := NewChunk(cx, cz, BiomePlains)
+				for y := MinY; y < MinY+WorldHeight; y++ {
+					for x := 0; x < 16; x++ {
+						for z := 0; z < 16; z++ {
+							chunk.setBlockRaw(x, y, z, StateStone)
+						}
+					}
+				}
+				chunks = append(chunks, chunk)
+			}
+		}
+		region, err := newDecorationRegion(chunks)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := region.setSource(0, 0); err != nil {
+			t.Fatal(err)
+		}
+		return region
+	}
+	origin := worldgen.FeaturePosition{X: 8, Y: 0, Z: 8}
+	a, b := makeRegion(), makeRegion()
+	if !a.placeGeode(worldgen.NewWorldgenRandom(42), 12345, origin, config, set) {
+		t.Fatal("geode placement changed no blocks")
+	}
+	if !b.placeGeode(worldgen.NewWorldgenRandom(42), 12345, origin, config, set) {
+		t.Fatal("second geode placement changed no blocks")
+	}
+	counts := map[uint16]int{}
+	for cx := int32(-1); cx <= 1; cx++ {
+		for cz := int32(-1); cz <= 1; cz++ {
+			left := a.chunks[[2]int32{cx, cz}]
+			right := b.chunks[[2]int32{cx, cz}]
+			for y := MinY; y < MinY+WorldHeight; y++ {
+				for x := 0; x < 16; x++ {
+					for z := 0; z < 16; z++ {
+						if left.GetBlock(x, y, z) != right.GetBlock(x, y, z) {
+							t.Fatalf("geodes differ at chunk (%d,%d) block (%d,%d,%d)", cx, cz, x, y, z)
+						}
+						state := left.GetBlock(x, y, z)
+						if state != StateStone {
+							counts[state]++
+						}
+					}
+				}
+			}
+		}
+	}
+	for _, name := range []string{"minecraft:smooth_basalt", "minecraft:calcite", "minecraft:amethyst_block"} {
+		state, ok := nameToStateID(name, nil)
+		if !ok || counts[state] == 0 {
+			t.Fatalf("geode did not place %s: counts=%v", name, counts)
+		}
+	}
+}