Initial commit: RegionIO Minecraft server core (26.1.2/protocol 775)

Vanilla-faithful overworld generator (final_density + multi-noise biomes),
full connection lifecycle (status/login/configuration/play), chunk streaming,
creative block editing, and the protocol/nbt/registry infrastructure.

internal/worldgen/biome_test.go

@@ -0,0 +1,96 @@
+package worldgen
+
+import (
+	"testing"
+)
+
+func TestQuantize(t *testing.T) {
+	cases := []struct {
+		v    float64
+		want int64
+	}{
+		{0.0, 0},
+		{0.5, 5000},
+		{-1.0, -10000},
+		{1.0, 10000},
+		{-0.15, -1500},
+		{0.55, 5500},
+	}
+	for _, c := range cases {
+		if got := quantize(c.v); got != c.want {
+			t.Errorf("quantize(%v) = %d, want %d", c.v, got, c.want)
+		}
+	}
+}
+
+// TestFitDistanceZero confirms identical points are zero-distance and distinct
+// points are positive; the exact value is not asserted to stay robust to
+// representation choices.
+func TestFitDistance(t *testing.T) {
+	a := NewTargetPoint(0, 0, 0, 0, 0, 0)
+	if got := fitDistance(a, a); got != 0 {
+		t.Errorf("fitDistance(a,a) = %d, want 0", got)
+	}
+	b := NewTargetPoint(1, 0, 0, 0, 0, 0)
+	// 10000^2 per axis of difference.
+	if got := fitDistance(a, b); got != 10000*10000 {
+		t.Errorf("fitDistance for 1.0 temp diff = %d, want %d", got, int64(10000*10000))
+	}
+}
+
+// TestRangeContains checks the half-open [min, max) band used by the finder.
+func TestRangeContains(t *testing.T) {
+	r := ClimateRange{Min: 0, Max: 100}
+	if !r.contains(0) {
+		t.Error("min should be inclusive")
+	}
+	if r.contains(100) {
+		t.Error("max should be exclusive")
+	}
+	if !r.contains(50) {
+		t.Error("interior should contain")
+	}
+}
+
+// TestSampleColumnDeterministic verifies the same seed/coords give the same
+// biome and a different seed gives (almost certainly) a different one.
+func TestSampleColumnDeterministic(t *testing.T) {
+	od1, err := LoadOverworldFinalDensity(1)
+	if err != nil {
+		t.Fatalf("load seed 1: %v", err)
+	}
+	od2, err := LoadOverworldFinalDensity(99999)
+	if err != nil {
+		t.Fatalf("load seed 99999: %v", err)
+	}
+
+	p1a := SampleColumn(od1, 63, 100, 200)
+	p1b := SampleColumn(od1, 63, 100, 200)
+	if p1a != p1b {
+		t.Error("same seed/coords should produce identical TargetPoint")
+	}
+
+	p2 := SampleColumn(od2, 63, 100, 200)
+	if p1a == p2 {
+		// Not a hard failure (collisions exist), but flag it for inspection.
+		t.Log("note: different seed produced identical climate point at (100,200)")
+	}
+}
+
+// TestClimateFieldsLoaded confirms the loader populates all six climate axes
+// from the noise_router (regression guard for the loader change).
+func TestClimateFieldsLoaded(t *testing.T) {
+	od, err := LoadOverworldFinalDensity(42)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	if od.Final == nil {
+		t.Fatal("Final density not loaded")
+	}
+	dfs := []DensityFunction{od.Temperature, od.Humidity, od.Continentalness, od.Erosion, od.Weirdness, od.Depth}
+	for i, df := range dfs {
+		if df == nil {
+			t.Errorf("climate axis %d not loaded", i)
+		}
+	}
+}