1 files changed, 75 insertions, 0 deletions
diff --git a/internal/casino/hardening_casino_rng_test.go b/internal/casino/hardening_casino_rng_test.go
new file mode 100644
index 0000000..2d44441
--- /dev/null
+++ b/internal/casino/hardening_casino_rng_test.go
@@ -0,0 +1,75 @@
+package casino
+
+import "testing"
+
+// RNG seams: outcomes must not be replayable from a clock, while tests keep
+// a deterministic, injectable seed.
+
+func TestNewManagerSeedIsADeterministicSeam(t *testing.T) {
+	cfg := MachineConfig{ID: "slots", Game: GameSlots}
+	same := []*Machine{
+		NewManager(7).EnsureMachine(1, cfg),
+		NewManager(7).EnsureMachine(1, cfg),
+	}
+	other := NewManager(8).EnsureMachine(1, cfg)
+
+	first := machineDraws(same[0])
+	if got := machineDraws(same[1]); !sameDraws(first, got) {
+		t.Fatalf("the same seed produced different slot streams: %v vs %v", first, got)
+	}
+	if got := machineDraws(other); sameDraws(first, got) {
+		t.Fatalf("different seeds produced the same slot stream: %v", got)
+	}
+}
+
+func TestNewManagerEntropySeedsFromCryptoRand(t *testing.T) {
+	if seed := entropySeed(); seed < 0 {
+		t.Fatalf("entropy seed %d is negative", seed)
+	}
+	seen := make(map[int64]bool)
+	for i := 0; i < 4; i++ {
+		m := NewManagerEntropy()
+		if m.seed < 0 {
+			t.Fatalf("NewManagerEntropy seed %d is negative", m.seed)
+		}
+		seen[m.seed] = true
+	}
+	if len(seen) < 2 {
+		t.Fatalf("NewManagerEntropy reused one seed across %d managers", len(seen))
+	}
+}
+
+// Each game gets its own stream seeded from the manager's: no two tables or
+// machines may share reel results.
+func TestManagerGamesKeepIndependentStreams(t *testing.T) {
+	m := NewManager(3)
+	first := m.EnsureMachine(1, MachineConfig{ID: "slots_a", Game: GameSlots})
+	second := m.EnsureMachine(1, MachineConfig{ID: "slots_b", Game: GameSlots})
+	if first == nil || second == nil {
+		t.Fatal("machines were not created")
+	}
+	if sameDraws(machineDraws(first), machineDraws(second)) {
+		t.Fatal("two machines share one RNG stream")
+	}
+}
+
+// machineDraws consumes n values from a game's own stream.
+func machineDraws(m *Machine) []int64 {
+	draws := make([]int64, 8)
+	for i := range draws {
+		draws[i] = m.rng.Int63()
+	}
+	return draws
+}
+
+func sameDraws(a, b []int64) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}