test(chain): pin HTLC expiration boundary

Co-Authored-By: Charon <charon@lethean.io>

chain/ring.go

@@ -53,7 +53,8 @@ func (c *Chain) GetRingOutputs(height, amount uint64, offsets []uint64) ([]types
 // TxOutMultisig does not carry enough context here to select the exact spend
 // path, so we return the first listed key as a deterministic fallback.
 // TxOutHTLC selects redeem vs refund based on whether the spending height is
-// before or after the contract expiration.
+// before or after the contract expiration. The refund path only opens after
+// the expiration height has passed.
 func ringOutputSpendKey(height uint64, target types.TxOutTarget) (types.PublicKey, error) {
 	if t, ok := types.AsTxOutToKey(target); ok {
 		return t.Key, nil

chain/ring_test.go

@@ -142,6 +142,47 @@ func TestGetRingOutputs_Good_HTLC(t *testing.T) {
 	}
 }
 
+func TestGetRingOutputs_Good_HTLCExpirationBoundary(t *testing.T) {
+	c := newTestChain(t)
+
+	redeem := types.PublicKey{0xAA, 0xBB, 0xCC}
+	refund := types.PublicKey{0xDD, 0xEE, 0xFF}
+	tx := types.Transaction{
+		Version: types.VersionPreHF4,
+		Vin:     []types.TxInput{types.TxInputGenesis{Height: 0}},
+		Vout: []types.TxOutput{
+			types.TxOutputBare{
+				Amount: 1000,
+				Target: types.TxOutHTLC{
+					HTLCHash:   types.Hash{0x01},
+					Flags:      0,
+					Expiration: 200,
+					PKRedeem:   redeem,
+					PKRefund:   refund,
+				},
+			},
+		},
+		Extra:      wire.EncodeVarint(0),
+		Attachment: wire.EncodeVarint(0),
+	}
+	txHash := wire.TransactionHash(&tx)
+
+	if err := c.PutTransaction(txHash, &tx, &TxMeta{KeeperBlock: 0, GlobalOutputIndexes: []uint64{0}}); err != nil {
+		t.Fatalf("PutTransaction: %v", err)
+	}
+	if _, err := c.PutOutput(1000, txHash, 0); err != nil {
+		t.Fatalf("PutOutput: %v", err)
+	}
+
+	pubs, err := c.GetRingOutputs(200, 1000, []uint64{0})
+	if err != nil {
+		t.Fatalf("GetRingOutputs boundary path: %v", err)
+	}
+	if pubs[0] != redeem {
+		t.Errorf("pubs[0] boundary path: got %x, want %x", pubs[0], redeem)
+	}
+}
+
 func TestGetRingOutputs_Good_MultipleOutputs(t *testing.T) {
 	c := newTestChain(t)