From f97f60d3d461b3d7952a5632658c1da957956e1c Mon Sep 17 00:00:00 2001
From: yyforyongyu <yong2452@gmail.com>
Date: Fri, 23 May 2025 17:04:40 +0800
Subject: [PATCH] lntest+itest: add `testBumpFeeExternalInput`

---
 itest/list_on_test.go    |  4 ++++
 itest/lnd_bump_fee.go    | 44 ++++++++++++++++++++++++++++++++++++++++
 lntest/rpc/wallet_kit.go | 12 +++++++++++
 3 files changed, 60 insertions(+)

diff --git a/itest/list_on_test.go b/itest/list_on_test.go
index 88b7bb395..7263b2451 100644
--- a/itest/list_on_test.go
+++ b/itest/list_on_test.go
@@ -463,6 +463,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "bumpfee",
 		TestFunc: testBumpFee,
 	},
+	{
+		Name:     "bumpfee external input",
+		TestFunc: testBumpFeeExternalInput,
+	},
 	{
 		Name:     "bumpforceclosefee",
 		TestFunc: testBumpForceCloseFee,
diff --git a/itest/lnd_bump_fee.go b/itest/lnd_bump_fee.go
index 3a4d46cc7..3b89e1088 100644
--- a/itest/lnd_bump_fee.go
+++ b/itest/lnd_bump_fee.go
@@ -587,3 +587,47 @@ func runBumpFee(ht *lntest.HarnessTest, alice *node.HarnessNode) {
 	// Clean up the mempool.
 	ht.MineBlocksAndAssertNumTxes(1, 2)
 }
+
+// testBumpFeeExternalInput assert that when the bump fee RPC is called with an
+// outpoint unknown to the node's wallet, an error is returned.
+func testBumpFeeExternalInput(ht *lntest.HarnessTest) {
+	alice := ht.NewNode("Alice", nil)
+	bob := ht.NewNode("Bob", nil)
+
+	// We'll start the test by sending Alice some coins, which she'll use
+	// to send to Bob.
+	ht.FundCoins(btcutil.SatoshiPerBitcoin, alice)
+
+	// Alice sends 0.5 BTC to Bob. This tx should have two outputs - one
+	// that belongs to Bob, the other is Alice's change output.
+	tx := ht.SendCoins(alice, bob, btcutil.SatoshiPerBitcoin/2)
+	txid := tx.TxHash()
+
+	// Find the wrong index to perform the fee bump. We assume the first
+	// output belongs to Bob, and switch to the second if the second output
+	// has a larger output value. Given we've funded Alice 1 btc, she then
+	// sends 0.5 btc to Bob, her change output will be below 0.5 btc after
+	// paying the mining fees.
+	wrongIndex := 0
+	if tx.TxOut[0].Value < tx.TxOut[1].Value {
+		wrongIndex = 1
+	}
+
+	// Alice now tries to bump the wrong output on this tx.
+	op := &lnrpc.OutPoint{
+		TxidBytes:   txid[:],
+		OutputIndex: uint32(wrongIndex),
+	}
+
+	// Create a request with the wrong outpoint.
+	bumpFeeReq := &walletrpc.BumpFeeRequest{
+		Outpoint: op,
+		// We use a force param to create the sweeping tx immediately.
+		Immediate: true,
+	}
+	err := alice.RPC.BumpFeeAssertErr(bumpFeeReq)
+	require.ErrorContains(ht, err, "does not belong to the wallet")
+
+	// Clean up the mempool.
+	ht.MineBlocksAndAssertNumTxes(1, 1)
+}
diff --git a/lntest/rpc/wallet_kit.go b/lntest/rpc/wallet_kit.go
index 41b596d4c..02e449cd8 100644
--- a/lntest/rpc/wallet_kit.go
+++ b/lntest/rpc/wallet_kit.go
@@ -254,6 +254,18 @@ func (h *HarnessRPC) BumpFee(
 	return resp
 }
 
+// BumpFeeAssertErr makes a RPC call to the node's WalletKitClient and asserts
+// that an error is returned.
+func (h *HarnessRPC) BumpFeeAssertErr(req *walletrpc.BumpFeeRequest) error {
+	ctxt, cancel := context.WithTimeout(h.runCtx, DefaultTimeout)
+	defer cancel()
+
+	_, err := h.WalletKit.BumpFee(ctxt, req)
+	require.Errorf(h, err, "%s: expect BumpFee to return an error", h.Name)
+
+	return err
+}
+
 // BumpForceCloseFee makes a RPC call to the node's WalletKitClient and asserts.
 //
 //nolint:ll