ln/tests: return BlindedPaymentPath from trampoline helper

diff --git a/lightning/src/ln/blinded_payment_tests.rs b/lightning/src/ln/blinded_payment_tests.rs
index e4538e4..c67c593 100644
--- a/lightning/src/ln/blinded_payment_tests.rs
+++ b/lightning/src/ln/blinded_payment_tests.rs
@@ -2580,6 +2580,39 @@ fn do_test_trampoline_relay(blinded: bool, test_case: TrampolineTestCase) {
 	let override_random_bytes = [42; 32];
 	*nodes[0].keys_manager.override_random_bytes.lock().unwrap() = Some(override_random_bytes);
 
+	// Create a blinded tail where Carol is receiving. In our unblinded test cases, we'll
+	// override this anyway (with a tail sending to an unblinded receive, which LDK doesn't
+	// allow).
+	let (blinded_tail, blinded_path) = create_trampoline_forward_blinded_tail(
+		&secp_ctx,
+		&nodes[2].keys_manager,
+		&[],
+		carol_node_id,
+		nodes[2].keys_manager.get_receive_auth_key(),
+		ReceiveTlvs {
+			payment_secret,
+			payment_constraints: PaymentConstraints {
+				max_cltv_expiry: u32::max_value(),
+				htlc_minimum_msat: original_amt_msat,
+			},
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {
+				payment_metadata: None,
+			}),
+		},
+		original_trampoline_cltv,
+		excess_final_cltv,
+		original_amt_msat,
+	);
+
+	// When Carol receives over the blinded path, register it in the payment parameters as we
+	// would for a real blinded payment. In the unblinded test cases the blinded tail is overridden,
+	// so the payee is just Carol's unblinded node id.
+	let payment_params = if blinded {
+		PaymentParameters::blinded(vec![blinded_path])
+	} else {
+		PaymentParameters::from_node_id(carol_node_id, original_trampoline_cltv + excess_final_cltv)
+	};
+
 	let route = Route {
 		paths: vec![Path {
 			hops: vec![
@@ -2602,35 +2635,10 @@ fn do_test_trampoline_relay(blinded: bool, test_case: TrampolineTestCase) {
 					maybe_announced_channel: false,
 				},
 			],
-			// Create a blinded tail where Carol is receiving. In our unblinded test cases, we'll
-			// override this anyway (with a tail sending to an unblinded receive, which LDK doesn't
-			// allow).
-			blinded_tail: Some(create_trampoline_forward_blinded_tail(
-				&secp_ctx,
-				&nodes[2].keys_manager,
-				&[],
-				carol_node_id,
-				nodes[2].keys_manager.get_receive_auth_key(),
-				ReceiveTlvs {
-					payment_secret,
-					payment_constraints: PaymentConstraints {
-						max_cltv_expiry: u32::max_value(),
-						htlc_minimum_msat: original_amt_msat,
-					},
-					payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {
-						payment_metadata: None,
-					}),
-				},
-				original_trampoline_cltv,
-				excess_final_cltv,
-				original_amt_msat,
-			)),
+			blinded_tail: Some(blinded_tail),
 		}],
 		route_params: RouteParameters::from_payment_params_and_value(
-			PaymentParameters::from_node_id(
-				carol_node_id,
-				original_trampoline_cltv + excess_final_cltv,
-			),
+			payment_params,
 			original_amt_msat,
 		),
 	};
diff --git a/lightning/src/ln/functional_test_utils.rs b/lightning/src/ln/functional_test_utils.rs
index 6e855c2..475764e 100644
--- a/lightning/src/ln/functional_test_utils.rs
+++ b/lightning/src/ln/functional_test_utils.rs
@@ -5780,12 +5780,16 @@ pub fn get_scid_from_channel_id<'a, 'b, 'c>(node: &Node<'a, 'b, 'c>, channel_id:
 ///
 /// The resulting tail contains blinded hops built from `intermediate_nodes` plus a dummy receive
 /// TLV, with the `TrampolineHop` fee and CLTV derived from the blinded path's aggregated payinfo.
+/// The constructed [`BlindedPaymentPath`] is also returned so callers can register it in
+/// [`PaymentParameters`].
+///
+/// [`PaymentParameters`]: crate::routing::router::PaymentParameters
 pub fn create_trampoline_forward_blinded_tail<ES: EntropySource>(
 	secp_ctx: &bitcoin::secp256k1::Secp256k1<bitcoin::secp256k1::All>, entropy_source: ES,
 	intermediate_nodes: &[ForwardNode<TrampolineForwardTlvs>], payee_node_id: PublicKey,
 	payee_receive_key: ReceiveAuthKey, payee_tlvs: ReceiveTlvs, min_final_cltv_expiry_delta: u32,
 	excess_final_cltv_delta: u32, final_value_msat: u64,
-) -> BlindedTail {
+) -> (BlindedTail, BlindedPaymentPath) {
 	let blinded_path = BlindedPaymentPath::new_for_trampoline(
 		intermediate_nodes,
 		payee_node_id,
@@ -5798,7 +5802,7 @@ pub fn create_trampoline_forward_blinded_tail<ES: EntropySource>(
 	)
 	.unwrap();
 
-	BlindedTail {
+	let tail = BlindedTail {
 		trampoline_hops: vec![TrampolineHop {
 			pubkey: intermediate_nodes.first().map(|n| n.node_id).unwrap_or(payee_node_id),
 			node_features: types::features::Features::empty(),
@@ -5817,5 +5821,6 @@ pub fn create_trampoline_forward_blinded_tail<ES: EntropySource>(
 		blinding_point: blinded_path.blinding_point(),
 		excess_final_cltv_expiry_delta: excess_final_cltv_delta,
 		final_value_msat,
-	}
+	};
+	(tail, blinded_path)
 }