Make `test_duplicate_payment_hash_one_failure_one_success` robust

`test_duplicate_payment_hash_one_failure_one_success` currently
fails if the "wrong" HTLC is picked to be claimed. Given the HTLCs
are identical, there's no way to figure out which we should claim.
The test instead relies on a magic value - the first one is the
right one....unless we change our CSPRNG implementation. When we
try to do so, the test randomly fails.

Here we change one HTLC to a lower amount so we can figure out
which transaction to broadcast to make the test robust against
CSPRNG changes.

diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
index 9a6b3adc39aef9e1114d22ff292d62c76b76643b..8b71837d46a7bb1d9980dd587961cc38ccf1e095 100644 (file)
--- a/lightning/src/ln/functional_tests.rs
+++ b/lightning/src/ln/functional_tests.rs
@@ -4718,8 +4718,8 @@ fn test_duplicate_payment_hash_one_failure_one_success() {
        // ACCEPTED_HTLC_SCRIPT_WEIGHT.
        let payment_params = PaymentParameters::from_node_id(nodes[3].node.get_our_node_id())
                .with_features(nodes[3].node.invoice_features());
-       let (route, _, _, _) = get_route_and_payment_hash!(nodes[0], nodes[3], payment_params, 900000, TEST_FINAL_CLTV - 40);
-       send_along_route_with_secret(&nodes[0], route, &[&[&nodes[1], &nodes[2], &nodes[3]]], 900000, duplicate_payment_hash, payment_secret);
+       let (route, _, _, _) = get_route_and_payment_hash!(nodes[0], nodes[3], payment_params, 800_000, TEST_FINAL_CLTV - 40);
+       send_along_route_with_secret(&nodes[0], route, &[&[&nodes[1], &nodes[2], &nodes[3]]], 800_000, duplicate_payment_hash, payment_secret);
 
        let commitment_txn = get_local_commitment_txn!(nodes[2], chan_2.2);
        assert_eq!(commitment_txn[0].input.len(), 1);
@@ -4739,25 +4739,35 @@ fn test_duplicate_payment_hash_one_failure_one_success() {
 
                check_spends!(node_txn[0], commitment_txn[0]);
                assert_eq!(node_txn[0].input.len(), 1);
+               assert_eq!(node_txn[0].output.len(), 1);
 
                if node_txn.len() > 2 {
                        check_spends!(node_txn[1], commitment_txn[0]);
                        assert_eq!(node_txn[1].input.len(), 1);
+                       assert_eq!(node_txn[1].output.len(), 1);
                        assert_eq!(node_txn[0].input[0].previous_output, node_txn[1].input[0].previous_output);
 
                        check_spends!(node_txn[2], commitment_txn[0]);
+                       assert_eq!(node_txn[2].input.len(), 1);
+                       assert_eq!(node_txn[2].output.len(), 1);
                        assert_ne!(node_txn[0].input[0].previous_output, node_txn[2].input[0].previous_output);
                } else {
                        check_spends!(node_txn[1], commitment_txn[0]);
+                       assert_eq!(node_txn[1].input.len(), 1);
+                       assert_eq!(node_txn[1].output.len(), 1);
                        assert_ne!(node_txn[0].input[0].previous_output, node_txn[1].input[0].previous_output);
                }
 
                assert_eq!(node_txn[0].input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
                assert_eq!(node_txn[1].input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
+               // Assign htlc_timeout_tx to the forwarded HTLC (with value ~800 sats). The received HTLC
+               // (with value 900 sats) will be claimed in the below `claim_funds` call.
                if node_txn.len() > 2 {
                        assert_eq!(node_txn[2].input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
+                       htlc_timeout_tx = if node_txn[2].output[0].value < 900 { node_txn[2].clone() } else { node_txn[0].clone() };
+               } else {
+                       htlc_timeout_tx = if node_txn[0].output[0].value < 900 { node_txn[1].clone() } else { node_txn[0].clone() };
                }
-               htlc_timeout_tx = node_txn[0].clone();
        }
 
        nodes[2].node.claim_funds(our_payment_preimage);
@@ -4808,7 +4818,7 @@ fn test_duplicate_payment_hash_one_failure_one_success() {
        // Note that the fee paid is effectively double as the HTLC value (including the nodes[1] fee
        // and nodes[2] fee) is rounded down and then claimed in full.
        mine_transaction(&nodes[1], &htlc_success_txn[1]);
-       expect_payment_forwarded!(nodes[1], nodes[0], nodes[2], Some(196*2), true, true);
+       expect_payment_forwarded!(nodes[1], nodes[0], nodes[2], Some(196), true, true);
        let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
        assert!(updates.update_add_htlcs.is_empty());
        assert!(updates.update_fail_htlcs.is_empty());