QA: feature_rbf: Check opt-in RBF with TRUC signal

Author: luke-jr

test/functional/feature_rbf.py

@@ -34,6 +34,8 @@ def set_test_params(self):
                 "-limitancestorsize=101",
                 "-limitdescendantcount=200",
                 "-limitdescendantsize=101",
+                "-mempooltruc=accept",
+                "-paytxfee=0.00001",  # this test confuses the fee estimator into nearly 1 BTC fees
             ],
             # second node has default mempool parameters, besides mempoolfullrbf being disabled
             [
@@ -99,8 +101,10 @@ def test_service_flag():
 
         self.log.info("Running test opt-in...")
         self.test_opt_in(fullrbf=False)
+        self.test_opt_in(fullrbf=False, use_truc=True)
         self.nodes[0], self.nodes[-1] = self.nodes[-1], self.nodes[0]
         self.test_opt_in(fullrbf=True)
+        self.test_opt_in(fullrbf=True, use_truc=True)
         self.nodes[0], self.nodes[-1] = self.nodes[-1], self.nodes[0]
 
         self.log.info("Running test RPC...")
@@ -513,7 +517,7 @@ def test_too_many_replacements_with_default_mempool_params(self):
         self.generate(normal_node, 1)
         self.wallet.rescan_utxos()
 
-    def test_opt_in(self, fullrbf):
+    def test_opt_in(self, fullrbf, use_truc=False):
         """Replacing should only work if orig tx opted in"""
         tx0_outpoint = self.make_utxo(self.nodes[0], int(1.1 * COIN))
 
@@ -572,15 +576,24 @@ def test_opt_in(self, fullrbf):
         # opt-in on one of the inputs
         # Transaction should be replaceable on either input
 
+        self.generate(self.nodes[0], 1)  # clean mempool so parent txs don't trigger BIP125
+        if use_truc:
+            kwargs = {'sequence': SEQUENCE_FINAL, 'version': 3}
+        else:
+            kwargs = {'sequence': [SEQUENCE_FINAL, 0xfffffffd]}
+
         tx3a_txid = self.wallet.send_self_transfer_multi(
             from_node=self.nodes[0],
             utxos_to_spend=[tx1a_utxo, tx2a_utxo],
-            sequence=[SEQUENCE_FINAL, 0xfffffffd],
             fee_per_output=int(0.1 * COIN),
+            **kwargs
         )["txid"]
 
         # This transaction is shown as replaceable
-        assert_equal(self.nodes[0].getmempoolentry(tx3a_txid)['bip125-replaceable'], True)
+        if use_truc:
+            assert_equal(self.nodes[0].getmempoolentry(tx3a_txid)['bip125-replaceable'], False)
+        else:
+            assert_equal(self.nodes[0].getmempoolentry(tx3a_txid)['bip125-replaceable'], True)
 
         self.wallet.send_self_transfer(
             from_node=self.nodes[0],