Merge bitcoin/bitcoin#22330: test: use MiniWallet for simple doublespend sub-test in feature_rbf.py

aa02c64540 test: use MiniWallet for simple doublespend test in feature_rbf.py (Sebastian Falbesoner)
a3f6397c73 test: feature_rbf.py: make MiniWallet instance available for all sub-tests (Sebastian Falbesoner)
84c874794c test: remove unneeded initialization code in feature_rbf.py (Sebastian Falbesoner)

Pull request description:

  This PR's goal is to prepare the functional test `feature_rbf.py` for more MiniWallet usage. It first gets rid of unused initialization code (I guess that was needed at times when the nodes were still in IBD at the start of tests?), then makes the MiniWallet instance introduced in #22210 available for all sub-tests, and finally, uses that instance in the first sub-test `test_simple_doublespend`.

  Note that the same idea of replacing the `make_utxo` calls with MiniWallet can be also applied to other sub-tests too; this just serves as a first proof-of-concept.

ACKs for top commit:
  MarcoFalke:
    re-ACK aa02c64540 🌯

Tree-SHA512: 2902dd15d493d83b0790028c92d14fbd99ca05ace704c7011fb38261ce6517aeb810ef9f360fcb701d95887975b6a2911cfe538858d38fceb2c1c2a40afdbe6b

test/functional/feature_rbf.py

@@ -4,6 +4,7 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the RBF code."""
 
+from copy import deepcopy
 from decimal import Decimal
 
 from test_framework.blocktools import COINBASE_MATURITY
@@ -84,10 +85,11 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         self.skip_if_no_wallet()
 
     def run_test(self):
-        make_utxo(self.nodes[0], 1 * COIN)
-
-        # Ensure nodes are synced
-        self.sync_all()
+        self.wallet = MiniWallet(self.nodes[0])
+        # the pre-mined test framework chain contains coinbase outputs to the
+        # MiniWallet's default address ADDRESS_BCRT1_P2WSH_OP_TRUE in blocks
+        # 76-100 (see method BitcoinTestFramework._initialize_chain())
+        self.wallet.scan_blocks(start=76, num=2)
 
         self.log.info("Running test simple doublespend...")
         self.test_simple_doublespend()
@@ -129,24 +131,17 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
     def test_simple_doublespend(self):
         """Simple doublespend"""
-        tx0_outpoint = make_utxo(self.nodes[0], int(1.1 * COIN))
-
-        # make_utxo may have generated a bunch of blocks, so we need to sync
-        # before we can spend the coins generated, or else the resulting
-        # transactions might not be accepted by our peers.
-        self.sync_all()
+        # we use MiniWallet to create a transaction template with inputs correctly set,
+        # and modify the output (amount, scriptPubKey) according to our needs
+        tx_template = self.wallet.create_self_transfer(from_node=self.nodes[0])['tx']
 
-        tx1a = CTransaction()
-        tx1a.vin = [CTxIn(tx0_outpoint, nSequence=0)]
+        tx1a = deepcopy(tx_template)
         tx1a.vout = [CTxOut(1 * COIN, DUMMY_P2WPKH_SCRIPT)]
         tx1a_hex = tx1a.serialize().hex()
         tx1a_txid = self.nodes[0].sendrawtransaction(tx1a_hex, 0)
 
-        self.sync_all()
-
         # Should fail because we haven't changed the fee
-        tx1b = CTransaction()
-        tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
+        tx1b = deepcopy(tx_template)
         tx1b.vout = [CTxOut(1 * COIN, DUMMY_2_P2WPKH_SCRIPT)]
         tx1b_hex = tx1b.serialize().hex()
 
@@ -154,9 +149,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         assert_raises_rpc_error(-26, "insufficient fee", self.nodes[0].sendrawtransaction, tx1b_hex, 0)
 
         # Extra 0.1 BTC fee
-        tx1b = CTransaction()
-        tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        tx1b.vout = [CTxOut(int(0.9 * COIN), DUMMY_P2WPKH_SCRIPT)]
+        tx1b.vout[0].nValue -= int(0.1 * COIN)
         tx1b_hex = tx1b.serialize().hex()
         # Works when enabled
         tx1b_txid = self.nodes[0].sendrawtransaction(tx1b_hex, 0)
@@ -574,12 +567,10 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         assert_equal(json1["vin"][0]["sequence"], 4294967294)
 
     def test_no_inherited_signaling(self):
-        wallet = MiniWallet(self.nodes[0])
-        wallet.scan_blocks(start=76, num=1)
-        confirmed_utxo = wallet.get_utxo()
+        confirmed_utxo = self.wallet.get_utxo()
 
         # Create an explicitly opt-in parent transaction
-        optin_parent_tx = wallet.send_self_transfer(
+        optin_parent_tx = self.wallet.send_self_transfer(
             from_node=self.nodes[0],
             utxo_to_spend=confirmed_utxo,
             sequence=BIP125_SEQUENCE_NUMBER,
@@ -587,7 +578,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         )
         assert_equal(True, self.nodes[0].getmempoolentry(optin_parent_tx['txid'])['bip125-replaceable'])
 
-        replacement_parent_tx = wallet.create_self_transfer(
+        replacement_parent_tx = self.wallet.create_self_transfer(
             from_node=self.nodes[0],
             utxo_to_spend=confirmed_utxo,
             sequence=BIP125_SEQUENCE_NUMBER,
@@ -601,8 +592,8 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         assert_equal(res['allowed'], True)
 
         # Create an opt-out child tx spending the opt-in parent
-        parent_utxo = wallet.get_utxo(txid=optin_parent_tx['txid'])
-        optout_child_tx = wallet.send_self_transfer(
+        parent_utxo = self.wallet.get_utxo(txid=optin_parent_tx['txid'])
+        optout_child_tx = self.wallet.send_self_transfer(
             from_node=self.nodes[0],
             utxo_to_spend=parent_utxo,
             sequence=0xffffffff,
@@ -612,7 +603,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         # Reports true due to inheritance
         assert_equal(True, self.nodes[0].getmempoolentry(optout_child_tx['txid'])['bip125-replaceable'])
 
-        replacement_child_tx = wallet.create_self_transfer(
+        replacement_child_tx = self.wallet.create_self_transfer(
             from_node=self.nodes[0],
             utxo_to_spend=parent_utxo,
             sequence=0xffffffff,
@@ -631,9 +622,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         assert_raises_rpc_error(-26, 'txn-mempool-conflict', self.nodes[0].sendrawtransaction, replacement_child_tx["hex"], 0)
 
     def test_replacement_relay_fee(self):
-        wallet = MiniWallet(self.nodes[0])
-        wallet.scan_blocks(start=77, num=1)
-        tx = wallet.send_self_transfer(from_node=self.nodes[0])['tx']
+        tx = self.wallet.send_self_transfer(from_node=self.nodes[0])['tx']
 
         # Higher fee, higher feerate, different txid, but the replacement does not provide a relay
         # fee conforming to node's `incrementalrelayfee` policy of 1000 sat per KB.