test: use MiniWallet for p2p_segwit.py

This change only affects the subtest `test_superfluous_witness`.

Note that instead of creating a raw transaction first and then
signing it, we go the other direction here: MiniWallet creates a
transaction spending a segwit v1 output (i.e. including a witness),
then we turn it into a raw transaction by dropping the witness.
Therefore, the debug log asserts are swapped.

test/functional/p2p_segwit.py

@@ -43,7 +43,6 @@ from test_framework.messages import (
     ser_uint256,
     ser_vector,
     sha256,
-    tx_from_hex,
 )
 from test_framework.p2p import (
     P2PInterface,
@@ -89,6 +88,8 @@ from test_framework.util import (
     softfork_active,
     assert_raises_rpc_error,
 )
+from test_framework.wallet import MiniWallet
+
 
 MAX_SIGOP_COST = 80000
 
@@ -221,9 +222,6 @@ class SegWitTest(BitcoinTestFramework):
         ]
         self.supports_cli = False
 
-    def skip_test_if_missing_module(self):
-        self.skip_if_no_wallet()
-
     # Helper functions
 
     def build_next_block(self):
@@ -259,6 +257,7 @@ class SegWitTest(BitcoinTestFramework):
 
         self.log.info("Starting tests before segwit activation")
         self.segwit_active = False
+        self.wallet = MiniWallet(self.nodes[0])
 
         self.test_non_witness_transaction()
         self.test_v0_outputs_arent_spendable()
@@ -307,7 +306,7 @@ class SegWitTest(BitcoinTestFramework):
         self.test_node.send_and_ping(msg_no_witness_block(block))  # make sure the block was processed
         txid = block.vtx[0].sha256
 
-        self.generate(self.nodes[0], 99)  # let the block mature
+        self.generate(self.wallet, 99)  # let the block mature
 
         # Create a transaction that spends the coinbase
         tx = CTransaction()
@@ -1999,22 +1998,14 @@ class SegWitTest(BitcoinTestFramework):
             def serialize(self):
                 return serialize_with_bogus_witness(self.tx)
 
-        self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(address_type='bech32'), 5)
+        tx = self.wallet.create_self_transfer(from_node=self.nodes[0])['tx']
-        self.generate(self.nodes[0], 1)
-        unspent = next(u for u in self.nodes[0].listunspent() if u['spendable'] and u['address'].startswith('bcrt'))
-
-        raw = self.nodes[0].createrawtransaction([{"txid": unspent['txid'], "vout": unspent['vout']}], {self.nodes[0].getnewaddress(): 1})
-        tx = tx_from_hex(raw)
-        assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].decoderawtransaction, hexstring=serialize_with_bogus_witness(tx).hex(), iswitness=True)
-        with self.nodes[0].assert_debug_log(['Superfluous witness record']):
-            self.test_node.send_and_ping(msg_bogus_tx(tx))
-        raw = self.nodes[0].signrawtransactionwithwallet(raw)
-        assert raw['complete']
-        raw = raw['hex']
-        tx = tx_from_hex(raw)
         assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].decoderawtransaction, hexstring=serialize_with_bogus_witness(tx).hex(), iswitness=True)
         with self.nodes[0].assert_debug_log(['Unknown transaction optional data']):
             self.test_node.send_and_ping(msg_bogus_tx(tx))
+        tx.wit.vtxinwit = []  # drop witness
+        assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].decoderawtransaction, hexstring=serialize_with_bogus_witness(tx).hex(), iswitness=True)
+        with self.nodes[0].assert_debug_log(['Superfluous witness record']):
+            self.test_node.send_and_ping(msg_bogus_tx(tx))
 
     @subtest
     def test_wtxid_relay(self):