[functional] Add mempool_wtxid.py

Antoine Riard · Antoine Riard · commit d86e7a17081a · 2020-08-06T05:25:43.000-04:00
Broadcast consequently two identical child transactions with size-divergent
witnesses and thus different feerate. The second broadcast should successfully
replace the first one.

Add assert_not_equal helper in test_framework/util.py
diff --git a/test/functional/mempool_wtxid.py b/test/functional/mempool_wtxid.py
@@ -0,0 +1,110 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test mempool wtxid acceptance in case of an already known transaction
+with identical non-witness data but lower feerate witness."""
+
+from codecs import encode
+from decimal import Decimal
+
+from test_framework.test_framework import BitcoinTestFramework
+
+from test_framework.messages import (
+        CTransaction,
+        CTxIn,
+        CTxInWitness,
+        CTxOut,
+        COutPoint,
+        sha256,
+        COIN,
+        hash256,
+)
+
+from test_framework.util import (
+        assert_equal,
+        assert_not_equal,
+)
+
+from test_framework.script import (
+        CScript,
+        OP_0,
+        OP_TRUE,
+        OP_IF,
+        OP_HASH160,
+        OP_EQUAL,
+        OP_ELSE,
+        OP_ENDIF,
+        hash160,
+)
+
+class MempoolWtxidTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.supports_cli = False
+        self.extra_args = [["-incrementalrelayfee=0"]]
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        node = self.nodes[0]
+
+        self.log.info('Start with empty mempool, and 200 blocks')
+        self.mempool_size = 0
+        assert_equal(node.getblockcount(), 200)
+        assert_equal(node.getmempoolinfo()['size'], self.mempool_size)
+
+        txid = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), Decimal("10"))
+
+        # Create a Segwit output
+        hashlock = hash160(b'Preimage')
+        witness_script = CScript([OP_IF, OP_HASH160, hashlock, OP_EQUAL, OP_ELSE, OP_TRUE, OP_ENDIF])
+        witness_program = sha256(witness_script)
+        script_pubkey = CScript([OP_0, witness_program])
+
+        parent = CTransaction()
+        parent.vin.append(CTxIn(COutPoint(int(txid, 16), 0), b""))
+        parent.vout.append(CTxOut(int(9.99998 * COIN), script_pubkey))
+        parent.rehash()
+
+        # Confirm parent with alternative script branches witnessScript
+        raw_parent = self.nodes[0].signrawtransactionwithwallet(parent.serialize().hex())['hex']
+        parent_txid = self.nodes[0].sendrawtransaction(hexstring=raw_parent, maxfeerate=0)
+        self.nodes[0].generate(1)
+
+        # Create a new segwit transaction with witness solving first branch
+        child_witness_script = CScript([OP_TRUE])
+        child_witness_program = sha256(child_witness_script)
+        child_script_pubkey = CScript([OP_0, child_witness_program])
+
+        child_one = CTransaction()
+        child_one.vin.append(CTxIn(COutPoint(int(parent_txid, 16), 0), b""))
+        child_one.vout.append(CTxOut(int(9.99996 * COIN), child_script_pubkey))
+        child_one.wit.vtxinwit.append(CTxInWitness())
+        child_one.wit.vtxinwit[0].scriptWitness.stack = [b'Preimage', b'\x01', witness_script]
+        child_one_txid = self.nodes[0].sendrawtransaction(hexstring=child_one.serialize().hex())
+        child_one_wtxid = encode(hash256(child_one.serialize_with_witness())[::-1], 'hex_codec').decode('ascii')
+
+        self.log.info('Verify that transaction with lower-feerate witness gets in the mempool')
+        in_mempool_wtxid = self.nodes[0].getrawmempool(True)[child_one_txid]['wtxid']
+        assert_equal(child_one_wtxid, in_mempool_wtxid)
+
+        # Create another identical segwit transaction with witness solving second branch
+        child_two = CTransaction()
+        child_two.vin.append(CTxIn(COutPoint(int(parent_txid, 16), 0), b""))
+        child_two.vout.append(CTxOut(int(9.99996 * COIN), child_script_pubkey))
+        child_two.wit.vtxinwit.append(CTxInWitness())
+        child_two.wit.vtxinwit[0].scriptWitness.stack = [b'', witness_script]
+        child_two_txid = self.nodes[0].sendrawtransaction(hexstring=child_two.serialize().hex())
+        child_two_wtxid = encode(hash256(child_two.serialize_with_witness())[::-1], 'hex_codec').decode('ascii')
+
+        assert_equal(child_one_txid, child_two_txid)
+        assert_not_equal(child_one_wtxid, child_two_wtxid)
+
+        self.log.info('Verify that identical transaction with higher-feerate witness gets in the mempool')
+        in_mempool_wtxid = self.nodes[0].getrawmempool(True)[child_one_txid]['wtxid']
+        assert_equal(child_two_wtxid, in_mempool_wtxid)
+
+if __name__ == '__main__':
+    MempoolWtxidTest().main()
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
@@ -49,6 +49,11 @@ def assert_equal(thing1, thing2, *args):
         raise AssertionError("not(%s)" % " == ".join(str(arg) for arg in (thing1, thing2) + args))
 
 
+def assert_not_equal(thing1, thing2, *args):
+    if thing1 == thing2 or any(thing1 == arg for arg in args):
+        raise AssertionError("not(%s)" % " != ".join(str(arg) for arg in (thing1, thing2) + args))
+
+
 def assert_greater_than(thing1, thing2):
     if thing1 <= thing2:
         raise AssertionError("%s <= %s" % (str(thing1), str(thing2)))
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
@@ -234,6 +234,7 @@
     'feature_asmap.py',
     'mempool_unbroadcast.py',
     'mempool_compatibility.py',
+    'mempool_wtxid.py',
     'rpc_deriveaddresses.py',
     'rpc_deriveaddresses.py --usecli',
     'p2p_ping.py',
