Merge bitcoin/bitcoin#30554: test: Avoid CScript() as default function argument

fa46a1b74bd35371036af17b2df2036dbc993ce1 test: Avoid CScript() as default function argument (MarcoFalke)
fadf621825fdbf5fd131da14419bb19bb81e5801 test: Make leaf_script mandatory when scriptpath is set in TaprootSignatureMsg (MarcoFalke)

Pull request description:

  Unlike other function calls in default arguments, CScript should not cause any issues in the tests, because they are const.

  However, this change allows to enable the "function-call-in-default-argument (B008)" lint rule, which will help to catch severe test bugs, such as https://github.com/bitcoin/bitcoin/issues/30543#issuecomment-2259260024 .

  The lint rule will be enabled in a follow-up, when all violations are fixed.

ACKs for top commit:
  instagibbs:
    utACK fa46a1b74bd35371036af17b2df2036dbc993ce1
  theStack:
    lgtm ACK fa46a1b74bd35371036af17b2df2036dbc993ce1
  ismaelsadeeq:
    Tested ACK fa46a1b74bd35371036af17b2df2036dbc993ce1

Tree-SHA512: bc68b15121d50ead0fc70ad772360a7829908aedeaff8426efcb8a67f33117f67d26b4f5da94fa735dd8de9c9ff65fc10a29323f1b12f238b75486fa7cc32a89

5 files changed, 24 insertions, 16 deletions

diff --git a/test/functional/data/invalid_txs.py b/test/functional/data/invalid_txs.py
index 33054fd517..2e4ca83bf0 100644
--- a/test/functional/data/invalid_txs.py
+++ b/test/functional/data/invalid_txs.py
@@ -192,7 +192,7 @@ class SpendTooMuch(BadTxTemplate):
 
     def get_tx(self):
         return create_tx_with_script(
-            self.spend_tx, 0, script_pub_key=basic_p2sh, amount=(self.spend_avail + 1))
+            self.spend_tx, 0, output_script=basic_p2sh, amount=(self.spend_avail + 1))
 
 
 class CreateNegative(BadTxTemplate):
@@ -242,7 +242,7 @@ class TooManySigops(BadTxTemplate):
         lotsa_checksigs = CScript([OP_CHECKSIG] * (MAX_BLOCK_SIGOPS))
         return create_tx_with_script(
             self.spend_tx, 0,
-            script_pub_key=lotsa_checksigs,
+            output_script=lotsa_checksigs,
             amount=1)
 
 def getDisabledOpcodeTemplate(opcode):
diff --git a/test/functional/feature_block.py b/test/functional/feature_block.py
index 172af27848..384ca311c7 100755
--- a/test/functional/feature_block.py
+++ b/test/functional/feature_block.py
@@ -1326,8 +1326,10 @@ class FullBlockTest(BitcoinTestFramework):
         block.vtx.extend(tx_list)
 
     # this is a little handier to use than the version in blocktools.py
-    def create_tx(self, spend_tx, n, value, script=CScript([OP_TRUE, OP_DROP] * 15 + [OP_TRUE])):
-        return create_tx_with_script(spend_tx, n, amount=value, script_pub_key=script)
+    def create_tx(self, spend_tx, n, value, output_script=None):
+        if output_script is None:
+            output_script = CScript([OP_TRUE, OP_DROP] * 15 + [OP_TRUE])
+        return create_tx_with_script(spend_tx, n, amount=value, output_script=output_script)
 
     # sign a transaction, using the key we know about
     # this signs input 0 in tx, which is assumed to be spending output 0 in spend_tx
@@ -1338,13 +1340,17 @@ class FullBlockTest(BitcoinTestFramework):
             return
         sign_input_legacy(tx, 0, spend_tx.vout[0].scriptPubKey, self.coinbase_key)
 
-    def create_and_sign_transaction(self, spend_tx, value, script=CScript([OP_TRUE])):
-        tx = self.create_tx(spend_tx, 0, value, script)
+    def create_and_sign_transaction(self, spend_tx, value, output_script=None):
+        if output_script is None:
+            output_script = CScript([OP_TRUE])
+        tx = self.create_tx(spend_tx, 0, value, output_script=output_script)
         self.sign_tx(tx, spend_tx)
         tx.rehash()
         return tx
 
-    def next_block(self, number, spend=None, additional_coinbase_value=0, script=CScript([OP_TRUE]), *, version=4):
+    def next_block(self, number, spend=None, additional_coinbase_value=0, *, script=None, version=4):
+        if script is None:
+            script = CScript([OP_TRUE])
         if self.tip is None:
             base_block_hash = self.genesis_hash
             block_time = int(time.time()) + 1
@@ -1361,7 +1367,7 @@ class FullBlockTest(BitcoinTestFramework):
         else:
             coinbase.vout[0].nValue += spend.vout[0].nValue - 1  # all but one satoshi to fees
             coinbase.rehash()
-            tx = self.create_tx(spend, 0, 1, script)  # spend 1 satoshi
+            tx = self.create_tx(spend, 0, 1, output_script=script)  # spend 1 satoshi
             self.sign_tx(tx, spend)
             tx.rehash()
             block = create_block(base_block_hash, coinbase, block_time, version=version, txlist=[tx])
diff --git a/test/functional/feature_taproot.py b/test/functional/feature_taproot.py
index b2e030adc7..443c1c33da 100755
--- a/test/functional/feature_taproot.py
+++ b/test/functional/feature_taproot.py
@@ -231,7 +231,7 @@ def default_sigmsg(ctx):
             codeseppos = get(ctx, "codeseppos")
             leaf_ver = get(ctx, "leafversion")
             script = get(ctx, "script_taproot")
-            return TaprootSignatureMsg(tx, utxos, hashtype, idx, scriptpath=True, script=script, leaf_ver=leaf_ver, codeseparator_pos=codeseppos, annex=annex)
+            return TaprootSignatureMsg(tx, utxos, hashtype, idx, scriptpath=True, leaf_script=script, leaf_ver=leaf_ver, codeseparator_pos=codeseppos, annex=annex)
         else:
             return TaprootSignatureMsg(tx, utxos, hashtype, idx, scriptpath=False, annex=annex)
     elif mode == "witv0":
diff --git a/test/functional/test_framework/blocktools.py b/test/functional/test_framework/blocktools.py
index 338b7fa3b0..5c2fa28a31 100644
--- a/test/functional/test_framework/blocktools.py
+++ b/test/functional/test_framework/blocktools.py
@@ -154,16 +154,18 @@ def create_coinbase(height, pubkey=None, *, script_pubkey=None, extra_output_scr
     coinbase.calc_sha256()
     return coinbase
 
-def create_tx_with_script(prevtx, n, script_sig=b"", *, amount, script_pub_key=CScript()):
+def create_tx_with_script(prevtx, n, script_sig=b"", *, amount, output_script=None):
     """Return one-input, one-output transaction object
        spending the prevtx's n-th output with the given amount.
 
        Can optionally pass scriptPubKey and scriptSig, default is anyone-can-spend output.
     """
+    if output_script is None:
+        output_script = CScript()
     tx = CTransaction()
     assert n < len(prevtx.vout)
     tx.vin.append(CTxIn(COutPoint(prevtx.sha256, n), script_sig, SEQUENCE_FINAL))
-    tx.vout.append(CTxOut(amount, script_pub_key))
+    tx.vout.append(CTxOut(amount, output_script))
     tx.calc_sha256()
     return tx
 
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
index 97d62f957b..d510cf9b1c 100644
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -810,7 +810,7 @@ def BIP341_sha_sequences(txTo):
 def BIP341_sha_outputs(txTo):
     return sha256(b"".join(o.serialize() for o in txTo.vout))
 
-def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpath = False, script = CScript(), codeseparator_pos = -1, annex = None, leaf_ver = LEAF_VERSION_TAPSCRIPT):
+def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index=0, *, scriptpath=False, leaf_script=None, codeseparator_pos=-1, annex=None, leaf_ver=LEAF_VERSION_TAPSCRIPT):
     assert (len(txTo.vin) == len(spent_utxos))
     assert (input_index < len(txTo.vin))
     out_type = SIGHASH_ALL if hash_type == 0 else hash_type & 3
@@ -829,7 +829,7 @@ def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpat
     spend_type = 0
     if annex is not None:
         spend_type |= 1
-    if (scriptpath):
+    if scriptpath:
         spend_type |= 2
     ss += bytes([spend_type])
     if in_type == SIGHASH_ANYONECANPAY:
@@ -846,11 +846,11 @@ def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpat
             ss += sha256(txTo.vout[input_index].serialize())
         else:
             ss += bytes(0 for _ in range(32))
-    if (scriptpath):
-        ss += TaggedHash("TapLeaf", bytes([leaf_ver]) + ser_string(script))
+    if scriptpath:
+        ss += TaggedHash("TapLeaf", bytes([leaf_ver]) + ser_string(leaf_script))
         ss += bytes([0])
         ss += codeseparator_pos.to_bytes(4, "little", signed=True)
-    assert len(ss) ==  175 - (in_type == SIGHASH_ANYONECANPAY) * 49 - (out_type != SIGHASH_ALL and out_type != SIGHASH_SINGLE) * 32 + (annex is not None) * 32 + scriptpath * 37
+    assert len(ss) == 175 - (in_type == SIGHASH_ANYONECANPAY) * 49 - (out_type != SIGHASH_ALL and out_type != SIGHASH_SINGLE) * 32 + (annex is not None) * 32 + scriptpath * 37
     return ss
 
 def TaprootSignatureHash(*args, **kwargs):