Merge bitcoin/bitcoin#29939: test: add MiniWallet tagging support to avoid UTXO mixing, use in `fill_mempool`

dd8fa861939d5b8bdd844ad7cab015d08533a91a test: use tagged ephemeral MiniWallet instance in fill_mempool (Sebastian Falbesoner)
b2037ad4aeb4e16c7eb1e5756d0d1ee20172344b test: add MiniWallet tagging support to avoid UTXO mixing (Sebastian Falbesoner)
c8e6d08236ff225db445009bf513d6d25def8eb2 test: refactor: eliminate COINBASE_MATURITY magic number in fill_mempool (Sebastian Falbesoner)
4f347140b1a31237597dd1821adcde8bd5761edc test: refactor: move fill_mempool to new module mempool_util (Sebastian Falbesoner)

Pull request description:

  Different MiniWallet instances using the same mode (either ADDRESS_OP_TRUE, RAW_OP_TRUE or RAW_P2PK) currently always create and spend UTXOs with identical output scripts, which can cause unintentional tx dependencies (see e.g. the discussion in https://github.com/bitcoin/bitcoin/pull/29827#discussion_r1565443465). In order to avoid mixing of UTXOs between instances, this PR introduces the possibility to provide a MiniWallet tag name, that is used to derive a different internal key for the taproot construction, leading to a different P2TR output script. Note that since we use script-path spending and only the key-path is changed here, no changes in the MiniWallet spending logic are needed.

  The new tagging option is then used in the `fill_mempool` helper to create an ephemeral wallet for the filling txs, as suggested in https://github.com/bitcoin/bitcoin/pull/29827#discussion_r1565964264. To avoid circular dependencies, `fill_mempool` is moved to a new module `mempool_util.py` first.

  I'm still not sure if a generic word like "tag" is the right term for what this tries to achieve, happy to pick up better suggestions. Also, maybe passing a tag name is overkill and a boolean flag like "random_output_script" is sufficient?

ACKs for top commit:
  glozow:
    ACK dd8fa861939
  achow101:
    ACK dd8fa861939d5b8bdd844ad7cab015d08533a91a
  rkrux:
    tACK [dd8fa86](https://github.com/bitcoin/bitcoin/pull/29939/commits/dd8fa861939d5b8bdd844ad7cab015d08533a91a)
  brunoerg:
    utACK dd8fa861939d5b8bdd844ad7cab015d08533a91a

Tree-SHA512: 5ef3558c3ef5ac32cfa79c8f751972ca6bceaa332cd7daac7e93412a88e30dec472cb041c0845b04abf8a317036d31ebddfc3234e609ed442417894c2bdeeac9

1 files changed, 4 insertions, 3 deletions

diff --git a/test/functional/p2p_opportunistic_1p1c.py b/test/functional/p2p_opportunistic_1p1c.py
index e07acd5481..aec6e95fbc 100755
--- a/test/functional/p2p_opportunistic_1p1c.py
+++ b/test/functional/p2p_opportunistic_1p1c.py
@@ -8,6 +8,9 @@ Test opportunistic 1p1c package submission logic.
 
 from decimal import Decimal
 import time
+from test_framework.mempool_util import (
+    fill_mempool,
+)
 from test_framework.messages import (
     CInv,
     CTxInWitness,
@@ -24,7 +27,6 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
     assert_greater_than,
-    fill_mempool,
 )
 from test_framework.wallet import (
     MiniWallet,
@@ -386,8 +388,7 @@ class PackageRelayTest(BitcoinTestFramework):
         self.generate(self.wallet_nonsegwit, 10)
         self.generate(self.wallet, 20)
 
-        filler_wallet = MiniWallet(node)
-        fill_mempool(self, node, filler_wallet)
+        fill_mempool(self, node)
 
         self.log.info("Check opportunistic 1p1c logic when parent (txid != wtxid) is received before child")
         self.test_basic_parent_then_child(self.wallet)