Merge bitcoin/bitcoin#24941: test: MiniWallet: support skipping mempool checks (feature_fee_estimation.py performance fix)

a498acce4514d83d8dafcebaad522a89b6dc70fa test: MiniWallet: skip mempool check if `mempool_valid=False` (Sebastian Falbesoner)
01552e8f677b710944a0c41406253bc3102db332 test: MiniWallet: always rehash after signing (P2PK mode) (Sebastian Falbesoner)

Pull request description:

  MiniWallet's core method for creating txs (`create_self_transfer`) right now always executes the `testmempoolaccept` RPC to check for mempool validity or invalidity. In some test cases where we use MiniWallet to create a huge number of transactions this can lead to performance issues, in particular feature_fee_estimation.py where the execution time after MiniWallet usage (PR #24817) doubled, see https://github.com/bitcoin/bitcoin/issues/24828#issuecomment-1100058100, https://github.com/bitcoin/bitcoin/issues/24828#issuecomment-1100301980. This PR mitigates this by skipping the mempool check if the parameter `mempool_valid` is set to `False`.

  As a preparatory commit, the test feature_csv_activation.py has to be adapted w.r.t. to rehashing of transactions, as we now hash all transactions immediately in `create_self_transfer` in order to get the txid (before we relied on the result of `testmempoolaccept`).

  On my machine, this decreases the execution time quite noticably:

  master branch:
  ```
  $ time ./test/functional/feature_fee_estimation.py
  real    3m20.771s
  user    2m52.360s
  sys     0m39.340s
  ```

  PR branch:
  ```
  $ time ./test/functional/feature_fee_estimation.py
  real    2m1.386s
  user    1m42.510s
  sys     0m22.980s
  ```

  Partly fixes #24828 (hopefully).

ACKs for top commit:
  danielabrozzoni:
    tACK a498acce4514d83d8dafcebaad522a89b6dc70fa

Tree-SHA512: f20c358ba42b2ded86175f46ff3ff9eaefb84175cbd1c2624f44904c8d8888e67ce64d6dcbb26aabbf07906e6f5bdea40353eba9ae668618cadcfc517ef7201b

1 files changed, 7 insertions, 4 deletions

diff --git a/test/functional/test_framework/wallet.py b/test/functional/test_framework/wallet.py
index e86f365f11..6901bcfe66 100644
--- a/test/functional/test_framework/wallet.py
+++ b/test/functional/test_framework/wallet.py
@@ -127,6 +127,7 @@ class MiniWallet:
             if not fixed_length:
                 break
         tx.vin[0].scriptSig = CScript([der_sig + bytes(bytearray([SIGHASH_ALL]))])
+        tx.rehash()
 
     def generate(self, num_blocks, **kwargs):
         """Generate blocks with coinbase outputs to the internal address, and append the outputs to the internal list"""
@@ -233,7 +234,8 @@ class MiniWallet:
         return tx
 
     def create_self_transfer(self, *, fee_rate=Decimal("0.003"), from_node=None, utxo_to_spend=None, mempool_valid=True, locktime=0, sequence=0):
-        """Create and return a tx with the specified fee_rate. Fee may be exact or at most one satoshi higher than needed."""
+        """Create and return a tx with the specified fee_rate. Fee may be exact or at most one satoshi higher than needed.
+           Checking mempool validity via the testmempoolaccept RPC can be skipped by setting mempool_valid to False."""
         from_node = from_node or self._test_node
         utxo_to_spend = utxo_to_spend or self.get_utxo()
         if self._priv_key is None:
@@ -260,12 +262,13 @@ class MiniWallet:
             tx.wit.vtxinwit[0].scriptWitness.stack = [CScript([OP_TRUE]), bytes([LEAF_VERSION_TAPSCRIPT]) + self._internal_key]
         tx_hex = tx.serialize().hex()
 
-        tx_info = from_node.testmempoolaccept([tx_hex])[0]
-        assert_equal(mempool_valid, tx_info['allowed'])
         if mempool_valid:
+            tx_info = from_node.testmempoolaccept([tx_hex])[0]
+            assert_equal(tx_info['allowed'], True)
             assert_equal(tx_info['vsize'], vsize)
             assert_equal(tx_info['fees']['base'], utxo_to_spend['value'] - Decimal(send_value) / COIN)
-        return {'txid': tx_info['txid'], 'wtxid': tx_info['wtxid'], 'hex': tx_hex, 'tx': tx}
+
+        return {'txid': tx.rehash(), 'wtxid': tx.getwtxid(), 'hex': tx_hex, 'tx': tx}
 
     def sendrawtransaction(self, *, from_node, tx_hex, **kwargs):
         txid = from_node.sendrawtransaction(hexstring=tx_hex, **kwargs)