test: change low fee parents to 0-fee

The test is harder to read, and had an explicit 1sat/vbyte
floor assumption in a single place which is incorrect. Using
0-fee makes the test more future proof.

test/functional/p2p_1p1c_network.py

@@ -10,11 +10,9 @@ too-low-feerate transactions). The packages should be received and accepted by a
 """
 
 from decimal import Decimal
-from math import ceil
 
 from test_framework.mempool_util import (
     DEFAULT_MIN_RELAY_TX_FEE,
-    fill_mempool,
 )
 from test_framework.messages import (
     COIN,
@@ -26,7 +24,6 @@ from test_framework.p2p import (
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
-    assert_greater_than,
 )
 from test_framework.wallet import (
     MiniWallet,
@@ -39,20 +36,9 @@ class PackageRelayTest(BitcoinTestFramework):
         self.num_nodes = 4
         # hugely speeds up the test, as it involves multiple hops of tx relay.
         self.noban_tx_relay = True
-        self.extra_args = [[
-            "-maxmempool=5",
-        ]] * self.num_nodes
-
-    def raise_network_minfee(self):
-        fill_mempool(self, self.nodes[0])
-
-        self.log.debug("Check that all nodes' mempool minimum feerates are above min relay feerate")
-        for node in self.nodes:
-            assert_equal(node.getmempoolinfo()['minrelaytxfee'], Decimal(DEFAULT_MIN_RELAY_TX_FEE) / COIN)
-            assert_greater_than(node.getmempoolinfo()['mempoolminfee'], Decimal(DEFAULT_MIN_RELAY_TX_FEE) / COIN)
 
     def create_basic_1p1c(self, wallet):
-        low_fee_parent = wallet.create_self_transfer(fee_rate=Decimal(DEFAULT_MIN_RELAY_TX_FEE) / COIN, confirmed_only=True)
+        low_fee_parent = wallet.create_self_transfer(fee_rate=0, confirmed_only=True)
         high_fee_child = wallet.create_self_transfer(utxo_to_spend=low_fee_parent["new_utxo"], fee_rate=999*Decimal(DEFAULT_MIN_RELAY_TX_FEE)/ COIN)
         package_hex_basic = [low_fee_parent["hex"], high_fee_child["hex"]]
         return package_hex_basic, low_fee_parent["tx"], high_fee_child["tx"]
@@ -61,25 +47,16 @@ class PackageRelayTest(BitcoinTestFramework):
         # First create a tester tx to see the vsize, and then adjust the fees
         utxo_for_2outs = wallet.get_utxo(confirmed_only=True)
 
-        low_fee_parent_2outs_tester = wallet.create_self_transfer_multi(
-            utxos_to_spend=[utxo_for_2outs],
-            num_outputs=2,
-        )
-
-        # Target 1sat/vB so the number of satoshis is equal to the vsize.
-        # Round up. The goal is to be between min relay feerate and mempool min feerate.
-        fee_2outs = ceil(low_fee_parent_2outs_tester["tx"].get_vsize() / 2)
-
         low_fee_parent_2outs = wallet.create_self_transfer_multi(
             utxos_to_spend=[utxo_for_2outs],
             num_outputs=2,
-            fee_per_output=fee_2outs,
+            fee_per_output=0,
         )
 
         # Now create the child
         high_fee_child_2outs = wallet.create_self_transfer_multi(
             utxos_to_spend=low_fee_parent_2outs["new_utxos"][::-1],
-            fee_per_output=fee_2outs*100,
+            fee_per_output=10_000,
         )
         return [low_fee_parent_2outs["hex"], high_fee_child_2outs["hex"]], low_fee_parent_2outs["tx"], high_fee_child_2outs["tx"]
 
@@ -93,7 +70,7 @@ class PackageRelayTest(BitcoinTestFramework):
         return [parent1["hex"], parent2["hex"], child["hex"]], parent1["tx"], parent2["tx"], child["tx"]
 
     def create_packages(self):
-        # 1: Basic 1-parent-1-child package, parent 1sat/vB, child 999sat/vB
+        # 1: Basic 1-parent-1-child package, parent 0sat/vB, child 999sat/vB
         package_hex_1, parent_1, child_1 = self.create_basic_1p1c(self.wallet)
 
         # 2: same as 1, parent's txid is the same as its wtxid.
@@ -127,9 +104,6 @@ class PackageRelayTest(BitcoinTestFramework):
         self.generate(self.wallet_nonsegwit, 10)
         self.generate(self.wallet, 120)
 
-        self.log.info("Fill mempools with large transactions to raise mempool minimum feerates")
-        self.raise_network_minfee()
-
         # Create the transactions.
         self.wallet.rescan_utxos(include_mempool=True)
         packages_to_submit, transactions_to_presend = self.create_packages()