test: Add mempool fee histogram test coverage

Original commit: bitcoin@0b6ba66

Co-authored-by: João Barbosa <[email protected]>
Co-authored-by: Jon Atack <[email protected]>

Github-Pull: bitcoin#21422
Rebased-From: c5e53d0

Author: kiminuo

test/functional/mempool_fee_histogram.py

@@ -0,0 +1,164 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023 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 fee histogram."""
+
+from decimal import Decimal
+
+from test_framework.blocktools import COINBASE_MATURITY
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_greater_than,
+    assert_greater_than_or_equal,
+)
+
+class MempoolFeeHistogramTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser)
+
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        node = self.nodes[0]
+        self.generate(self.nodes[0], COINBASE_MATURITY + 2, sync_fun=self.no_op)
+
+        # We have two UTXOs (utxo_1 and utxo_2) and we create three changeless transactions:
+        # - tx1 (5 sat/vB): spending utxo_1
+        # - tx2 (14 sat/vB): spending output from tx1
+        # - tx3 (6 sat/vB): spending utxo_2 and the output from tx2
+
+        self.log.info("Test getmempoolinfo does not return fee histogram by default")
+        assert ("fee_histogram" not in node.getmempoolinfo())
+
+        self.log.info("Test getmempoolinfo returns empty fee histogram when mempool is empty")
+        info = node.getmempoolinfo([1, 2, 3])
+
+        (non_empty_groups, empty_groups, total_fees) = self.histogram_stats(info['fee_histogram'])
+        assert_equal(0, non_empty_groups)
+        assert_equal(3, empty_groups)
+        assert_equal(0, total_fees)
+
+        for i in ['1', '2', '3']:
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['size'])
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['count'])
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['fees'])
+            assert_equal(int(i), info['fee_histogram']['fee_rate_groups'][i]['from'])
+
+        self.log.info("Test that we have two spendable UTXOs and lock the second one")
+        utxos = node.listunspent()
+        assert_equal(2, len(utxos))
+        node.lockunspent(False, [{"txid": utxos[1]["txid"], "vout": utxos[1]["vout"]}])
+
+        self.log.info("Send tx1 transaction with 5 sat/vB fee rate")
+        node.sendtoaddress(address=node.getnewaddress(), amount=Decimal("50.0"), fee_rate=5, subtractfeefromamount=True)
+
+        self.log.info("Test fee rate histogram when mempool contains 1 transaction (tx1: 5 sat/vB)")
+        info = node.getmempoolinfo([1, 3, 5, 10])
+        (non_empty_groups, empty_groups, total_fees) = self.histogram_stats(info['fee_histogram'])
+        assert_equal(1, non_empty_groups)
+        assert_equal(3, empty_groups)
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['5']['count'])
+        assert_equal(total_fees, info['fee_histogram']['total_fees'])
+
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['1']['size'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['1']['count'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['1']['fees'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['1']['from'])
+
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['3']['size'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['3']['count'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['3']['fees'])
+        assert_equal(3, info['fee_histogram']['fee_rate_groups']['3']['from'])
+
+        assert_equal(188, info['fee_histogram']['fee_rate_groups']['5']['size'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['5']['count'])
+        assert_equal(940, info['fee_histogram']['fee_rate_groups']['5']['fees'])
+        assert_equal(5, info['fee_histogram']['fee_rate_groups']['5']['from'])
+
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['10']['size'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['10']['count'])
+        assert_equal(0, info['fee_histogram']['fee_rate_groups']['10']['fees'])
+        assert_equal(10, info['fee_histogram']['fee_rate_groups']['10']['from'])
+
+        self.log.info("Send tx2 transaction with 14 sat/vB fee rate (spends tx1 UTXO)")
+        node.sendtoaddress(address=node.getnewaddress(), amount=Decimal("25.0"), fee_rate=14, subtractfeefromamount=True)
+
+        self.log.info("Test fee rate histogram when mempool contains 2 transactions (tx1: 5 sat/vB, tx2: 14 sat/vB)")
+        info = node.getmempoolinfo([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
+
+        # Verify that tx1 and tx2 are reported in 5 sat/vB and 14 sat/vB in fee rate groups respectively
+        (non_empty_groups, empty_groups, total_fees) = self.histogram_stats(info['fee_histogram'])
+        assert_equal(2, non_empty_groups)
+        assert_equal(13, empty_groups)
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['5']['count'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['14']['count'])
+        assert_equal(total_fees, info['fee_histogram']['total_fees'])
+
+        # Unlock the second UTXO which we locked
+        node.lockunspent(True, [{"txid": utxos[1]["txid"], "vout": utxos[1]["vout"]}])
+
+        self.log.info("Send tx3 transaction with 6 sat/vB fee rate (spends all available UTXOs)")
+        node.sendtoaddress(address=node.getnewaddress(), amount=Decimal("99.9"), fee_rate=6, subtractfeefromamount=True)
+
+        self.log.info("Test fee rate histogram when mempool contains 3 transactions (tx1: 5 sat/vB, tx2: 14 sat/vB, tx3: 6 sat/vB)")
+        info = node.getmempoolinfo([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
+
+        # Verify that each of 5, 6 and 14 sat/vB fee rate groups contain one transaction
+        (non_empty_groups, empty_groups, total_fees) = self.histogram_stats(info['fee_histogram'])
+        assert_equal(3, non_empty_groups)
+        assert_equal(12, empty_groups)
+
+        for i in ['1', '2', '3', '4', '7', '8', '9', '10', '11', '12', '13', '15']:
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['size'])
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['count'])
+            assert_equal(0, info['fee_histogram']['fee_rate_groups'][i]['fees'])
+            assert_equal(int(i), info['fee_histogram']['fee_rate_groups'][i]['from'])
+
+        assert_equal(188, info['fee_histogram']['fee_rate_groups']['5']['size'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['5']['count'])
+        assert_equal(940, info['fee_histogram']['fee_rate_groups']['5']['fees'])
+        assert_equal(5, info['fee_histogram']['fee_rate_groups']['5']['from'])
+
+        assert_equal(356, info['fee_histogram']['fee_rate_groups']['6']['size'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['6']['count'])
+        assert_equal(2136, info['fee_histogram']['fee_rate_groups']['6']['fees'])
+        assert_equal(6, info['fee_histogram']['fee_rate_groups']['6']['from'])
+
+        assert_equal(141, info['fee_histogram']['fee_rate_groups']['14']['size'])
+        assert_equal(1, info['fee_histogram']['fee_rate_groups']['14']['count'])
+        assert_equal(1974, info['fee_histogram']['fee_rate_groups']['14']['fees'])
+        assert_equal(14, info['fee_histogram']['fee_rate_groups']['14']['from'])
+
+        assert_equal(total_fees, info['fee_histogram']['total_fees'])
+
+    def histogram_stats(self, histogram):
+        total_fees = 0
+        empty_count = 0
+        non_empty_count = 0
+
+        for key, bin in histogram['fee_rate_groups'].items():
+            assert_equal(int(key), bin['from'])
+            if bin['fees'] > 0:
+                assert_greater_than(bin['count'], 0)
+            else:
+                assert_equal(bin['count'], 0)
+            assert_greater_than_or_equal(bin['fees'], 0)
+            assert_greater_than_or_equal(bin['size'], 0)
+            total_fees += bin['fees']
+
+            if bin['count'] == 0:
+                empty_count += 1
+            else:
+                non_empty_count += 1
+
+        return (non_empty_count, empty_count, total_fees)
+
+if __name__ == '__main__':
+    MempoolFeeHistogramTest(__file__).main()

test/functional/test_runner.py

@@ -304,6 +304,7 @@
     'p2p_initial_headers_sync.py',
     'feature_nulldummy.py',
     'mempool_accept.py',
+    'mempool_fee_histogram.py',
     'mempool_expiry.py',
     'wallet_import_with_label.py --legacy-wallet',
     'wallet_importdescriptors.py --descriptors',