Merge #19153: test: mempool compatibility test

16d4b3fd6d5aad18ebb731a5006a15180d3661ef test: mempool.dat compatibility between versions (Ivan Metlushko)

Pull request description:

  Rationale: Verify mempool.dat compatibility between versions

  The format of mempool.dat has been changed in #18038
  The tests verifies the fix made in #18807 and ensures that the file format is compatible between current version and v0.19.1
  The test verifies both backward and forward compatibility.

  This PR also adds a log when we fail to add a tx loaded from mempool.dat.
  It was useful when debugging this test and could be potentially useful to debug other scenarios as well.

  Closes #19037

ACKs for top commit:
  Sjors:
    tACK 16d4b3fd6d5aad18ebb731a5006a15180d3661ef

Tree-SHA512: 00a38bf528c6478cb0da467af216488f83c1e3ca4d9166c109202ea8284023e99d87a3d6e252c4d88d08d9b5ed1a730b3e1970d6e5c0aef526fa7ced40de7490

2 files changed, 79 insertions, 0 deletions

diff --git a/test/functional/mempool_compatibility.py b/test/functional/mempool_compatibility.py
new file mode 100755
index 0000000000..eb2fee11ae
--- /dev/null
+++ b/test/functional/mempool_compatibility.py
@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017-2020 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 that mempool.dat is both backward and forward compatible between versions
+
+NOTE: The test is designed to prevent cases when compatibility is broken accidentally.
+In case we need to break mempool compatibility we can continue to use the test by just bumping the version number.
+
+Download node binaries:
+contrib/devtools/previous_release.sh -b v0.19.1 v0.18.1 v0.17.1 v0.16.3 v0.15.2
+
+Only v0.15.2 is required by this test. The rest is used in other backwards compatibility tests.
+"""
+
+import os
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    adjust_bitcoin_conf_for_pre_17
+)
+
+class MempoolCompatibilityTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 2
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+        self.skip_if_no_previous_releases()
+
+    def setup_network(self):
+        self.add_nodes(self.num_nodes, versions=[
+            150200, # oldest version supported by the test framework
+            None,
+        ])
+        adjust_bitcoin_conf_for_pre_17(self.nodes[0].bitcoinconf)
+        self.start_nodes()
+        self.import_deterministic_coinbase_privkeys()
+
+    def run_test(self):
+        self.log.info("Test that mempool.dat is compatible between versions")
+
+        old_node = self.nodes[0]
+        new_node = self.nodes[1]
+        recipient = old_node.getnewaddress()
+        self.stop_node(1)
+
+        self.log.info("Add a transaction to mempool on old node and shutdown")
+        old_tx_hash = old_node.sendtoaddress(recipient, 0.0001)
+        assert old_tx_hash in old_node.getrawmempool()
+        self.stop_node(0)
+
+        self.log.info("Move mempool.dat from old to new node")
+        old_node_mempool = os.path.join(old_node.datadir, self.chain, 'mempool.dat')
+        new_node_mempool = os.path.join(new_node.datadir, self.chain, 'mempool.dat')
+        os.rename(old_node_mempool, new_node_mempool)
+
+        self.log.info("Start new node and verify mempool contains the tx")
+        self.start_node(1)
+        assert old_tx_hash in new_node.getrawmempool()
+
+        self.log.info("Add unbroadcasted tx to mempool on new node and shutdown")
+        unbroadcasted_tx_hash = new_node.sendtoaddress(recipient, 0.0001)
+        assert unbroadcasted_tx_hash in new_node.getrawmempool()
+        mempool = new_node.getrawmempool(True)
+        assert mempool[unbroadcasted_tx_hash]['unbroadcast']
+        self.stop_node(1)
+
+        self.log.info("Move mempool.dat from new to old node")
+        os.rename(new_node_mempool, old_node_mempool)
+
+        self.log.info("Start old node again and verify mempool contains both txs")
+        self.start_node(0, ['-nowallet'])
+        assert old_tx_hash in old_node.getrawmempool()
+        assert unbroadcasted_tx_hash in old_node.getrawmempool()
+
+if __name__ == "__main__":
+    MempoolCompatibilityTest().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 8b11dc8376..79a172706c 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -233,6 +233,7 @@ BASE_SCRIPTS = [
     'feature_includeconf.py',
     'feature_asmap.py',
     'mempool_unbroadcast.py',
+    'mempool_compatibility.py',
     'rpc_deriveaddresses.py',
     'rpc_deriveaddresses.py --usecli',
     'rpc_scantxoutset.py',