17 files changed, 397 insertions, 44 deletions

diff --git a/test/functional/feature_backwards_compatibility.py b/test/functional/feature_backwards_compatibility.py
index 9cff79a42c..596ff206f2 100755
--- a/test/functional/feature_backwards_compatibility.py
+++ b/test/functional/feature_backwards_compatibility.py
@@ -6,7 +6,11 @@
 
 Test various backwards compatibility scenarios. Download the previous node binaries:
 
-contrib/devtools/previous_release.sh -b v0.19.0.1 v0.18.1 v0.17.1
+contrib/devtools/previous_release.sh -b v0.19.1 v0.18.1 v0.17.1 v0.16.3 v0.15.2
+
+v0.15.2 is not required by this test, but it is used in wallet_upgradewallet.py.
+Due to a hardfork in regtest, it can't be used to sync nodes.
+
 
 Due to RPC changes introduced in various versions the below tests
 won't work for older versions without some patches or workarounds.
@@ -22,6 +26,7 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.descriptors import descsum_create
 
 from test_framework.util import (
+    adjust_bitcoin_conf_for_pre_17,
     assert_equal,
     sync_blocks,
     sync_mempools,
@@ -31,14 +36,15 @@ from test_framework.util import (
 class BackwardsCompatibilityTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
-        self.num_nodes = 5
+        self.num_nodes = 6
         # Add new version after each release:
         self.extra_args = [
             ["-addresstype=bech32"], # Pre-release: use to mine blocks
             ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # Pre-release: use to receive coins, swap wallets, etc
-            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # v0.19.0.1
+            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # v0.19.1
             ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # v0.18.1
-            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"] # v0.17.1
+            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # v0.17.1
+            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"], # v0.16.3
         ]
 
     def skip_test_if_missing_module(self):
@@ -49,10 +55,13 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         self.add_nodes(self.num_nodes, extra_args=self.extra_args, versions=[
             None,
             None,
-            190001,
+            190100,
             180100,
             170100,
+            160300,
         ])
+        # adapt bitcoin.conf, because older bitcoind's don't recognize config sections
+        adjust_bitcoin_conf_for_pre_17(self.nodes[5].bitcoinconf)
 
         self.start_nodes()
 
@@ -65,10 +74,11 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         res = self.nodes[self.num_nodes - 1].getblockchaininfo()
         assert_equal(res['blocks'], 101)
 
-        node_master = self.nodes[self.num_nodes - 4]
-        node_v19 = self.nodes[self.num_nodes - 3]
-        node_v18 = self.nodes[self.num_nodes - 2]
-        node_v17 = self.nodes[self.num_nodes - 1]
+        node_master = self.nodes[self.num_nodes - 5]
+        node_v19 = self.nodes[self.num_nodes - 4]
+        node_v18 = self.nodes[self.num_nodes - 3]
+        node_v17 = self.nodes[self.num_nodes - 2]
+        node_v16 = self.nodes[self.num_nodes - 1]
 
         self.log.info("Test wallet backwards compatibility...")
         # Create a number of wallets and open them in older versions:
@@ -167,6 +177,7 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         node_v19_wallets_dir = os.path.join(node_v19.datadir, "regtest/wallets")
         node_v18_wallets_dir = os.path.join(node_v18.datadir, "regtest/wallets")
         node_v17_wallets_dir = os.path.join(node_v17.datadir, "regtest/wallets")
+        node_v16_wallets_dir = os.path.join(node_v16.datadir, "regtest")
         node_master.unloadwallet("w1")
         node_master.unloadwallet("w2")
         node_v19.unloadwallet("w1_v19")
@@ -174,6 +185,13 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         node_v18.unloadwallet("w1_v18")
         node_v18.unloadwallet("w2_v18")
 
+        # Copy wallets to v0.16
+        for wallet in os.listdir(node_master_wallets_dir):
+            shutil.copytree(
+                os.path.join(node_master_wallets_dir, wallet),
+                os.path.join(node_v16_wallets_dir, wallet)
+            )
+
         # Copy wallets to v0.17
         for wallet in os.listdir(node_master_wallets_dir):
             shutil.copytree(
@@ -292,10 +310,17 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         # assert_raises_rpc_error(-4, "Wallet loading failed.", node_v17.loadwallet, 'w3_v18')
 
         # Instead, we stop node and try to launch it with the wallet:
-        self.stop_node(self.num_nodes - 1)
+        self.stop_node(4)
         node_v17.assert_start_raises_init_error(["-wallet=w3_v18"], "Error: Error loading w3_v18: Wallet requires newer version of Bitcoin Core")
         node_v17.assert_start_raises_init_error(["-wallet=w3"], "Error: Error loading w3: Wallet requires newer version of Bitcoin Core")
-        self.start_node(self.num_nodes - 1)
+        self.start_node(4)
+
+        # Open most recent wallet in v0.16 (no loadwallet RPC)
+        self.stop_node(5)
+        self.start_node(5, extra_args=["-wallet=w2"])
+        wallet = node_v16.get_wallet_rpc("w2")
+        info = wallet.getwalletinfo()
+        assert info['keypoolsize'] == 1
 
         self.log.info("Test wallet upgrade path...")
         # u1: regular wallet, created with v0.17
diff --git a/test/functional/feature_loadblock.py b/test/functional/feature_loadblock.py
index 1138b0f0ea..82f1331685 100755
--- a/test/functional/feature_loadblock.py
+++ b/test/functional/feature_loadblock.py
@@ -16,10 +16,8 @@ import sys
 import tempfile
 import urllib
 
-from test_framework.test_framework import (
-    BitcoinTestFramework,
-)
-from test_framework.util import assert_equal, wait_until
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
 
 
 class LoadblockTest(BitcoinTestFramework):
@@ -75,7 +73,7 @@ class LoadblockTest(BitcoinTestFramework):
         self.log.info("Restart second, unsynced node with bootstrap file")
         self.stop_node(1)
         self.start_node(1, ["-loadblock=" + bootstrap_file])
-        wait_until(lambda: self.nodes[1].getblockcount() == 100)
+        assert_equal(self.nodes[1].getblockcount(), 100)  # start_node is blocking on all block files being imported
 
         assert_equal(self.nodes[1].getblockchaininfo()['blocks'], 100)
         assert_equal(self.nodes[0].getbestblockhash(), self.nodes[1].getbestblockhash())
diff --git a/test/functional/feature_notifications.py b/test/functional/feature_notifications.py
index b110a559c0..47200b6cc6 100755
--- a/test/functional/feature_notifications.py
+++ b/test/functional/feature_notifications.py
@@ -5,12 +5,14 @@
 """Test the -alertnotify, -blocknotify and -walletnotify options."""
 import os
 
-from test_framework.address import ADDRESS_BCRT1_UNSPENDABLE
+from test_framework.address import ADDRESS_BCRT1_UNSPENDABLE, keyhash_to_p2pkh
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
     wait_until,
     connect_nodes,
+    disconnect_nodes,
+    hex_str_to_bytes,
 )
 
 # Linux allow all characters other than \x00
@@ -81,8 +83,72 @@ class NotificationsTest(BitcoinTestFramework):
             # directory content should equal the generated transaction hashes
             txids_rpc = list(map(lambda t: notify_outputname(self.wallet, t['txid']), self.nodes[1].listtransactions("*", block_count)))
             assert_equal(sorted(txids_rpc), sorted(os.listdir(self.walletnotify_dir)))
+            for tx_file in os.listdir(self.walletnotify_dir):
+                os.remove(os.path.join(self.walletnotify_dir, tx_file))
+
+            # Conflicting transactions tests. Give node 0 same wallet seed as
+            # node 1, generate spends from node 0, and check notifications
+            # triggered by node 1
+            self.log.info("test -walletnotify with conflicting transactions")
+            self.nodes[0].sethdseed(seed=self.nodes[1].dumpprivkey(keyhash_to_p2pkh(hex_str_to_bytes(self.nodes[1].getwalletinfo()['hdseedid'])[::-1])))
+            self.nodes[0].rescanblockchain()
+            self.nodes[0].generatetoaddress(100, ADDRESS_BCRT1_UNSPENDABLE)
+
+            # Generate transaction on node 0, sync mempools, and check for
+            # notification on node 1.
+            tx1 = self.nodes[0].sendtoaddress(address=ADDRESS_BCRT1_UNSPENDABLE, amount=1, replaceable=True)
+            assert_equal(tx1 in self.nodes[0].getrawmempool(), True)
+            self.sync_mempools()
+            self.expect_wallet_notify([tx1])
+
+            # Generate bump transaction, sync mempools, and check for bump1
+            # notification. In the future, per
+            # https://github.com/bitcoin/bitcoin/pull/9371, it might be better
+            # to have notifications for both tx1 and bump1.
+            bump1 = self.nodes[0].bumpfee(tx1)["txid"]
+            assert_equal(bump1 in self.nodes[0].getrawmempool(), True)
+            self.sync_mempools()
+            self.expect_wallet_notify([bump1])
+
+            # Add bump1 transaction to new block, checking for a notification
+            # and the correct number of confirmations.
+            self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
+            self.sync_blocks()
+            self.expect_wallet_notify([bump1])
+            assert_equal(self.nodes[1].gettransaction(bump1)["confirmations"], 1)
+
+            # Generate a second transaction to be bumped.
+            tx2 = self.nodes[0].sendtoaddress(address=ADDRESS_BCRT1_UNSPENDABLE, amount=1, replaceable=True)
+            assert_equal(tx2 in self.nodes[0].getrawmempool(), True)
+            self.sync_mempools()
+            self.expect_wallet_notify([tx2])
+
+            # Bump tx2 as bump2 and generate a block on node 0 while
+            # disconnected, then reconnect and check for notifications on node 1
+            # about newly confirmed bump2 and newly conflicted tx2. Currently
+            # only the bump2 notification is sent. Ideally, notifications would
+            # be sent both for bump2 and tx2, which was the previous behavior
+            # before being broken by an accidental change in PR
+            # https://github.com/bitcoin/bitcoin/pull/16624. The bug is reported
+            # in issue https://github.com/bitcoin/bitcoin/issues/18325.
+            disconnect_nodes(self.nodes[0], 1)
+            bump2 = self.nodes[0].bumpfee(tx2)["txid"]
+            self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
+            assert_equal(self.nodes[0].gettransaction(bump2)["confirmations"], 1)
+            assert_equal(tx2 in self.nodes[1].getrawmempool(), True)
+            connect_nodes(self.nodes[0], 1)
+            self.sync_blocks()
+            self.expect_wallet_notify([bump2])
+            assert_equal(self.nodes[1].gettransaction(bump2)["confirmations"], 1)
 
         # TODO: add test for `-alertnotify` large fork notifications
 
+    def expect_wallet_notify(self, tx_ids):
+        wait_until(lambda: len(os.listdir(self.walletnotify_dir)) >= len(tx_ids), timeout=10)
+        assert_equal(sorted(notify_outputname(self.wallet, tx_id) for tx_id in tx_ids), sorted(os.listdir(self.walletnotify_dir)))
+        for tx_file in os.listdir(self.walletnotify_dir):
+            os.remove(os.path.join(self.walletnotify_dir, tx_file))
+
+
 if __name__ == '__main__':
     NotificationsTest().main()
diff --git a/test/functional/feature_reindex.py b/test/functional/feature_reindex.py
index 940b403f9c..31cea8d1b7 100755
--- a/test/functional/feature_reindex.py
+++ b/test/functional/feature_reindex.py
@@ -10,10 +10,10 @@
 """
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import wait_until
+from test_framework.util import assert_equal
 
-class ReindexTest(BitcoinTestFramework):
 
+class ReindexTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1
@@ -24,7 +24,7 @@ class ReindexTest(BitcoinTestFramework):
         self.stop_nodes()
         extra_args = [["-reindex-chainstate" if justchainstate else "-reindex"]]
         self.start_nodes(extra_args)
-        wait_until(lambda: self.nodes[0].getblockcount() == blockcount)
+        assert_equal(self.nodes[0].getblockcount(), blockcount)  # start_node is blocking on reindex
         self.log.info("Success")
 
     def run_test(self):
diff --git a/test/functional/mempool_persist.py b/test/functional/mempool_persist.py
index 99003d2d1f..3969da2eb0 100755
--- a/test/functional/mempool_persist.py
+++ b/test/functional/mempool_persist.py
@@ -95,8 +95,8 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.start_node(1, extra_args=["-persistmempool=0"])
         self.start_node(0)
         self.start_node(2)
-        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"], timeout=1)
-        wait_until(lambda: self.nodes[2].getmempoolinfo()["loaded"], timeout=1)
+        assert self.nodes[0].getmempoolinfo()["loaded"]  # start_node is blocking on the mempool being loaded
+        assert self.nodes[2].getmempoolinfo()["loaded"]
         assert_equal(len(self.nodes[0].getrawmempool()), 6)
         assert_equal(len(self.nodes[2].getrawmempool()), 5)
         # The others have loaded their mempool. If node_1 loaded anything, we'd probably notice by now:
@@ -117,13 +117,13 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.log.debug("Stop-start node0 with -persistmempool=0. Verify that it doesn't load its mempool.dat file.")
         self.stop_nodes()
         self.start_node(0, extra_args=["-persistmempool=0", "-disablewallet"])
-        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
+        assert self.nodes[0].getmempoolinfo()["loaded"]
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
 
         self.log.debug("Stop-start node0. Verify that it has the transactions in its mempool.")
         self.stop_nodes()
         self.start_node(0)
-        wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
+        assert self.nodes[0].getmempoolinfo()["loaded"]
         assert_equal(len(self.nodes[0].getrawmempool()), 6)
 
         mempooldat0 = os.path.join(self.nodes[0].datadir, self.chain, 'mempool.dat')
@@ -137,7 +137,7 @@ class MempoolPersistTest(BitcoinTestFramework):
         os.rename(mempooldat0, mempooldat1)
         self.stop_nodes()
         self.start_node(1, extra_args=[])
-        wait_until(lambda: self.nodes[1].getmempoolinfo()["loaded"])
+        assert self.nodes[1].getmempoolinfo()["loaded"]
         assert_equal(len(self.nodes[1].getrawmempool()), 6)
 
         self.log.debug("Prevent bitcoind from writing mempool.dat to disk. Verify that `savemempool` fails")
diff --git a/test/functional/p2p_blockfilters.py b/test/functional/p2p_blockfilters.py
new file mode 100755
index 0000000000..4d00a6dc07
--- /dev/null
+++ b/test/functional/p2p_blockfilters.py
@@ -0,0 +1,134 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Tests NODE_COMPACT_FILTERS (BIP 157/158).
+
+Tests that a node configured with -blockfilterindex and -peerblockfilters can serve
+cfcheckpts.
+"""
+
+from test_framework.messages import (
+    FILTER_TYPE_BASIC,
+    msg_getcfcheckpt,
+)
+from test_framework.mininode import P2PInterface
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    connect_nodes,
+    disconnect_nodes,
+    wait_until,
+)
+
+class CompactFiltersTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.rpc_timeout = 480
+        self.num_nodes = 2
+        self.extra_args = [
+            ["-blockfilterindex", "-peerblockfilters"],
+            ["-blockfilterindex"],
+        ]
+
+    def run_test(self):
+        # Node 0 supports COMPACT_FILTERS, node 1 does not.
+        node0 = self.nodes[0].add_p2p_connection(P2PInterface())
+        node1 = self.nodes[1].add_p2p_connection(P2PInterface())
+
+        # Nodes 0 & 1 share the same first 999 blocks in the chain.
+        self.nodes[0].generate(999)
+        self.sync_blocks(timeout=600)
+
+        # Stale blocks by disconnecting nodes 0 & 1, mining, then reconnecting
+        disconnect_nodes(self.nodes[0], 1)
+
+        self.nodes[0].generate(1)
+        wait_until(lambda: self.nodes[0].getblockcount() == 1000)
+        stale_block_hash = self.nodes[0].getblockhash(1000)
+
+        self.nodes[1].generate(1001)
+        wait_until(lambda: self.nodes[1].getblockcount() == 2000)
+
+        self.log.info("get cfcheckpt on chain to be re-orged out.")
+        request = msg_getcfcheckpt(
+            filter_type=FILTER_TYPE_BASIC,
+            stop_hash=int(stale_block_hash, 16)
+        )
+        node0.send_and_ping(message=request)
+        response = node0.last_message['cfcheckpt']
+        assert_equal(response.filter_type, request.filter_type)
+        assert_equal(response.stop_hash, request.stop_hash)
+        assert_equal(len(response.headers), 1)
+
+        self.log.info("Reorg node 0 to a new chain.")
+        connect_nodes(self.nodes[0], 1)
+        self.sync_blocks(timeout=600)
+
+        main_block_hash = self.nodes[0].getblockhash(1000)
+        assert main_block_hash != stale_block_hash, "node 0 chain did not reorganize"
+
+        self.log.info("Check that peers can fetch cfcheckpt on active chain.")
+        tip_hash = self.nodes[0].getbestblockhash()
+        request = msg_getcfcheckpt(
+            filter_type=FILTER_TYPE_BASIC,
+            stop_hash=int(tip_hash, 16)
+        )
+        node0.send_and_ping(request)
+        response = node0.last_message['cfcheckpt']
+        assert_equal(response.filter_type, request.filter_type)
+        assert_equal(response.stop_hash, request.stop_hash)
+
+        main_cfcheckpt = self.nodes[0].getblockfilter(main_block_hash, 'basic')['header']
+        tip_cfcheckpt = self.nodes[0].getblockfilter(tip_hash, 'basic')['header']
+        assert_equal(
+            response.headers,
+            [int(header, 16) for header in (main_cfcheckpt, tip_cfcheckpt)]
+        )
+
+        self.log.info("Check that peers can fetch cfcheckpt on stale chain.")
+        request = msg_getcfcheckpt(
+            filter_type=FILTER_TYPE_BASIC,
+            stop_hash=int(stale_block_hash, 16)
+        )
+        node0.send_and_ping(request)
+        response = node0.last_message['cfcheckpt']
+
+        stale_cfcheckpt = self.nodes[0].getblockfilter(stale_block_hash, 'basic')['header']
+        assert_equal(
+            response.headers,
+            [int(header, 16) for header in (stale_cfcheckpt,)]
+        )
+
+        self.log.info("Requests to node 1 without NODE_COMPACT_FILTERS results in disconnection.")
+        requests = [
+            msg_getcfcheckpt(
+                filter_type=FILTER_TYPE_BASIC,
+                stop_hash=int(main_block_hash, 16)
+            ),
+        ]
+        for request in requests:
+            node1 = self.nodes[1].add_p2p_connection(P2PInterface())
+            node1.send_message(request)
+            node1.wait_for_disconnect()
+
+        self.log.info("Check that invalid requests result in disconnection.")
+        requests = [
+            # Requesting unknown filter type results in disconnection.
+            msg_getcfcheckpt(
+                filter_type=255,
+                stop_hash=int(main_block_hash, 16)
+            ),
+            # Requesting unknown hash results in disconnection.
+            msg_getcfcheckpt(
+                filter_type=FILTER_TYPE_BASIC,
+                stop_hash=123456789,
+            ),
+        ]
+        for request in requests:
+            node0 = self.nodes[0].add_p2p_connection(P2PInterface())
+            node0.send_message(request)
+            node0.wait_for_disconnect()
+
+if __name__ == '__main__':
+    CompactFiltersTest().main()
diff --git a/test/functional/p2p_getdata.py b/test/functional/p2p_getdata.py
new file mode 100755
index 0000000000..fd94a09d80
--- /dev/null
+++ b/test/functional/p2p_getdata.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+# Copyright (c) 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 GETDATA processing behavior"""
+from collections import defaultdict
+
+from test_framework.messages import (
+    CInv,
+    msg_getdata,
+)
+from test_framework.mininode import (
+    mininode_lock,
+    P2PInterface,
+)
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import wait_until
+
+class P2PStoreBlock(P2PInterface):
+
+    def __init__(self):
+        super().__init__()
+        self.blocks = defaultdict(int)
+
+    def on_block(self, message):
+        message.block.calc_sha256()
+        self.blocks[message.block.sha256] += 1
+
+class GetdataTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def run_test(self):
+        self.nodes[0].add_p2p_connection(P2PStoreBlock())
+
+        self.log.info("test that an invalid GETDATA doesn't prevent processing of future messages")
+
+        # Send invalid message and verify that node responds to later ping
+        invalid_getdata = msg_getdata()
+        invalid_getdata.inv.append(CInv(t=0, h=0))  # INV type 0 is invalid.
+        self.nodes[0].p2ps[0].send_and_ping(invalid_getdata)
+
+        # Check getdata still works by fetching tip block
+        best_block = int(self.nodes[0].getbestblockhash(), 16)
+        good_getdata = msg_getdata()
+        good_getdata.inv.append(CInv(t=2, h=best_block))
+        self.nodes[0].p2ps[0].send_and_ping(good_getdata)
+        wait_until(lambda: self.nodes[0].p2ps[0].blocks[best_block] == 1, timeout=30, lock=mininode_lock)
+
+if __name__ == '__main__':
+    GetdataTest().main()
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index 4855f62a8f..ef5ef49eaf 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -57,6 +57,8 @@ MSG_FILTERED_BLOCK = 3
 MSG_WITNESS_FLAG = 1 << 30
 MSG_TYPE_MASK = 0xffffffff >> 2
 
+FILTER_TYPE_BASIC = 0
+
 # Serialization/deserialization tools
 def sha256(s):
     return hashlib.new('sha256', s).digest()
@@ -1512,3 +1514,50 @@ class msg_no_witness_blocktxn(msg_blocktxn):
 
     def serialize(self):
         return self.block_transactions.serialize(with_witness=False)
+
+class msg_getcfcheckpt:
+    __slots__ = ("filter_type", "stop_hash")
+    msgtype =  b"getcfcheckpt"
+
+    def __init__(self, filter_type, stop_hash):
+        self.filter_type = filter_type
+        self.stop_hash = stop_hash
+
+    def deserialize(self, f):
+        self.filter_type = struct.unpack("<B", f.read(1))[0]
+        self.stop_hash = deser_uint256(f)
+
+    def serialize(self):
+        r = b""
+        r += struct.pack("<B", self.filter_type)
+        r += ser_uint256(self.stop_hash)
+        return r
+
+    def __repr__(self):
+        return "msg_getcfcheckpt(filter_type={:#x}, stop_hash={:x})".format(
+            self.filter_type, self.stop_hash)
+
+class msg_cfcheckpt:
+    __slots__ = ("filter_type", "stop_hash", "headers")
+    msgtype =  b"cfcheckpt"
+
+    def __init__(self, filter_type=None, stop_hash=None, headers=None):
+        self.filter_type = filter_type
+        self.stop_hash = stop_hash
+        self.headers = headers
+
+    def deserialize(self, f):
+        self.filter_type = struct.unpack("<B", f.read(1))[0]
+        self.stop_hash = deser_uint256(f)
+        self.headers = deser_uint256_vector(f)
+
+    def serialize(self):
+        r = b""
+        r += struct.pack("<B", self.filter_type)
+        r += ser_uint256(self.stop_hash)
+        r += ser_uint256_vector(self.headers)
+        return r
+
+    def __repr__(self):
+        return "msg_cfcheckpt(filter_type={:#x}, stop_hash={:x})".format(
+            self.filter_type, self.stop_hash)
diff --git a/test/functional/test_framework/mininode.py b/test/functional/test_framework/mininode.py
index 31cec66ee7..ba0391625e 100755
--- a/test/functional/test_framework/mininode.py
+++ b/test/functional/test_framework/mininode.py
@@ -31,6 +31,7 @@ from test_framework.messages import (
     msg_block,
     MSG_BLOCK,
     msg_blocktxn,
+    msg_cfcheckpt,
     msg_cmpctblock,
     msg_feefilter,
     msg_filteradd,
@@ -67,6 +68,7 @@ MESSAGEMAP = {
     b"addr": msg_addr,
     b"block": msg_block,
     b"blocktxn": msg_blocktxn,
+    b"cfcheckpt": msg_cfcheckpt,
     b"cmpctblock": msg_cmpctblock,
     b"feefilter": msg_feefilter,
     b"filteradd": msg_filteradd,
@@ -328,6 +330,7 @@ class P2PInterface(P2PConnection):
     def on_addr(self, message): pass
     def on_block(self, message): pass
     def on_blocktxn(self, message): pass
+    def on_cfcheckpt(self, message): pass
     def on_cmpctblock(self, message): pass
     def on_feefilter(self, message): pass
     def on_filteradd(self, message): pass
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 0c2ef83834..826faece68 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -110,7 +110,7 @@ class TestNode():
                          "--gen-suppressions=all", "--exit-on-first-error=yes",
                          "--error-exitcode=1", "--quiet"] + self.args
 
-        if self.version is None or self.version >= 190000:
+        if self.version_is_at_least(190000):
             self.args.append("-logthreadnames")
 
         self.cli = TestNodeCLI(bitcoin_cli, self.datadir)
@@ -222,6 +222,27 @@ class TestNode():
                 rpc = get_rpc_proxy(rpc_url(self.datadir, self.index, self.chain, self.rpchost), self.index, timeout=self.rpc_timeout, coveragedir=self.coverage_dir)
                 rpc.getblockcount()
                 # If the call to getblockcount() succeeds then the RPC connection is up
+                if self.version_is_at_least(190000):
+                    # getmempoolinfo.loaded is available since commit
+                    # bb8ae2c (version 0.19.0)
+                    wait_until(lambda: rpc.getmempoolinfo()['loaded'])
+                    # Wait for the node to finish reindex, block import, and
+                    # loading the mempool. Usually importing happens fast or
+                    # even "immediate" when the node is started. However, there
+                    # is no guarantee and sometimes ThreadImport might finish
+                    # later. This is going to cause intermittent test failures,
+                    # because generally the tests assume the node is fully
+                    # ready after being started.
+                    #
+                    # For example, the node will reject block messages from p2p
+                    # when it is still importing with the error "Unexpected
+                    # block message received"
+                    #
+                    # The wait is done here to make tests as robust as possible
+                    # and prevent racy tests and intermittent failures as much
+                    # as possible. Some tests might not need this, but the
+                    # overhead is trivial, and the added gurantees are worth
+                    # the minimal performance cost.
                 self.log.debug("RPC successfully started")
                 if self.use_cli:
                     return
@@ -274,6 +295,9 @@ class TestNode():
             wallet_path = "wallet/{}".format(urllib.parse.quote(wallet_name))
             return RPCOverloadWrapper(self.rpc / wallet_path, descriptors=self.descriptors)
 
+    def version_is_at_least(self, ver):
+        return self.version is None or self.version >= ver
+
     def stop_node(self, expected_stderr='', wait=0):
         """Stop the node."""
         if not self.running:
@@ -281,7 +305,7 @@ class TestNode():
         self.log.debug("Stopping node")
         try:
             # Do not use wait argument when testing older nodes, e.g. in feature_backwards_compatibility.py
-            if self.version is None or self.version >= 180000:
+            if self.version_is_at_least(180000):
                 self.stop(wait=wait)
             else:
                 self.stop()
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index 20ab9ee464..7466a3cab3 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -399,7 +399,11 @@ def connect_nodes(from_connection, node_num):
     from_connection.addnode(ip_port, "onetry")
     # poll until version handshake complete to avoid race conditions
     # with transaction relaying
-    wait_until(lambda:  all(peer['version'] != 0 for peer in from_connection.getpeerinfo()))
+    # See comments in net_processing:
+    # * Must have a version message before anything else
+    # * Must have a verack message before anything else
+    wait_until(lambda: all(peer['version'] != 0 for peer in from_connection.getpeerinfo()))
+    wait_until(lambda: all(peer['bytesrecv_per_msg'].pop('verack', 0) == 24 for peer in from_connection.getpeerinfo()))
 
 
 def sync_blocks(rpc_connections, *, wait=1, timeout=60):
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 45f591ba4a..7821355e29 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -157,6 +157,7 @@ BASE_SCRIPTS = [
     'rpc_deprecated.py',
     'wallet_disable.py',
     'p2p_addr_relay.py',
+    'p2p_getdata.py',
     'rpc_net.py',
     'wallet_keypool.py',
     'wallet_keypool.py --descriptors',
@@ -225,6 +226,7 @@ BASE_SCRIPTS = [
     'feature_loadblock.py',
     'p2p_dos_header_tree.py',
     'p2p_unrequested_blocks.py',
+    'p2p_blockfilters.py',
     'feature_includeconf.py',
     'feature_asmap.py',
     'mempool_unbroadcast.py',
diff --git a/test/functional/wallet_abandonconflict.py b/test/functional/wallet_abandonconflict.py
index c7b19081c8..90d17a806c 100755
--- a/test/functional/wallet_abandonconflict.py
+++ b/test/functional/wallet_abandonconflict.py
@@ -18,7 +18,6 @@ from test_framework.util import (
     assert_raises_rpc_error,
     connect_nodes,
     disconnect_nodes,
-    wait_until,
 )
 
 
@@ -98,7 +97,7 @@ class AbandonConflictTest(BitcoinTestFramework):
         # TODO: redo with eviction
         self.stop_node(0)
         self.start_node(0, extra_args=["-minrelaytxfee=0.0001"])
-        wait_until(lambda: self.nodes[0].getmempoolinfo()['loaded'])
+        assert self.nodes[0].getmempoolinfo()['loaded']
 
         # Verify txs no longer in either node's mempool
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
@@ -126,7 +125,7 @@ class AbandonConflictTest(BitcoinTestFramework):
         # Verify that even with a low min relay fee, the tx is not reaccepted from wallet on startup once abandoned
         self.stop_node(0)
         self.start_node(0, extra_args=["-minrelaytxfee=0.00001"])
-        wait_until(lambda: self.nodes[0].getmempoolinfo()['loaded'])
+        assert self.nodes[0].getmempoolinfo()['loaded']
 
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
         assert_equal(self.nodes[0].getbalance(), balance)
@@ -148,7 +147,7 @@ class AbandonConflictTest(BitcoinTestFramework):
         # Remove using high relay fee again
         self.stop_node(0)
         self.start_node(0, extra_args=["-minrelaytxfee=0.0001"])
-        wait_until(lambda: self.nodes[0].getmempoolinfo()['loaded'])
+        assert self.nodes[0].getmempoolinfo()['loaded']
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
         newbalance = self.nodes[0].getbalance()
         assert_equal(newbalance, balance - Decimal("24.9996"))
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index 2dddbf2cf3..9e295af330 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the wallet."""
 from decimal import Decimal
-import time
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
@@ -466,12 +465,8 @@ class WalletTest(BitcoinTestFramework):
         extra_args = ["-walletrejectlongchains", "-limitancestorcount=" + str(2 * chainlimit)]
         self.start_node(0, extra_args=extra_args)
 
-        # wait for loadmempool
-        timeout = 10
-        while (timeout > 0 and len(self.nodes[0].getrawmempool()) < chainlimit * 2):
-            time.sleep(0.5)
-            timeout -= 0.5
-        assert_equal(len(self.nodes[0].getrawmempool()), chainlimit * 2)
+        # wait until the wallet has submitted all transactions to the mempool
+        wait_until(lambda: len(self.nodes[0].getrawmempool()) == chainlimit * 2)
 
         node0_balance = self.nodes[0].getbalance()
         # With walletrejectlongchains we will not create the tx and store it in our wallet.
diff --git a/test/functional/wallet_upgradewallet.py b/test/functional/wallet_upgradewallet.py
index e7e71bf3f6..bb81746715 100755
--- a/test/functional/wallet_upgradewallet.py
+++ b/test/functional/wallet_upgradewallet.py
@@ -4,9 +4,11 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """upgradewallet RPC functional test
 
-Test upgradewallet RPC. Download v0.15.2 v0.16.3 node binaries:
+Test upgradewallet RPC. Download node binaries:
 
-contrib/devtools/previous_release.sh -b v0.15.2 v0.16.3
+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 and v0.16.3 are required by this test. The others are used in feature_backwards_compatibility.py
 """
 
 import os
diff --git a/test/fuzz/test_runner.py b/test/fuzz/test_runner.py
index e2454c4237..56b18752ec 100755
--- a/test/fuzz/test_runner.py
+++ b/test/fuzz/test_runner.py
@@ -38,6 +38,7 @@ def main():
     )
     parser.add_argument(
         '--par',
+        '-j',
         type=int,
         default=4,
         help='How many targets to merge or execute in parallel.',
diff --git a/test/lint/lint-shell.sh b/test/lint/lint-shell.sh
index 2bb76ec286..563e076b35 100755
--- a/test/lint/lint-shell.sh
+++ b/test/lint/lint-shell.sh
@@ -35,8 +35,9 @@ if ! command -v shellcheck > /dev/null; then
     exit $EXIT_CODE
 fi
 
+SHELLCHECK_CMD=(shellcheck --external-sources --check-sourced)
 EXCLUDE="--exclude=$(IFS=','; echo "${disabled[*]}")"
-if ! shellcheck "$EXCLUDE" $(git ls-files -- '*.sh' | grep -vE 'src/(leveldb|secp256k1|univalue)/'); then
+if ! "${SHELLCHECK_CMD[@]}" "$EXCLUDE" $(git ls-files -- '*.sh' | grep -vE 'src/(leveldb|secp256k1|univalue)/'); then
     EXIT_CODE=1
 fi
 
@@ -46,14 +47,13 @@ if ! command -v yq > /dev/null; then
 fi
 
 EXCLUDE_GITIAN=${EXCLUDE}",$(IFS=','; echo "${disabled_gitian[*]}")"
-SHELLCHECK_CMD="shellcheck --external-sources --check-sourced $EXCLUDE_GITIAN"
 for descriptor in $(git ls-files -- 'contrib/gitian-descriptors/*.yml')
 do
     script=$(basename "$descriptor")
     # Use #!/bin/bash as gitian-builder/bin/gbuild does to complete a script.
     echo "#!/bin/bash" > $script
     yq -r .script "$descriptor" >> $script
-    if ! $SHELLCHECK_CMD $script; then
+    if ! "${SHELLCHECK_CMD[@]}" "$EXCLUDE_GITIAN" $script; then
         EXIT_CODE=1
     fi
     rm $script