Merge #12134: Build previous releases and run functional tests

c456145b2c65f580683df03bf10cd39000cf24d5 [test] add 0.19 backwards compatibility tests (Sjors Provoost)
b769cd142deda74fe46e231cc7b687a86514f2f1 [test] add v0.17.1 wallet upgrade test (Sjors Provoost)
9d9390dab716f07057c94e8e21f3c7dd06192f35 [tests] add wallet backwards compatility tests (Sjors Provoost)
c7ca6308968b29a0e0edc485cd06e68e5edb7c7d [scripts] support release candidates of earlier releases (Sjors Provoost)
8b1460dbd1b732f06d4cebe1fa6844286c7a0056 [tests] check v0.17.1 and v0.18.1 backwards compatibility (Sjors Provoost)
ae379cf7d12943fc192d58176673bcfe7d53da53 [scripts] build earlier releases (Sjors Provoost)

Pull request description:

  This PR adds binaries for 0.17, 0.18 and 0.19 to Travis and runs a basic block propagation test.

  Includes test for upgrading v0.17.1 wallets and opening master wallets with older versions.

  Usage:

  ```sh
  contrib/devtools/previous_release.sh -f -b v0.19.0.1 v0.18.1 v0.17.1
  test/functional/backwards_compatibility.py
  ```

  Travis caches these earlier releases, so it should be able to run these tests with little performance impact.

  Additional scenarios where it might be useful to run tests against earlier releases:

  * creating a wallet with #11403's segwit implementation, copying it to an older node and making sure the user didn't lose any funds (although this PR doesn't support `v0.15.1`)
  * future consensus changes
  * P2P changes (e.g. to make sure we don't accidentally ban old nodes)

ACKs for top commit:
  MarcoFalke:
    ACK c456145b2c65f580683df03bf10cd39000cf24d5 🔨

Tree-SHA512: 360bd870603f95b14dc0cd629532cc147344f632b808617c18e1b585dfb1f082b401e5d493a48196b719e0aeaee533ae0a773dfc9f217f704aae898576c19232

12 files changed, 521 insertions, 8 deletions

diff --git a/.gitignore b/.gitignore
index db493811c5..bc8751c805 100644
--- a/.gitignore
+++ b/.gitignore
@@ -108,6 +108,9 @@ qrc_*.cpp
 .DS_Store
 build
 
+# Previous releases
+releases
+
 #lcov
 *.gcno
 *.gcda
diff --git a/.travis.yml b/.travis.yml
index 364278ee6a..c5b8c476b7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -35,6 +35,7 @@ cache:
     - $TRAVIS_BUILD_DIR/depends/built
     - $TRAVIS_BUILD_DIR/depends/sdk-sources
     - $TRAVIS_BUILD_DIR/ci/scratch/.ccache
+    - $TRAVIS_BUILD_DIR/releases/$HOST
     # macOS
     - $HOME/Library/Caches/Homebrew
     - /usr/local/Homebrew
@@ -108,7 +109,7 @@ jobs:
         FILE_ENV="./ci/test/00_setup_env_i686_centos.sh"
 
     - stage: test
-      name: 'x86_64 Linux  [GOAL: install]  [bionic]  [uses qt5 dev package and some depends packages] [unsigned char]'
+      name: 'x86_64 Linux  [GOAL: install]  [bionic]  [previous releases, uses qt5 dev package and some depends packages] [unsigned char]'
       env: >-
         FILE_ENV="./ci/test/00_setup_env_native_qt5.sh"
 
diff --git a/ci/README.md b/ci/README.md
index 880e49b459..d2ea255b4b 100644
--- a/ci/README.md
+++ b/ci/README.md
@@ -13,7 +13,7 @@ If the repository is not a fresh git clone, you might have to clean files from p
 
 The ci needs to perform various sysadmin tasks such as installing packages or writing to the user's home directory.
 While most of the actions are done inside a docker container, this is not possible for all. Thus, cache directories,
-such as the depends cache or ccache, are mounted as read-write into the docker container. While it should be fine to run
+such as the depends cache, previous release binaries, or ccache, are mounted as read-write into the docker container. While it should be fine to run
 the ci system locally on you development box, the ci scripts can generally be assumed to have received less review and
 testing compared to other parts of the codebase. If you want to keep the work tree clean, you might want to run the ci
 system in a virtual machine with a Linux operating system of your choice.
diff --git a/ci/test/00_setup_env.sh b/ci/test/00_setup_env.sh
index eb00e9c705..4c22e4e6c5 100755
--- a/ci/test/00_setup_env.sh
+++ b/ci/test/00_setup_env.sh
@@ -33,6 +33,7 @@ export HOST=${HOST:-$("$BASE_ROOT_DIR/depends/config.guess")}
 export USE_BUSY_BOX=${USE_BUSY_BOX:-false}
 export RUN_UNIT_TESTS=${RUN_UNIT_TESTS:-true}
 export RUN_FUNCTIONAL_TESTS=${RUN_FUNCTIONAL_TESTS:-true}
+export TEST_PREVIOUS_RELEASES=${TEST_PREVIOUS_RELEASES:-false}
 export RUN_FUZZ_TESTS=${RUN_FUZZ_TESTS:-false}
 export CONTAINER_NAME=${CONTAINER_NAME:-ci_unnamed}
 export DOCKER_NAME_TAG=${DOCKER_NAME_TAG:-ubuntu:18.04}
@@ -50,6 +51,7 @@ export CCACHE_DIR=${CCACHE_DIR:-$BASE_SCRATCH_DIR/.ccache}
 export DEPENDS_DIR=${DEPENDS_DIR:-$BASE_ROOT_DIR/depends}
 # Folder where the build is done (bin and lib).
 export BASE_OUTDIR=${BASE_OUTDIR:-$BASE_SCRATCH_DIR/out/$HOST}
+export PREVIOUS_RELEASES_DIR=${PREVIOUS_RELEASES_DIR:-$BASE_ROOT_DIR/releases/$HOST}
 export SDK_URL=${SDK_URL:-https://bitcoincore.org/depends-sources/sdks}
 export WINEDEBUG=${WINEDEBUG:-fixme-all}
 export DOCKER_PACKAGES=${DOCKER_PACKAGES:-build-essential libtool autotools-dev automake pkg-config bsdmainutils curl ca-certificates ccache python3 rsync git procps}
diff --git a/ci/test/00_setup_env_native_qt5.sh b/ci/test/00_setup_env_native_qt5.sh
index 1c11936262..21c15236d2 100644
--- a/ci/test/00_setup_env_native_qt5.sh
+++ b/ci/test/00_setup_env_native_qt5.sh
@@ -11,4 +11,5 @@ export PACKAGES="python3-zmq qtbase5-dev qttools5-dev-tools libdbus-1-dev libhar
 export DEP_OPTS="NO_QT=1 NO_UPNP=1 DEBUG=1 ALLOW_HOST_PACKAGES=1"
 export TEST_RUNNER_EXTRA="--coverage --extended --exclude feature_dbcrash"  # Run extended tests so that coverage does not fail, but exclude the very slow dbcrash
 export GOAL="install"
+export TEST_PREVIOUS_RELEASES=true
 export BITCOIN_CONFIG="--enable-zmq --with-gui=qt5 --enable-glibc-back-compat --enable-reduce-exports --enable-debug CFLAGS=\"-g0 -O2 -funsigned-char\" CXXFLAGS=\"-g0 -O2 -funsigned-char\""
diff --git a/ci/test/04_install.sh b/ci/test/04_install.sh
index 477fd1e329..c6e8331a71 100755
--- a/ci/test/04_install.sh
+++ b/ci/test/04_install.sh
@@ -40,12 +40,13 @@ fi
 
 mkdir -p "${BASE_SCRATCH_DIR}"
 mkdir -p "${CCACHE_DIR}"
+mkdir -p "${PREVIOUS_RELEASES_DIR}"
 
 export ASAN_OPTIONS="detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1"
 export LSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/lsan"
 export TSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/tsan:log_path=${BASE_SCRATCH_DIR}/sanitizer-output/tsan"
 export UBSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1"
-env | grep -E '^(BITCOIN_CONFIG|BASE_|QEMU_|CCACHE_|WINEDEBUG|LC_ALL|BOOST_TEST_RANDOM|CONFIG_SHELL|(ASAN|LSAN|TSAN|UBSAN)_OPTIONS)' | tee /tmp/env
+env | grep -E '^(BITCOIN_CONFIG|BASE_|QEMU_|CCACHE_|WINEDEBUG|LC_ALL|BOOST_TEST_RANDOM|CONFIG_SHELL|(ASAN|LSAN|TSAN|UBSAN)_OPTIONS|TEST_PREVIOUS_RELEASES|PREVIOUS_RELEASES_DIR)' | tee /tmp/env
 if [[ $HOST = *-mingw32 ]]; then
   DOCKER_ADMIN="--cap-add SYS_ADMIN"
 elif [[ $BITCOIN_CONFIG = *--with-sanitizers=*address* ]]; then # If ran with (ASan + LSan), Docker needs access to ptrace (https://github.com/google/sanitizers/issues/764)
@@ -62,6 +63,7 @@ if [ -z "$RUN_CI_ON_HOST" ]; then
                   --mount type=bind,src=$BASE_ROOT_DIR,dst=/ro_base,readonly \
                   --mount type=bind,src=$CCACHE_DIR,dst=$CCACHE_DIR \
                   --mount type=bind,src=$DEPENDS_DIR,dst=$DEPENDS_DIR \
+                  --mount type=bind,src=$PREVIOUS_RELEASES_DIR,dst=$PREVIOUS_RELEASES_DIR \
                   -w $BASE_ROOT_DIR \
                   --env-file /tmp/env \
                   --name $CONTAINER_NAME \
diff --git a/ci/test/05_before_script.sh b/ci/test/05_before_script.sh
index d8aa5c87a2..1cb5c30901 100755
--- a/ci/test/05_before_script.sh
+++ b/ci/test/05_before_script.sh
@@ -35,3 +35,8 @@ if [ -z "$NO_DEPENDS" ]; then
   fi
   DOCKER_EXEC $SHELL_OPTS make $MAKEJOBS -C depends HOST=$HOST $DEP_OPTS
 fi
+if [ "$TEST_PREVIOUS_RELEASES" = "true" ]; then
+  BEGIN_FOLD previous-versions
+  DOCKER_EXEC contrib/devtools/previous_release.sh -b -t "$PREVIOUS_RELEASES_DIR" v0.17.1 v0.18.1 v0.19.0.1
+  END_FOLD
+fi
diff --git a/contrib/devtools/previous_release.sh b/contrib/devtools/previous_release.sh
new file mode 100755
index 0000000000..efd035f778
--- /dev/null
+++ b/contrib/devtools/previous_release.sh
@@ -0,0 +1,149 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2018-2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+# Build previous releases.
+
+export LC_ALL=C
+
+CONFIG_FLAGS=""
+FUNCTIONAL_TESTS=0
+DELETE_EXISTING=0
+USE_DEPENDS=0
+DOWNLOAD_BINARY=0
+CONFIG_FLAGS=""
+TARGET="releases"
+
+while getopts ":hfrdbt:" opt; do
+  case $opt in
+    h)
+      echo "Usage: .previous_release.sh [options] tag1 tag2"
+      echo "  options:"
+      echo "  -h   Print this message"
+      echo "  -f   Configure for functional tests"
+      echo "  -r   Remove existing directory"
+      echo "  -d   Use depends"
+      echo "  -b   Download release binary"
+      echo "  -t   Target directory (default: releases)"
+      exit 0
+      ;;
+    f)
+      FUNCTIONAL_TESTS=1
+      CONFIG_FLAGS="$CONFIG_FLAGS --without-gui --disable-tests --disable-bench"
+      ;;
+    r)
+      DELETE_EXISTING=1
+      ;;
+    d)
+      USE_DEPENDS=1
+      ;;
+    b)
+      DOWNLOAD_BINARY=1
+      ;;
+    t)
+      TARGET=$OPTARG
+      ;;
+    \?)
+      echo "Invalid option: -$OPTARG" >&2
+      exit 1
+      ;;
+  esac
+done
+
+shift $((OPTIND-1))
+
+if [ -z "$1" ]; then
+  echo "Specify release tag(s), e.g.: .previous_release v0.15.1"
+  exit 1
+fi
+
+if [ ! -d "$TARGET" ]; then
+  mkdir -p $TARGET
+fi
+
+if [ "$DOWNLOAD_BINARY" -eq "1" ]; then
+  HOST="${HOST:-$(./depends/config.guess)}"
+  case "$HOST" in
+    x86_64-*-linux*)
+      PLATFORM=x86_64-linux-gnu
+      ;;
+    x86_64-apple-darwin*)
+      PLATFORM=osx64
+      ;;
+    *)
+      echo "Not sure which binary to download for $HOST."
+      exit 1
+      ;;
+  esac
+fi
+
+echo "Releases directory: $TARGET"
+pushd "$TARGET" || exit 1
+{
+  for tag in "$@"
+  do
+    if [ "$DELETE_EXISTING" -eq "1" ]; then
+      if [ -d "$tag" ]; then
+        rm -r "$tag"
+      fi
+    fi
+
+    if [ "$DOWNLOAD_BINARY" -eq "0" ]; then
+
+      if [ ! -d "$tag" ]; then
+        if [ -z $(git tag -l "$tag") ]; then
+          echo "Tag $tag not found"
+          exit 1
+        fi
+
+        git clone https://github.com/bitcoin/bitcoin "$tag"
+        pushd "$tag" || exit 1
+        {
+          git checkout "$tag"
+          if [ "$USE_DEPENDS" -eq "1" ]; then
+            pushd depends || exit 1
+            {
+              if [ "$FUNCTIONAL_TESTS" -eq "1" ]; then
+                make NO_QT=1
+              else
+                make
+              fi
+              HOST="${HOST:-$(./config.guess)}"
+            }
+            popd || exit 1
+            CONFIG_FLAGS="--prefix=$PWD/depends/$HOST $CONFIG_FLAGS"
+          fi
+          ./autogen.sh
+          ./configure $CONFIG_FLAGS
+          make
+          # Move binaries, so they're in the same place as in the release download:
+          mkdir bin
+          mv src/bitcoind src/bitcoin-cli src/bitcoin-tx bin
+          if [ "$FUNCTIONAL_TESTS" -eq "0" ]; then
+            mv src/qt/bitcoin-qt bin
+          fi
+        }
+        popd || exit 1
+      fi
+    else
+      if [ -d "$tag" ]; then
+        echo "Using cached $tag"
+      else
+        mkdir "$tag"
+        if [[ "$tag" =~ v(.*)(rc[0-9]+)$ ]]; then
+            BIN_PATH="bin/bitcoin-core-${BASH_REMATCH[1]}/test.${BASH_REMATCH[2]}"
+        else
+            BIN_PATH="bin/bitcoin-core-${tag:1}"
+        fi
+        URL="https://bitcoin.org/$BIN_PATH/bitcoin-${tag:1}-$PLATFORM.tar.gz"
+        echo "Fetching: $URL"
+        curl -O $URL
+        tar -zxf "bitcoin-${tag:1}-$PLATFORM.tar.gz" -C "$tag" --strip-components=1 "bitcoin-${tag:1}"
+        rm "bitcoin-${tag:1}-$PLATFORM.tar.gz"
+      fi
+    fi
+  done
+}
+popd || exit 1
diff --git a/test/functional/feature_backwards_compatibility.py b/test/functional/feature_backwards_compatibility.py
new file mode 100755
index 0000000000..1ac10f971a
--- /dev/null
+++ b/test/functional/feature_backwards_compatibility.py
@@ -0,0 +1,335 @@
+#!/usr/bin/env python3
+# Copyright (c) 2018-2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Backwards compatibility functional test
+
+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
+
+Due to RPC changes introduced in various versions the below tests
+won't work for older versions without some patches or workarounds.
+
+Use only the latest patch version of each release, unless a test specifically
+needs an older patch version.
+"""
+
+import os
+import shutil
+
+from test_framework.test_framework import BitcoinTestFramework, SkipTest
+from test_framework.descriptors import descsum_create
+
+from test_framework.util import (
+    assert_equal,
+    sync_blocks,
+    sync_mempools
+)
+
+class BackwardsCompatibilityTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 5
+        # 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"], # v0.18.1
+            ["-nowallet", "-walletrbf=1", "-addresstype=bech32"] # v0.17.1
+        ]
+
+    def setup_nodes(self):
+        if os.getenv("TEST_PREVIOUS_RELEASES") == "false":
+            raise SkipTest("backwards compatibility tests")
+
+        releases_path = os.getenv("PREVIOUS_RELEASES_DIR") or os.getcwd() + "/releases"
+        if not os.path.isdir(releases_path):
+            if os.getenv("TEST_PREVIOUS_RELEASES") == "true":
+                raise AssertionError("TEST_PREVIOUS_RELEASES=1 but releases missing: " + releases_path)
+            raise SkipTest("This test requires binaries for previous releases")
+
+        self.add_nodes(self.num_nodes, extra_args=self.extra_args, versions=[
+            None,
+            None,
+            190000,
+            180100,
+            170100
+        ], binary=[
+            self.options.bitcoind,
+            self.options.bitcoind,
+            releases_path + "/v0.19.0.1/bin/bitcoind",
+            releases_path + "/v0.18.1/bin/bitcoind",
+            releases_path + "/v0.17.1/bin/bitcoind"
+        ], binary_cli=[
+            self.options.bitcoincli,
+            self.options.bitcoincli,
+            releases_path + "/v0.19.0.1/bin/bitcoin-cli",
+            releases_path + "/v0.18.1/bin/bitcoin-cli",
+            releases_path + "/v0.17.1/bin/bitcoin-cli"
+        ])
+
+        self.start_nodes()
+
+    def run_test(self):
+        self.nodes[0].generatetoaddress(101, self.nodes[0].getnewaddress())
+
+        sync_blocks(self.nodes)
+
+        # Sanity check the test framework:
+        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]
+
+        self.log.info("Test wallet backwards compatibility...")
+        # Create a number of wallets and open them in older versions:
+
+        # w1: regular wallet, created on master: update this test when default
+        #     wallets can no longer be opened by older versions.
+        node_master.createwallet(wallet_name="w1")
+        wallet = node_master.get_wallet_rpc("w1")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+        # Create a confirmed transaction, receiving coins
+        address = wallet.getnewaddress()
+        self.nodes[0].sendtoaddress(address, 10)
+        sync_mempools(self.nodes)
+        self.nodes[0].generate(1)
+        sync_blocks(self.nodes)
+        # Create a conflicting transaction using RBF
+        return_address = self.nodes[0].getnewaddress()
+        tx1_id = self.nodes[1].sendtoaddress(return_address, 1)
+        tx2_id = self.nodes[1].bumpfee(tx1_id)["txid"]
+        # Confirm the transaction
+        sync_mempools(self.nodes)
+        self.nodes[0].generate(1)
+        sync_blocks(self.nodes)
+        # Create another conflicting transaction using RBF
+        tx3_id = self.nodes[1].sendtoaddress(return_address, 1)
+        tx4_id = self.nodes[1].bumpfee(tx3_id)["txid"]
+        # Abondon transaction, but don't confirm
+        self.nodes[1].abandontransaction(tx3_id)
+
+        # w1_v19: regular wallet, created with v0.19
+        node_v19.createwallet(wallet_name="w1_v19")
+        wallet = node_v19.get_wallet_rpc("w1_v19")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+
+        # w1_v18: regular wallet, created with v0.18
+        node_v18.createwallet(wallet_name="w1_v18")
+        wallet = node_v18.get_wallet_rpc("w1_v18")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+
+        # w2: wallet with private keys disabled, created on master: update this
+        #     test when default wallets private keys disabled can no longer be
+        #     opened by older versions.
+        node_master.createwallet(wallet_name="w2", disable_private_keys=True)
+        wallet = node_master.get_wallet_rpc("w2")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        # w2_v19: wallet with private keys disabled, created with v0.19
+        node_v19.createwallet(wallet_name="w2_v19", disable_private_keys=True)
+        wallet = node_v19.get_wallet_rpc("w2_v19")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        # w2_v18: wallet with private keys disabled, created with v0.18
+        node_v18.createwallet(wallet_name="w2_v18", disable_private_keys=True)
+        wallet = node_v18.get_wallet_rpc("w2_v18")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        # w3: blank wallet, created on master: update this
+        #     test when default blank wallets can no longer be opened by older versions.
+        node_master.createwallet(wallet_name="w3", blank=True)
+        wallet = node_master.get_wallet_rpc("w3")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] == 0
+
+        # w3_v19: blank wallet, created with v0.19
+        node_v19.createwallet(wallet_name="w3_v19", blank=True)
+        wallet = node_v19.get_wallet_rpc("w3_v19")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] == 0
+
+        # w3_v18: blank wallet, created with v0.18
+        node_v18.createwallet(wallet_name="w3_v18", blank=True)
+        wallet = node_v18.get_wallet_rpc("w3_v18")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] == 0
+
+        # Copy the wallets to older nodes:
+        node_master_wallets_dir = os.path.join(node_master.datadir, "regtest/wallets")
+        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_master.unloadwallet("w1")
+        node_master.unloadwallet("w2")
+        node_v19.unloadwallet("w1_v19")
+        node_v19.unloadwallet("w2_v19")
+        node_v18.unloadwallet("w1_v18")
+        node_v18.unloadwallet("w2_v18")
+
+        # Copy wallets to v0.17
+        for wallet in os.listdir(node_master_wallets_dir):
+            shutil.copytree(
+                os.path.join(node_master_wallets_dir, wallet),
+                os.path.join(node_v17_wallets_dir, wallet)
+            )
+        for wallet in os.listdir(node_v18_wallets_dir):
+            shutil.copytree(
+                os.path.join(node_v18_wallets_dir, wallet),
+                os.path.join(node_v17_wallets_dir, wallet)
+            )
+
+        # Copy wallets to v0.18
+        for wallet in os.listdir(node_master_wallets_dir):
+            shutil.copytree(
+                os.path.join(node_master_wallets_dir, wallet),
+                os.path.join(node_v18_wallets_dir, wallet)
+            )
+
+        # Copy wallets to v0.19
+        for wallet in os.listdir(node_master_wallets_dir):
+            shutil.copytree(
+                os.path.join(node_master_wallets_dir, wallet),
+                os.path.join(node_v19_wallets_dir, wallet)
+            )
+
+        # Open the wallets in v0.19
+        node_v19.loadwallet("w1")
+        wallet = node_v19.get_wallet_rpc("w1")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+        txs = wallet.listtransactions()
+        assert_equal(len(txs), 5)
+        assert_equal(txs[1]["txid"], tx1_id)
+        assert_equal(txs[2]["walletconflicts"], [tx1_id])
+        assert_equal(txs[1]["replaced_by_txid"], tx2_id)
+        assert not(txs[1]["abandoned"])
+        assert_equal(txs[1]["confirmations"], -1)
+        assert_equal(txs[2]["blockindex"], 1)
+        assert txs[3]["abandoned"]
+        assert_equal(txs[4]["walletconflicts"], [tx3_id])
+        assert_equal(txs[3]["replaced_by_txid"], tx4_id)
+        assert not(hasattr(txs[3], "blockindex"))
+
+        node_v19.loadwallet("w2")
+        wallet = node_v19.get_wallet_rpc("w2")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        node_v19.loadwallet("w3")
+        wallet = node_v19.get_wallet_rpc("w3")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] == 0
+
+        # Open the wallets in v0.18
+        node_v18.loadwallet("w1")
+        wallet = node_v18.get_wallet_rpc("w1")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+        txs = wallet.listtransactions()
+        assert_equal(len(txs), 5)
+        assert_equal(txs[1]["txid"], tx1_id)
+        assert_equal(txs[2]["walletconflicts"], [tx1_id])
+        assert_equal(txs[1]["replaced_by_txid"], tx2_id)
+        assert not(txs[1]["abandoned"])
+        assert_equal(txs[1]["confirmations"], -1)
+        assert_equal(txs[2]["blockindex"], 1)
+        assert txs[3]["abandoned"]
+        assert_equal(txs[4]["walletconflicts"], [tx3_id])
+        assert_equal(txs[3]["replaced_by_txid"], tx4_id)
+        assert not(hasattr(txs[3], "blockindex"))
+
+        node_v18.loadwallet("w2")
+        wallet = node_v18.get_wallet_rpc("w2")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        node_v18.loadwallet("w3")
+        wallet = node_v18.get_wallet_rpc("w3")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] == 0
+
+        # Open the wallets in v0.17
+        node_v17.loadwallet("w1_v18")
+        wallet = node_v17.get_wallet_rpc("w1_v18")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+
+        node_v17.loadwallet("w1")
+        wallet = node_v17.get_wallet_rpc("w1")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled']
+        assert info['keypoolsize'] > 0
+
+        node_v17.loadwallet("w2_v18")
+        wallet = node_v17.get_wallet_rpc("w2_v18")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        node_v17.loadwallet("w2")
+        wallet = node_v17.get_wallet_rpc("w2")
+        info = wallet.getwalletinfo()
+        assert info['private_keys_enabled'] == False
+        assert info['keypoolsize'] == 0
+
+        # RPC loadwallet failure causes bitcoind to exit, in addition to the RPC
+        # call failure, so the following test won't work:
+        # 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)
+        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.log.info("Test wallet upgrade path...")
+        # u1: regular wallet, created with v0.17
+        node_v17.createwallet(wallet_name="u1_v17")
+        wallet = node_v17.get_wallet_rpc("u1_v17")
+        address = wallet.getnewaddress("bech32")
+        info = wallet.getaddressinfo(address)
+        hdkeypath = info["hdkeypath"]
+        pubkey = info["pubkey"]
+
+        # Copy the wallet to the last Bitcoin Core version and open it:
+        node_v17.unloadwallet("u1_v17")
+        shutil.copytree(
+            os.path.join(node_v17_wallets_dir, "u1_v17"),
+            os.path.join(node_master_wallets_dir, "u1_v17")
+        )
+        node_master.loadwallet("u1_v17")
+        wallet = node_master.get_wallet_rpc("u1_v17")
+        info = wallet.getaddressinfo(address)
+        descriptor = "wpkh([" + info["hdmasterfingerprint"] + hdkeypath[1:] + "]" + pubkey + ")"
+        assert_equal(info["desc"], descsum_create(descriptor))
+
+if __name__ == '__main__':
+    BackwardsCompatibilityTest().main()
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index da92c6325a..e36fb350c6 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -369,7 +369,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
     # Public helper methods. These can be accessed by the subclass test scripts.
 
-    def add_nodes(self, num_nodes, extra_args=None, *, rpchost=None, binary=None):
+    def add_nodes(self, num_nodes, extra_args=None, *, rpchost=None, binary=None, binary_cli=None, versions=None):
         """Instantiate TestNode objects.
 
         Should only be called once after the nodes have been specified in
@@ -380,11 +380,17 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
             extra_confs = [[]] * num_nodes
         if extra_args is None:
             extra_args = [[]] * num_nodes
+        if versions is None:
+            versions = [None] * num_nodes
         if binary is None:
             binary = [self.options.bitcoind] * num_nodes
+        if binary_cli is None:
+            binary_cli = [self.options.bitcoincli] * num_nodes
         assert_equal(len(extra_confs), num_nodes)
         assert_equal(len(extra_args), num_nodes)
+        assert_equal(len(versions), num_nodes)
         assert_equal(len(binary), num_nodes)
+        assert_equal(len(binary_cli), num_nodes)
         for i in range(num_nodes):
             self.nodes.append(TestNode(
                 i,
@@ -393,7 +399,8 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 rpchost=rpchost,
                 timewait=self.rpc_timeout,
                 bitcoind=binary[i],
-                bitcoin_cli=self.options.bitcoincli,
+                bitcoin_cli=binary_cli[i],
+                version=versions[i],
                 coverage_dir=self.options.coveragedir,
                 cwd=self.options.tmpdir,
                 extra_conf=extra_confs[i],
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 0742dbe617..c7559ac7c8 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -60,7 +60,7 @@ class TestNode():
     To make things easier for the test writer, any unrecognised messages will
     be dispatched to the RPC connection."""
 
-    def __init__(self, i, datadir, *, chain, rpchost, timewait, bitcoind, bitcoin_cli, coverage_dir, cwd, extra_conf=None, extra_args=None, use_cli=False, start_perf=False, use_valgrind=False):
+    def __init__(self, i, datadir, *, chain, rpchost, timewait, bitcoind, bitcoin_cli, coverage_dir, cwd, extra_conf=None, extra_args=None, use_cli=False, start_perf=False, use_valgrind=False, version=None):
         """
         Kwargs:
             start_perf (bool): If True, begin profiling the node with `perf` as soon as
@@ -84,6 +84,7 @@ class TestNode():
         # For those callers that need more flexibility, they can just set the args property directly.
         # Note that common args are set in the config file (see initialize_datadir)
         self.extra_args = extra_args
+        self.version = version
         # Configuration for logging is set as command-line args rather than in the bitcoin.conf file.
         # This means that starting a bitcoind using the temp dir to debug a failed test won't
         # spam debug.log.
@@ -91,7 +92,6 @@ class TestNode():
             self.binary,
             "-datadir=" + self.datadir,
             "-logtimemicros",
-            "-logthreadnames",
             "-debug",
             "-debugexclude=libevent",
             "-debugexclude=leveldb",
@@ -107,6 +107,9 @@ 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:
+            self.args.append("-logthreadnames")
+
         self.cli = TestNodeCLI(bitcoin_cli, self.datadir)
         self.use_cli = use_cli
         self.start_perf = start_perf
@@ -254,7 +257,11 @@ class TestNode():
             return
         self.log.debug("Stopping node")
         try:
-            self.stop(wait=wait)
+            # 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:
+                self.stop(wait=wait)
+            else:
+                self.stop()
         except http.client.CannotSendRequest:
             self.log.exception("Unable to stop node.")
 
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 8b527bcff0..ea8a340081 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -158,6 +158,7 @@ BASE_SCRIPTS = [
     'feature_assumevalid.py',
     'example_test.py',
     'wallet_txn_doublespend.py',
+    'feature_backwards_compatibility.py',
     'wallet_txn_clone.py --mineblock',
     'feature_notifications.py',
     'rpc_getblockfilter.py',