[tests] check v0.17.1 and v0.18.1 backwards compatibility

test/functional/feature_backwards_compatibility.py

@@ -0,0 +1,78 @@
+#!/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 v0.18.1 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
+
+from test_framework.test_framework import BitcoinTestFramework, SkipTest
+
+from test_framework.util import (
+    assert_equal,
+    sync_blocks
+)
+
+class BackwardsCompatibilityTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 4
+        # Add new version after each release:
+        self.extra_args = [
+            [], # Pre-release: use to mine blocks
+            [], # Pre-release: use to receive coins, swap wallets, etc
+            [], # v0.18.1
+            [] # 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,
+            180100,
+            170100
+        ], binary=[
+            self.options.bitcoind,
+            self.options.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 + "/v0.18.1/bin/bitcoin-cli",
+            releases_path + "/v0.17.1/bin/bitcoin-cli"
+        ])
+
+        self.start_nodes()
+
+    def run_test(self):
+        self.nodes[0].generate(101)
+
+        sync_blocks(self.nodes)
+
+        # Sanity check the test framework:
+        res = self.nodes[self.num_nodes - 1].getblockchaininfo()
+        assert_equal(res['blocks'], 101)
+
+if __name__ == '__main__':
+    BackwardsCompatibilityTest().main()