test: add feature_assumeutxo functional test

Most ideas for test improvements (TODOs) provided by Russ Yanofsky.

3 files changed, 251 insertions, 0 deletions

diff --git a/test/functional/feature_assumeutxo.py b/test/functional/feature_assumeutxo.py
new file mode 100755
index 0000000000..be1aa18993
--- /dev/null
+++ b/test/functional/feature_assumeutxo.py
@@ -0,0 +1,246 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 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 for assumeutxo, a means of quickly bootstrapping a node using
+a serialized version of the UTXO set at a certain height, which corresponds
+to a hash that has been compiled into bitcoind.
+
+The assumeutxo value generated and used here is committed to in
+`CRegTestParams::m_assumeutxo_data` in `src/chainparams.cpp`.
+
+## Possible test improvements
+
+- TODO: test submitting a transaction and verifying it appears in mempool
+- TODO: test what happens with -reindex and -reindex-chainstate before the
+      snapshot is validated, and make sure it's deleted successfully.
+
+Interesting test cases could be loading an assumeutxo snapshot file with:
+
+- TODO: An invalid hash
+- TODO: Valid hash but invalid snapshot file (bad coin height or truncated file or
+      bad other serialization)
+- TODO: Valid snapshot file, but referencing an unknown block
+- TODO: Valid snapshot file, but referencing a snapshot block that turns out to be
+      invalid, or has an invalid parent
+- TODO: Valid snapshot file and snapshot block, but the block is not on the
+      most-work chain
+
+Interesting starting states could be loading a snapshot when the current chain tip is:
+
+- TODO: An ancestor of snapshot block
+- TODO: Not an ancestor of the snapshot block but has less work
+- TODO: The snapshot block
+- TODO: A descendant of the snapshot block
+- TODO: Not an ancestor or a descendant of the snapshot block and has more work
+
+"""
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal, wait_until_helper
+
+START_HEIGHT = 199
+SNAPSHOT_BASE_HEIGHT = 299
+FINAL_HEIGHT = 399
+COMPLETE_IDX = {'synced': True, 'best_block_height': FINAL_HEIGHT}
+
+
+class AssumeutxoTest(BitcoinTestFramework):
+
+    def set_test_params(self):
+        """Use the pregenerated, deterministic chain up to height 199."""
+        self.num_nodes = 3
+        self.rpc_timeout = 120
+        self.extra_args = [
+            [],
+            ["-fastprune", "-prune=1", "-blockfilterindex=1", "-coinstatsindex=1"],
+            ["-txindex=1", "-blockfilterindex=1", "-coinstatsindex=1"],
+        ]
+
+    def setup_network(self):
+        """Start with the nodes disconnected so that one can generate a snapshot
+        including blocks the other hasn't yet seen."""
+        self.add_nodes(3)
+        self.start_nodes(extra_args=self.extra_args)
+
+    def run_test(self):
+        """
+        Bring up two (disconnected) nodes, mine some new blocks on the first,
+        and generate a UTXO snapshot.
+
+        Load the snapshot into the second, ensure it syncs to tip and completes
+        background validation when connected to the first.
+        """
+        n0 = self.nodes[0]
+        n1 = self.nodes[1]
+        n2 = self.nodes[2]
+
+        # Mock time for a deterministic chain
+        for n in self.nodes:
+            n.setmocktime(n.getblockheader(n.getbestblockhash())['time'])
+
+        self.sync_blocks()
+
+        def no_sync():
+            pass
+
+        # Generate a series of blocks that `n0` will have in the snapshot,
+        # but that n1 doesn't yet see. In order for the snapshot to activate,
+        # though, we have to ferry over the new headers to n1 so that it
+        # isn't waiting forever to see the header of the snapshot's base block
+        # while disconnected from n0.
+        for i in range(100):
+            self.generate(n0, nblocks=1, sync_fun=no_sync)
+            newblock = n0.getblock(n0.getbestblockhash(), 0)
+
+            # make n1 aware of the new header, but don't give it the block.
+            n1.submitheader(newblock)
+            n2.submitheader(newblock)
+
+        # Ensure everyone is seeing the same headers.
+        for n in self.nodes:
+            assert_equal(n.getblockchaininfo()["headers"], SNAPSHOT_BASE_HEIGHT)
+
+        self.log.info("-- Testing assumeutxo + some indexes + pruning")
+
+        assert_equal(n0.getblockcount(), SNAPSHOT_BASE_HEIGHT)
+        assert_equal(n1.getblockcount(), START_HEIGHT)
+
+        self.log.info(f"Creating a UTXO snapshot at height {SNAPSHOT_BASE_HEIGHT}")
+        dump_output = n0.dumptxoutset('utxos.dat')
+
+        assert_equal(
+            dump_output['txoutset_hash'],
+            'ef45ccdca5898b6c2145e4581d2b88c56564dd389e4bd75a1aaf6961d3edd3c0')
+        assert_equal(dump_output['nchaintx'], 300)
+        assert_equal(n0.getblockchaininfo()["blocks"], SNAPSHOT_BASE_HEIGHT)
+
+        # Mine more blocks on top of the snapshot that n1 hasn't yet seen. This
+        # will allow us to test n1's sync-to-tip on top of a snapshot.
+        self.generate(n0, nblocks=100, sync_fun=no_sync)
+
+        assert_equal(n0.getblockcount(), FINAL_HEIGHT)
+        assert_equal(n1.getblockcount(), START_HEIGHT)
+
+        assert_equal(n0.getblockchaininfo()["blocks"], FINAL_HEIGHT)
+
+        self.log.info(f"Loading snapshot into second node from {dump_output['path']}")
+        loaded = n1.loadtxoutset(dump_output['path'])
+        assert_equal(loaded['coins_loaded'], SNAPSHOT_BASE_HEIGHT)
+        assert_equal(loaded['base_height'], SNAPSHOT_BASE_HEIGHT)
+
+        monitor = n1.getchainstates()
+        assert_equal(monitor['normal']['blocks'], START_HEIGHT)
+        assert_equal(monitor['snapshot']['blocks'], SNAPSHOT_BASE_HEIGHT)
+        assert_equal(monitor['snapshot']['snapshot_blockhash'], dump_output['base_hash'])
+
+        assert_equal(n1.getblockchaininfo()["blocks"], SNAPSHOT_BASE_HEIGHT)
+
+        PAUSE_HEIGHT = FINAL_HEIGHT - 40
+
+        self.log.info("Restarting node to stop at height %d", PAUSE_HEIGHT)
+        self.restart_node(1, extra_args=[
+            f"-stopatheight={PAUSE_HEIGHT}", *self.extra_args[1]])
+
+        # Finally connect the nodes and let them sync.
+        self.connect_nodes(0, 1)
+
+        n1.wait_until_stopped(timeout=5)
+
+        self.log.info("Checking that blocks are segmented on disk")
+        assert self.has_blockfile(n1, "00000"), "normal blockfile missing"
+        assert self.has_blockfile(n1, "00001"), "assumed blockfile missing"
+        assert not self.has_blockfile(n1, "00002"), "too many blockfiles"
+
+        self.log.info("Restarted node before snapshot validation completed, reloading...")
+        self.restart_node(1, extra_args=self.extra_args[1])
+        self.connect_nodes(0, 1)
+
+        self.log.info(f"Ensuring snapshot chain syncs to tip. ({FINAL_HEIGHT})")
+        wait_until_helper(lambda: n1.getchainstates()['snapshot']['blocks'] == FINAL_HEIGHT)
+        self.sync_blocks(nodes=(n0, n1))
+
+        self.log.info("Ensuring background validation completes")
+        # N.B.: the `snapshot` key disappears once the background validation is complete.
+        wait_until_helper(lambda: not n1.getchainstates().get('snapshot'))
+
+        # Ensure indexes have synced.
+        completed_idx_state = {
+            'basic block filter index': COMPLETE_IDX,
+            'coinstatsindex': COMPLETE_IDX,
+        }
+        self.wait_until(lambda: n1.getindexinfo() == completed_idx_state)
+
+
+        for i in (0, 1):
+            n = self.nodes[i]
+            self.log.info(f"Restarting node {i} to ensure (Check|Load)BlockIndex passes")
+            self.restart_node(i, extra_args=self.extra_args[i])
+
+            assert_equal(n.getblockchaininfo()["blocks"], FINAL_HEIGHT)
+
+            assert_equal(n.getchainstates()['normal']['blocks'], FINAL_HEIGHT)
+            assert_equal(n.getchainstates().get('snapshot'), None)
+
+            if i != 0:
+                # Ensure indexes have synced for the assumeutxo node
+                self.wait_until(lambda: n.getindexinfo() == completed_idx_state)
+
+
+        # Node 2: all indexes + reindex
+        # -----------------------------
+
+        self.log.info("-- Testing all indexes + reindex")
+        assert_equal(n2.getblockcount(), START_HEIGHT)
+
+        self.log.info(f"Loading snapshot into third node from {dump_output['path']}")
+        loaded = n2.loadtxoutset(dump_output['path'])
+        assert_equal(loaded['coins_loaded'], SNAPSHOT_BASE_HEIGHT)
+        assert_equal(loaded['base_height'], SNAPSHOT_BASE_HEIGHT)
+
+        monitor = n2.getchainstates()
+        assert_equal(monitor['normal']['blocks'], START_HEIGHT)
+        assert_equal(monitor['snapshot']['blocks'], SNAPSHOT_BASE_HEIGHT)
+        assert_equal(monitor['snapshot']['snapshot_blockhash'], dump_output['base_hash'])
+
+        self.connect_nodes(0, 2)
+        wait_until_helper(lambda: n2.getchainstates()['snapshot']['blocks'] == FINAL_HEIGHT)
+        self.sync_blocks()
+
+        self.log.info("Ensuring background validation completes")
+        wait_until_helper(lambda: not n2.getchainstates().get('snapshot'))
+
+        completed_idx_state = {
+            'basic block filter index': COMPLETE_IDX,
+            'coinstatsindex': COMPLETE_IDX,
+            'txindex': COMPLETE_IDX,
+        }
+        self.wait_until(lambda: n2.getindexinfo() == completed_idx_state)
+
+        for i in (0, 2):
+            n = self.nodes[i]
+            self.log.info(f"Restarting node {i} to ensure (Check|Load)BlockIndex passes")
+            self.restart_node(i, extra_args=self.extra_args[i])
+
+            assert_equal(n.getblockchaininfo()["blocks"], FINAL_HEIGHT)
+
+            assert_equal(n.getchainstates()['normal']['blocks'], FINAL_HEIGHT)
+            assert_equal(n.getchainstates().get('snapshot'), None)
+
+            if i != 0:
+                # Ensure indexes have synced for the assumeutxo node
+                self.wait_until(lambda: n.getindexinfo() == completed_idx_state)
+
+        self.log.info("Test -reindex-chainstate of an assumeutxo-synced node")
+        self.restart_node(2, extra_args=[
+            '-reindex-chainstate=1', *self.extra_args[2]])
+        assert_equal(n2.getblockchaininfo()["blocks"], FINAL_HEIGHT)
+        wait_until_helper(lambda: n2.getblockcount() == FINAL_HEIGHT)
+
+        self.log.info("Test -reindex of an assumeutxo-synced node")
+        self.restart_node(2, extra_args=['-reindex=1', *self.extra_args[2]])
+        self.connect_nodes(0, 2)
+        wait_until_helper(lambda: n2.getblockcount() == FINAL_HEIGHT)
+
+
+if __name__ == '__main__':
+    AssumeutxoTest().main()
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index 73e7516ea7..73635b4397 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -979,3 +979,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
     def is_bdb_compiled(self):
         """Checks whether the wallet module was compiled with BDB support."""
         return self.config["components"].getboolean("USE_BDB")
+
+    def has_blockfile(self, node, filenum: str):
+        blocksdir = os.path.join(node.datadir, self.chain, 'blocks', '')
+        return os.path.isfile(os.path.join(blocksdir, f"blk{filenum}.dat"))
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 32aee3aa80..9a0b5c6f0a 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -324,6 +324,7 @@ BASE_SCRIPTS = [
     'wallet_coinbase_category.py --descriptors',
     'feature_filelock.py',
     'feature_loadblock.py',
+    'feature_assumeutxo.py',
     'p2p_dos_header_tree.py',
     'p2p_add_connections.py',
     'feature_bind_port_discover.py',