Repository: bitcoin/bitcoin
File: test/functional/feature_assumeutxo.py (Python)

Code before:
    def test_invalid_file_path(self):
        self.log.info("Test bitcoind should fail when file path is invalid.")
        node = self.nodes[0]
        path = node.datadir_path / node.chain / "invalid" / "path"
        assert_raises_rpc_error(-8, "Couldn't open file {} for reading.".format(path), node.loadtxoutset, path)

    def test_snapshot_with_less_work(self, dump_output_path):
        self.log.info("Test bitcoind should fail when snapshot has less accumulated work than this node.")
        node = self.nodes[0]
        assert_equal(node.getblockcount(), FINAL_HEIGHT)
        with node.assert_debug_log(expected_msgs=["[snapshot] activation failed - work does not exceed active chainstate"]):
            assert_raises_rpc_error(-32603, "Unable to load UTXO snapshot", node.loadtxoutset, dump_output_path)

    def test_snapshot_block_invalidated(self, dump_output_path):
        self.log.info("Test snapshot is not loaded when base block is invalid.")
        node = self.nodes[0]
        # We are testing the case where the base block is invalidated itself
        # and also the case where one of its parents is invalidated.
        for height in [SNAPSHOT_BASE_HEIGHT, SNAPSHOT_BASE_HEIGHT - 1]:
            block_hash = node.getblockhash(height)
            node.invalidateblock(block_hash)
            assert_equal(node.getblockcount(), height - 1)
            msg = "Unable to load UTXO snapshot: The base block header (3bb7ce5eba0be48939b7a521ac1ba9316afee2c7bada3a0cca24188e6d7d96c0) is part of an invalid chain."
            assert_raises_rpc_error(-32603, msg, node.loadtxoutset, dump_output_path)
            node.reconsiderblock(block_hash)

    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]

        self.mini_wallet = MiniWallet(n0)

        # Mock time for a deterministic chain
        for n in self.nodes:
            n.setmocktime(n.getblockheader(n.getbestblockhash())['time'])

        # Generate a series of blocks that `n0` will have in the snapshot,
        # but that n1 and n2 don't yet see.
        assert n0.getblockcount() == START_HEIGHT
        blocks = {START_HEIGHT: Block(n0.getbestblockhash(), 1, START_HEIGHT + 1)}
        for i in range(100):
            block_tx = 1
            if i % 3 == 0:

Review comment (suggestion):
Got to know from the CPP code that `-reindex-chainstate` will load up from the blk.dat files. That's why I understand only 2 more blocks are needed to exceed the work of the snapshot chain.

Code after:
        node = self.nodes[0]
        path = node.datadir_path / node.chain / "invalid" / "path"
        assert_raises_rpc_error(-8, "Couldn't open file {} for reading.".format(path), node.loadtxoutset, path)

    def test_snapshot_with_less_work(self, dump_output_path):
        self.log.info("Test bitcoind should fail when snapshot has less accumulated work than this node.")
        node = self.nodes[0]
        assert_equal(node.getblockcount(), FINAL_HEIGHT)
        with node.assert_debug_log(expected_msgs=["[snapshot] activation failed - work does not exceed active chainstate"]):
            assert_raises_rpc_error(-32603, "Unable to load UTXO snapshot", node.loadtxoutset, dump_output_path)
        self.restart_node(0, extra_args=self.extra_args[0])

    def test_snapshot_in_a_divergent_chain(self, dump_output_path):
        n0 = self.nodes[0]
        n3 = self.nodes[3]
        assert_equal(n0.getblockcount(), FINAL_HEIGHT)
        assert_equal(n3.getblockcount(), START_HEIGHT)

        self.log.info("Check importing a snapshot where current chain-tip is not an ancestor of the snapshot block but has less work")
        # Generate a divergent chain in n3 up to 298
        self.generate(n3, nblocks=99, sync_fun=self.no_op)
        assert_equal(n3.getblockcount(), SNAPSHOT_BASE_HEIGHT - 1)

        # Try importing the snapshot and assert its success
        loaded = n3.loadtxoutset(dump_output_path)
        assert_equal(loaded['base_height'], SNAPSHOT_BASE_HEIGHT)
        normal, snapshot = n3.getchainstates()["chainstates"]
        assert_equal(normal['blocks'], START_HEIGHT + 99)
        assert_equal(snapshot['blocks'], SNAPSHOT_BASE_HEIGHT)

        # Now lets sync the nodes and wait for the background validation to finish
        self.connect_nodes(0, 3)
        self.sync_blocks(nodes=(n0, n3))
        self.wait_until(lambda: len(n3.getchainstates()['chainstates']) == 1)

    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]
        n3 = self.nodes[3]

        self.mini_wallet = MiniWallet(n0)

        # Mock time for a deterministic chain