test_framework.py

#!/usr/bin/env python3
# Copyright (c) 2014-2019 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Base class for RPC testing."""

import configparser
from enum import Enum
import argparse
import logging
import os
import pdb
import random
import re
import shutil
import subprocess
import sys
import tempfile
import time

from .authproxy import JSONRPCException
from . import coverage
from .test_node import TestNode
from .mininode import NetworkThread
from .util import (
    MAX_NODES,
    PortSeed,
    assert_equal,
    check_json_precision,
    connect_nodes,
    disconnect_nodes,
    get_datadir_path,
    initialize_datadir,
    sync_blocks,
    sync_mempools,
)


class TestStatus(Enum):
    PASSED = 1
    FAILED = 2
    SKIPPED = 3

TEST_EXIT_PASSED = 0
TEST_EXIT_FAILED = 1
TEST_EXIT_SKIPPED = 77

TMPDIR_PREFIX = "bitcoin_func_test_"


class SkipTest(Exception):
    """This exception is raised to skip a test"""

    def __init__(self, message):
        self.message = message


class BitcoinTestMetaClass(type):
    """Metaclass for BitcoinTestFramework.

    Ensures that any attempt to register a subclass of `BitcoinTestFramework`
    adheres to a standard whereby the subclass overrides `set_test_params` and
    `run_test` but DOES NOT override either `__init__` or `main`. If any of
    those standards are violated, a ``TypeError`` is raised."""

    def __new__(cls, clsname, bases, dct):
        if not clsname == 'BitcoinTestFramework':
            if not ('run_test' in dct and 'set_test_params' in dct):
                raise TypeError("BitcoinTestFramework subclasses must override "
                                "'run_test' and 'set_test_params'")
            if '__init__' in dct or 'main' in dct:
                raise TypeError("BitcoinTestFramework subclasses may not override "
                                "'__init__' or 'main'")

        return super().__new__(cls, clsname, bases, dct)


class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
    """Base class for a bitcoin test script.

    Individual bitcoin test scripts should subclass this class and override the set_test_params() and run_test() methods.

    Individual tests can also override the following methods to customize the test setup:

    - add_options()
    - setup_chain()
    - setup_network()
    - setup_nodes()

    The __init__() and main() methods should not be overridden.

    This class also contains various public and private helper methods."""

    def __init__(self):
        """Sets test framework defaults. Do not override this method. Instead, override the set_test_params() method"""
        self.chain = 'regtest'
        self.setup_clean_chain = False
        self.nodes = []
        self.network_thread = None
        self.rpc_timeout = 60  # Wait for up to 60 seconds for the RPC server to respond
        self.supports_cli = True
        self.bind_to_localhost_only = True
        self.set_test_params()
        self.parse_args()
        if self.options.timeout_factor == 0 :
            self.options.timeout_factor = 99999
        self.rpc_timeout = int(self.rpc_timeout * self.options.timeout_factor) # optionally, increase timeout by a factor

    def main(self):
        """Main function. This should not be overridden by the subclass test scripts."""

        assert hasattr(self, "num_nodes"), "Test must set self.num_nodes in set_test_params()"

        try:
            self.setup()
            self.run_test()
        except JSONRPCException:
            self.log.exception("JSONRPC error")
            self.success = TestStatus.FAILED
        except SkipTest as e:
            self.log.warning("Test Skipped: %s" % e.message)
            self.success = TestStatus.SKIPPED
        except AssertionError:
            self.log.exception("Assertion failed")
            self.success = TestStatus.FAILED
        except KeyError:
            self.log.exception("Key error")
            self.success = TestStatus.FAILED
        except subprocess.CalledProcessError as e:
            self.log.exception("Called Process failed with '{}'".format(e.output))
            self.success = TestStatus.FAILED
        except Exception:
            self.log.exception("Unexpected exception caught during testing")
            self.success = TestStatus.FAILED
        except KeyboardInterrupt:
            self.log.warning("Exiting after keyboard interrupt")
            self.success = TestStatus.FAILED
        finally:
            exit_code = self.shutdown()
            sys.exit(exit_code)

    def parse_args(self):
        parser = argparse.ArgumentParser(usage="%(prog)s [options]")
        parser.add_argument("--nocleanup", dest="nocleanup", default=False, action="store_true",
                            help="Leave bitcoinds and test.* datadir on exit or error")
        parser.add_argument("--noshutdown", dest="noshutdown", default=False, action="store_true",
                            help="Don't stop bitcoinds after the test execution")
        parser.add_argument("--cachedir", dest="cachedir", default=os.path.abspath(os.path.dirname(os.path.realpath(__file__)) + "/../../cache"),
                            help="Directory for caching pregenerated datadirs (default: %(default)s)")
        parser.add_argument("--tmpdir", dest="tmpdir", help="Root directory for datadirs")
        parser.add_argument("-l", "--loglevel", dest="loglevel", default="INFO",
                            help="log events at this level and higher to the console. Can be set to DEBUG, INFO, WARNING, ERROR or CRITICAL. Passing --loglevel DEBUG will output all logs to console. Note that logs at all levels are always written to the test_framework.log file in the temporary test directory.")
        parser.add_argument("--tracerpc", dest="trace_rpc", default=False, action="store_true",
                            help="Print out all RPC calls as they are made")
        parser.add_argument("--portseed", dest="port_seed", default=os.getpid(), type=int,
                            help="The seed to use for assigning port numbers (default: current process id)")
        parser.add_argument("--coveragedir", dest="coveragedir",
                            help="Write tested RPC commands into this directory")
        parser.add_argument("--configfile", dest="configfile",
                            default=os.path.abspath(os.path.dirname(os.path.realpath(__file__)) + "/../../config.ini"),
                            help="Location of the test framework config file (default: %(default)s)")
        parser.add_argument("--pdbonfailure", dest="pdbonfailure", default=False, action="store_true",
                            help="Attach a python debugger if test fails")
        parser.add_argument("--usecli", dest="usecli", default=False, action="store_true",
                            help="use bitcoin-cli instead of RPC for all commands")
        parser.add_argument("--perf", dest="perf", default=False, action="store_true",
                            help="profile running nodes with perf for the duration of the test")
        parser.add_argument("--valgrind", dest="valgrind", default=False, action="store_true",
                            help="run nodes under the valgrind memory error detector: expect at least a ~10x slowdown, valgrind 3.14 or later required")
        parser.add_argument("--randomseed", type=int,
                            help="set a random seed for deterministically reproducing a previous test run")
        parser.add_argument("--descriptors", default=False, action="store_true",
                            help="Run test using a descriptor wallet")
        parser.add_argument('--timeout-factor', dest="timeout_factor", type=float, default=1.0, help='adjust test timeouts by a factor. Setting it to 0 disables all timeouts')
        self.add_options(parser)
        self.options = parser.parse_args()

    def setup(self):
        """Call this method to start up the test framework object with options set."""

        PortSeed.n = self.options.port_seed

        check_json_precision()

        self.options.cachedir = os.path.abspath(self.options.cachedir)

        config = configparser.ConfigParser()
        config.read_file(open(self.options.configfile))
        self.config = config
        fname_bitcoind = os.path.join(
            config["environment"]["BUILDDIR"],
            "src",
            "bitcoind" + config["environment"]["EXEEXT"]
        )
        fname_bitcoincli = os.path.join(
            config["environment"]["BUILDDIR"],
            "src",
            "bitcoin-cli" + config["environment"]["EXEEXT"]
        )
        self.options.bitcoind = os.getenv("BITCOIND", default=fname_bitcoind)
        self.options.bitcoincli = os.getenv("BITCOINCLI", default=fname_bitcoincli)

        self.options.previous_releases_path = os.getenv("PREVIOUS_RELEASES_DIR") or os.getcwd() + "/releases"

        os.environ['PATH'] = os.pathsep.join([
            os.path.join(config['environment']['BUILDDIR'], 'src'),
            os.path.join(config['environment']['BUILDDIR'], 'src', 'qt'), os.environ['PATH']
        ])

        # Set up temp directory and start logging
        if self.options.tmpdir:
            self.options.tmpdir = os.path.abspath(self.options.tmpdir)
            os.makedirs(self.options.tmpdir, exist_ok=False)
        else:
            self.options.tmpdir = tempfile.mkdtemp(prefix=TMPDIR_PREFIX)
        self._start_logging()

        # Seed the PRNG. Note that test runs are reproducible if and only if
        # a single thread accesses the PRNG. For more information, see
        # https://docs.python.org/3/library/random.html#notes-on-reproducibility.
        # The network thread shouldn't access random. If we need to change the
        # network thread to access randomness, it should instantiate its own
        # random.Random object.
        seed = self.options.randomseed

        if seed is None:
            seed = random.randrange(sys.maxsize)
        else:
            self.log.debug("User supplied random seed {}".format(seed))

        random.seed(seed)
        self.log.debug("PRNG seed is: {}".format(seed))

        self.log.debug('Setting up network thread')
        self.network_thread = NetworkThread()
        self.network_thread.start()

        if self.options.usecli:
            if not self.supports_cli:
                raise SkipTest("--usecli specified but test does not support using CLI")
            self.skip_if_no_cli()
        self.skip_test_if_missing_module()
        self.setup_chain()
        self.setup_network()

        self.success = TestStatus.PASSED

    def shutdown(self):
        """Call this method to shut down the test framework object."""

        if self.success == TestStatus.FAILED and self.options.pdbonfailure:
            print("Testcase failed. Attaching python debugger. Enter ? for help")
            pdb.set_trace()

        self.log.debug('Closing down network thread')
        self.network_thread.close()
        if not self.options.noshutdown:
            self.log.info("Stopping nodes")
            if self.nodes:
                self.stop_nodes()
        else:
            for node in self.nodes:
                node.cleanup_on_exit = False
            self.log.info("Note: bitcoinds were not stopped and may still be running")

        should_clean_up = (
            not self.options.nocleanup and
            not self.options.noshutdown and
            self.success != TestStatus.FAILED and
            not self.options.perf
        )
        if should_clean_up:
            self.log.info("Cleaning up {} on exit".format(self.options.tmpdir))
            cleanup_tree_on_exit = True
        elif self.options.perf:
            self.log.warning("Not cleaning up dir {} due to perf data".format(self.options.tmpdir))
            cleanup_tree_on_exit = False
        else:
            self.log.warning("Not cleaning up dir {}".format(self.options.tmpdir))
            cleanup_tree_on_exit = False

        if self.success == TestStatus.PASSED:
            self.log.info("Tests successful")
            exit_code = TEST_EXIT_PASSED
        elif self.success == TestStatus.SKIPPED:
            self.log.info("Test skipped")
            exit_code = TEST_EXIT_SKIPPED
        else:
            self.log.error("Test failed. Test logging available at %s/test_framework.log", self.options.tmpdir)
            self.log.error("Hint: Call {} '{}' to consolidate all logs".format(os.path.normpath(os.path.dirname(os.path.realpath(__file__)) + "/../combine_logs.py"), self.options.tmpdir))
            exit_code = TEST_EXIT_FAILED
        # Logging.shutdown will not remove stream- and filehandlers, so we must
        # do it explicitly. Handlers are removed so the next test run can apply
        # different log handler settings.
        # See: https://docs.python.org/3/library/logging.html#logging.shutdown
        for h in list(self.log.handlers):
            h.flush()
            h.close()
            self.log.removeHandler(h)
        rpc_logger = logging.getLogger("BitcoinRPC")
        for h in list(rpc_logger.handlers):
            h.flush()
            rpc_logger.removeHandler(h)
        if cleanup_tree_on_exit:
            shutil.rmtree(self.options.tmpdir)

        self.nodes.clear()
        return exit_code

    # Methods to override in subclass test scripts.
    def set_test_params(self):
        """Tests must this method to change default values for number of nodes, topology, etc"""
        raise NotImplementedError

    def add_options(self, parser):
        """Override this method to add command-line options to the test"""
        pass

    def skip_test_if_missing_module(self):
        """Override this method to skip a test if a module is not compiled"""
        pass

    def setup_chain(self):
        """Override this method to customize blockchain setup"""
        self.log.info("Initializing test directory " + self.options.tmpdir)
        if self.setup_clean_chain:
            self._initialize_chain_clean()
        else:
            self._initialize_chain()

    def setup_network(self):
        """Override this method to customize test network topology"""
        self.setup_nodes()

        # Connect the nodes as a "chain".  This allows us
        # to split the network between nodes 1 and 2 to get
        # two halves that can work on competing chains.
        #
        # Topology looks like this:
        # node0 <-- node1 <-- node2 <-- node3
        #
        # If all nodes are in IBD (clean chain from genesis), node0 is assumed to be the source of blocks (miner). To
        # ensure block propagation, all nodes will establish outgoing connections toward node0.
        # See fPreferredDownload in net_processing.
        #
        # If further outbound connections are needed, they can be added at the beginning of the test with e.g.
        # connect_nodes(self.nodes[1], 2)
        for i in range(self.num_nodes - 1):
            connect_nodes(self.nodes[i + 1], i)
        self.sync_all()

    def setup_nodes(self):
        """Override this method to customize test node setup"""
        extra_args = [[]] * self.num_nodes
        wallets = [[]] * self.num_nodes
        if hasattr(self, "extra_args"):
            extra_args = self.extra_args
            wallets = [[x for x in eargs if x.startswith('-wallet=')] for eargs in extra_args]
        extra_args = [x + ['-nowallet'] for x in extra_args]
        self.add_nodes(self.num_nodes, extra_args)
        self.start_nodes()
        for i, n in enumerate(self.nodes):
            n.extra_args.pop()
            if '-wallet=0' in n.extra_args or '-nowallet' in n.extra_args or '-disablewallet' in n.extra_args or not self.is_wallet_compiled():
                continue
            if '-wallet=' not in wallets[i] and not any([x.startswith('-wallet=') for x in wallets[i]]):
                wallets[i].append('-wallet=')
            for w in wallets[i]:
                wallet_name = w.split('=', 1)[1]
                n.createwallet(wallet_name=wallet_name, descriptors=self.options.descriptors)
        self.import_deterministic_coinbase_privkeys()
        if not self.setup_clean_chain:
            for n in self.nodes:
                assert_equal(n.getblockchaininfo()["blocks"], 199)
            # To ensure that all nodes are out of IBD, the most recent block
            # must have a timestamp not too old (see IsInitialBlockDownload()).
            self.log.debug('Generate a block with current time')
            block_hash = self.nodes[0].generate(1)[0]
            block = self.nodes[0].getblock(blockhash=block_hash, verbosity=0)
            for n in self.nodes:
                n.submitblock(block)
                chain_info = n.getblockchaininfo()
                assert_equal(chain_info["blocks"], 200)
                assert_equal(chain_info["initialblockdownload"], False)

    def import_deterministic_coinbase_privkeys(self):
        for n in self.nodes:
            try:
                n.getwalletinfo()
            except JSONRPCException as e:
                assert str(e).startswith('Method not found')
                continue

            n.importprivkey(privkey=n.get_deterministic_priv_key().key, label='coinbase')

    def run_test(self):
        """Tests must override this method to define test logic"""
        raise NotImplementedError

    # 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, binary_cli=None, versions=None):
        """Instantiate TestNode objects.

        Should only be called once after the nodes have been specified in
        set_test_params()."""
        def get_bin_from_version(version, bin_name, bin_default):
            if not version:
                return bin_default
            return os.path.join(
                self.options.previous_releases_path,
                re.sub(
                    r'\.0$',
                    '',  # remove trailing .0 for point releases
                    'v{}.{}.{}.{}'.format(
                        (version % 100000000) // 1000000,
                        (version % 1000000) // 10000,
                        (version % 10000) // 100,
                        (version % 100) // 1,
                    ),
                ),
                'bin',
                bin_name,
            )

        if self.bind_to_localhost_only:
            extra_confs = [["bind=127.0.0.1"]] * num_nodes
        else:
            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 = [get_bin_from_version(v, 'bitcoind', self.options.bitcoind) for v in versions]
        if binary_cli is None:
            binary_cli = [get_bin_from_version(v, 'bitcoin-cli', self.options.bitcoincli) for v in versions]
        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,
                get_datadir_path(self.options.tmpdir, i),
                chain=self.chain,
                rpchost=rpchost,
                timewait=self.rpc_timeout,
                timeout_factor=self.options.timeout_factor,
                bitcoind=binary[i],
                bitcoin_cli=binary_cli[i],
                version=versions[i],
                coverage_dir=self.options.coveragedir,
                cwd=self.options.tmpdir,
                extra_conf=extra_confs[i],
                extra_args=extra_args[i],
                use_cli=self.options.usecli,
                start_perf=self.options.perf,
                use_valgrind=self.options.valgrind,
                descriptors=self.options.descriptors,
            ))

    def start_node(self, i, *args, **kwargs):
        """Start a bitcoind"""

        node = self.nodes[i]

        node.start(*args, **kwargs)
        node.wait_for_rpc_connection()

        if self.options.coveragedir is not None:
            coverage.write_all_rpc_commands(self.options.coveragedir, node.rpc)

    def start_nodes(self, extra_args=None, *args, **kwargs):
        """Start multiple bitcoinds"""

        if extra_args is None:
            extra_args = [None] * self.num_nodes
        assert_equal(len(extra_args), self.num_nodes)
        try:
            for i, node in enumerate(self.nodes):
                node.start(extra_args[i], *args, **kwargs)
            for node in self.nodes:
                node.wait_for_rpc_connection()
        except:
            # If one node failed to start, stop the others
            self.stop_nodes()
            raise

        if self.options.coveragedir is not None:
            for node in self.nodes:
                coverage.write_all_rpc_commands(self.options.coveragedir, node.rpc)

    def stop_node(self, i, expected_stderr='', wait=0):
        """Stop a bitcoind test node"""
        self.nodes[i].stop_node(expected_stderr, wait=wait)
        self.nodes[i].wait_until_stopped()

    def stop_nodes(self, wait=0):
        """Stop multiple bitcoind test nodes"""
        for node in self.nodes:
            # Issue RPC to stop nodes
            node.stop_node(wait=wait)

        for node in self.nodes:
            # Wait for nodes to stop
            node.wait_until_stopped()

    def restart_node(self, i, extra_args=None):
        """Stop and start a test node"""
        self.stop_node(i)
        self.start_node(i, extra_args)

    def wait_for_node_exit(self, i, timeout):
        self.nodes[i].process.wait(timeout)

    def split_network(self):
        """
        Split the network of four nodes into nodes 0/1 and 2/3.
        """
        disconnect_nodes(self.nodes[1], 2)
        disconnect_nodes(self.nodes[2], 1)
        self.sync_all(self.nodes[:2])
        self.sync_all(self.nodes[2:])

    def join_network(self):
        """
        Join the (previously split) network halves together.
        """
        connect_nodes(self.nodes[1], 2)
        self.sync_all()

    def sync_blocks(self, nodes=None, **kwargs):
        sync_blocks(nodes or self.nodes, **kwargs)

    def sync_mempools(self, nodes=None, **kwargs):
        sync_mempools(nodes or self.nodes, **kwargs)

    def sync_all(self, nodes=None, **kwargs):
        self.sync_blocks(nodes, **kwargs)
        self.sync_mempools(nodes, **kwargs)

    # Private helper methods. These should not be accessed by the subclass test scripts.

    def _start_logging(self):
        # Add logger and logging handlers
        self.log = logging.getLogger('TestFramework')
        self.log.setLevel(logging.DEBUG)
        # Create file handler to log all messages
        fh = logging.FileHandler(self.options.tmpdir + '/test_framework.log', encoding='utf-8')
        fh.setLevel(logging.DEBUG)
        # Create console handler to log messages to stderr. By default this logs only error messages, but can be configured with --loglevel.
        ch = logging.StreamHandler(sys.stdout)
        # User can provide log level as a number or string (eg DEBUG). loglevel was caught as a string, so try to convert it to an int
        ll = int(self.options.loglevel) if self.options.loglevel.isdigit() else self.options.loglevel.upper()
        ch.setLevel(ll)
        # Format logs the same as bitcoind's debug.log with microprecision (so log files can be concatenated and sorted)
        formatter = logging.Formatter(fmt='%(asctime)s.%(msecs)03d000Z %(name)s (%(levelname)s): %(message)s', datefmt='%Y-%m-%dT%H:%M:%S')
        formatter.converter = time.gmtime
        fh.setFormatter(formatter)
        ch.setFormatter(formatter)
        # add the handlers to the logger
        self.log.addHandler(fh)
        self.log.addHandler(ch)

        if self.options.trace_rpc:
            rpc_logger = logging.getLogger("BitcoinRPC")
            rpc_logger.setLevel(logging.DEBUG)
            rpc_handler = logging.StreamHandler(sys.stdout)
            rpc_handler.setLevel(logging.DEBUG)
            rpc_logger.addHandler(rpc_handler)

    def _initialize_chain(self):
        """Initialize a pre-mined blockchain for use by the test.

        Create a cache of a 199-block-long chain
        Afterward, create num_nodes copies from the cache."""

        CACHE_NODE_ID = 0  # Use node 0 to create the cache for all other nodes
        cache_node_dir = get_datadir_path(self.options.cachedir, CACHE_NODE_ID)
        assert self.num_nodes <= MAX_NODES

        if not os.path.isdir(cache_node_dir):
            self.log.debug("Creating cache directory {}".format(cache_node_dir))

            initialize_datadir(self.options.cachedir, CACHE_NODE_ID, self.chain)
            self.nodes.append(
                TestNode(
                    CACHE_NODE_ID,
                    cache_node_dir,
                    chain=self.chain,
                    extra_conf=["bind=127.0.0.1"],
                    extra_args=['-disablewallet'],
                    rpchost=None,
                    timewait=self.rpc_timeout,
                    timeout_factor=self.options.timeout_factor,
                    bitcoind=self.options.bitcoind,
                    bitcoin_cli=self.options.bitcoincli,
                    coverage_dir=None,
                    cwd=self.options.tmpdir,
                    descriptors=self.options.descriptors,
                ))
            self.start_node(CACHE_NODE_ID)
            cache_node = self.nodes[CACHE_NODE_ID]

            # Wait for RPC connections to be ready
            cache_node.wait_for_rpc_connection()

            # Set a time in the past, so that blocks don't end up in the future
            cache_node.setmocktime(cache_node.getblockheader(cache_node.getbestblockhash())['time'])

            # Create a 199-block-long chain; each of the 4 first nodes
            # gets 25 mature blocks and 25 immature.
            # The 4th node gets only 24 immature blocks so that the very last
            # block in the cache does not age too much (have an old tip age).
            # This is needed so that we are out of IBD when the test starts,
            # see the tip age check in IsInitialBlockDownload().
            for i in range(8):
                cache_node.generatetoaddress(
                    nblocks=25 if i != 7 else 24,
                    address=TestNode.PRIV_KEYS[i % 4].address,
                )

            assert_equal(cache_node.getblockchaininfo()["blocks"], 199)

            # Shut it down, and clean up cache directories:
            self.stop_nodes()
            self.nodes = []

            def cache_path(*paths):
                return os.path.join(cache_node_dir, self.chain, *paths)

            os.rmdir(cache_path('wallets'))  # Remove empty wallets dir
            for entry in os.listdir(cache_path()):
                if entry not in ['chainstate', 'blocks']:  # Only keep chainstate and blocks folder
                    os.remove(cache_path(entry))

        for i in range(self.num_nodes):
            self.log.debug("Copy cache directory {} to node {}".format(cache_node_dir, i))
            to_dir = get_datadir_path(self.options.tmpdir, i)
            shutil.copytree(cache_node_dir, to_dir)
            initialize_datadir(self.options.tmpdir, i, self.chain)  # Overwrite port/rpcport in bitcoin.conf

    def _initialize_chain_clean(self):
        """Initialize empty blockchain for use by the test.

        Create an empty blockchain and num_nodes wallets.
        Useful if a test case wants complete control over initialization."""
        for i in range(self.num_nodes):
            initialize_datadir(self.options.tmpdir, i, self.chain)

    def skip_if_no_py3_zmq(self):
        """Attempt to import the zmq package and skip the test if the import fails."""
        try:
            import zmq  # noqa
        except ImportError:
            raise SkipTest("python3-zmq module not available.")

    def skip_if_no_bitcoind_zmq(self):
        """Skip the running test if bitcoind has not been compiled with zmq support."""
        if not self.is_zmq_compiled():
            raise SkipTest("bitcoind has not been built with zmq enabled.")

    def skip_if_no_wallet(self):
        """Skip the running test if wallet has not been compiled."""
        if not self.is_wallet_compiled():
            raise SkipTest("wallet has not been compiled.")

    def skip_if_no_wallet_tool(self):
        """Skip the running test if bitcoin-wallet has not been compiled."""
        if not self.is_wallet_tool_compiled():
            raise SkipTest("bitcoin-wallet has not been compiled")

    def skip_if_no_cli(self):
        """Skip the running test if bitcoin-cli has not been compiled."""
        if not self.is_cli_compiled():
            raise SkipTest("bitcoin-cli has not been compiled.")

    def skip_if_no_previous_releases(self):
        """Skip the running test if previous releases are not available."""
        if not self.has_previous_releases():
            raise SkipTest("previous releases not available or disabled")

    def has_previous_releases(self):
        """Checks whether previous releases are present and enabled."""
        if os.getenv("TEST_PREVIOUS_RELEASES") == "false":
            # disabled
            return False

        if not os.path.isdir(self.options.previous_releases_path):
            if os.getenv("TEST_PREVIOUS_RELEASES") == "true":
                raise AssertionError("TEST_PREVIOUS_RELEASES=true but releases missing: {}".format(
                    self.options.previous_releases_path))
            # missing
            return False
        return True

    def is_cli_compiled(self):
        """Checks whether bitcoin-cli was compiled."""
        return self.config["components"].getboolean("ENABLE_CLI")

    def is_wallet_compiled(self):
        """Checks whether the wallet module was compiled."""
        return self.config["components"].getboolean("ENABLE_WALLET")

    def is_wallet_tool_compiled(self):
        """Checks whether bitcoin-wallet was compiled."""
        return self.config["components"].getboolean("ENABLE_WALLET_TOOL")

    def is_zmq_compiled(self):
        """Checks whether the zmq module was compiled."""
        return self.config["components"].getboolean("ENABLE_ZMQ")