config.py

from __future__ import print_function

import argparse
import itertools
import os
import random
import re
import shlex
import string
import sys
import warnings
from fnmatch import fnmatchcase
from subprocess import list2cmdline

import pkg_resources
import pluggy
import py
from packaging.version import parse

import tox
from tox.interpreters import Interpreters

hookimpl = tox.hookimpl
"""DEPRECATED - REMOVE - this is left for compatibility with plugins importing this from here.

Instead create a hookimpl in your code with:

    import pluggy
    hookimpl = pluggy.HookimplMarker("tox")
"""

default_factors = tox.PYTHON.DEFAULT_FACTORS
"""DEPRECATED MOVE - please update to new location."""


def get_plugin_manager(plugins=()):
    # initialize plugin manager
    import tox.venv

    pm = pluggy.PluginManager("tox")
    pm.add_hookspecs(tox.hookspecs)
    pm.register(tox.config)
    pm.register(tox.interpreters)
    pm.register(tox.venv)
    pm.register(tox.session)
    pm.load_setuptools_entrypoints("tox")
    for plugin in plugins:
        pm.register(plugin)
    pm.check_pending()
    return pm


class Parser:
    """Command line and ini-parser control object."""

    def __init__(self):
        self.argparser = argparse.ArgumentParser(description="tox options", add_help=False)
        self._testenv_attr = []

    def add_argument(self, *args, **kwargs):
        """ add argument to command line parser.  This takes the
        same arguments that ``argparse.ArgumentParser.add_argument``.
        """
        return self.argparser.add_argument(*args, **kwargs)

    def add_testenv_attribute(self, name, type, help, default=None, postprocess=None):
        """ add an ini-file variable for "testenv" section.

        Types are specified as strings like "bool", "line-list", "string", "argv", "path",
        "argvlist".

        The ``postprocess`` function will be called for each testenv
        like ``postprocess(testenv_config=testenv_config, value=value)``
        where ``value`` is the value as read from the ini (or the default value)
        and ``testenv_config`` is a :py:class:`tox.config.TestenvConfig` instance
        which will receive all ini-variables as object attributes.

        Any postprocess function must return a value which will then be set
        as the final value in the testenv section.
        """
        self._testenv_attr.append(VenvAttribute(name, type, default, help, postprocess))

    def add_testenv_attribute_obj(self, obj):
        """ add an ini-file variable as an object.

        This works as the ``add_testenv_attribute`` function but expects
        "name", "type", "help", and "postprocess" attributes on the object.
        """
        assert hasattr(obj, "name")
        assert hasattr(obj, "type")
        assert hasattr(obj, "help")
        assert hasattr(obj, "postprocess")
        self._testenv_attr.append(obj)

    def _parse_args(self, args):
        return self.argparser.parse_args(args)

    def _format_help(self):
        return self.argparser.format_help()


class VenvAttribute:
    def __init__(self, name, type, default, help, postprocess):
        self.name = name
        self.type = type
        self.default = default
        self.help = help
        self.postprocess = postprocess


class DepOption:
    name = "deps"
    type = "line-list"
    help = "each line specifies a dependency in pip/setuptools format."
    default = ()

    def postprocess(self, testenv_config, value):
        deps = []
        config = testenv_config.config
        for depline in value:
            m = re.match(r":(\w+):\s*(\S+)", depline)
            if m:
                iname, name = m.groups()
                ixserver = config.indexserver[iname]
            else:
                name = depline.strip()
                ixserver = None
                # we need to process options, in case they contain a space,
                # as the subprocess call to pip install will otherwise fail.
                # in case of a short option, we remove the space
                for option in tox.PIP.INSTALL_SHORT_OPTIONS_ARGUMENT:
                    if name.startswith(option):
                        name = "{}{}".format(option, name[len(option) :].strip())
                # in case of a long option, we add an equal sign
                for option in tox.PIP.INSTALL_LONG_OPTIONS_ARGUMENT:
                    if name.startswith(option + " "):
                        name = "{}={}".format(option, name[len(option) :].strip())
            name = self._replace_forced_dep(name, config)
            deps.append(DepConfig(name, ixserver))
        return deps

    def _replace_forced_dep(self, name, config):
        """Override given dependency config name. Take ``--force-dep-version`` option into account.

        :param name: dep config, for example ["pkg==1.0", "other==2.0"].
        :param config: ``Config`` instance
        :return: the new dependency that should be used for virtual environments
        """
        if not config.option.force_dep:
            return name
        for forced_dep in config.option.force_dep:
            if self._is_same_dep(forced_dep, name):
                return forced_dep
        return name

    @classmethod
    def _is_same_dep(cls, dep1, dep2):
        """Definitions are the same if they refer to the same package, even if versions differ."""
        dep1_name = pkg_resources.Requirement.parse(dep1).project_name
        try:
            dep2_name = pkg_resources.Requirement.parse(dep2).project_name
        except pkg_resources.RequirementParseError:
            # we couldn't parse a version, probably a URL
            return False
        return dep1_name == dep2_name


class PosargsOption:
    name = "args_are_paths"
    type = "bool"
    default = True
    help = "treat positional args in commands as paths"

    def postprocess(self, testenv_config, value):
        config = testenv_config.config
        args = config.option.args
        if args:
            if value:
                args = []
                for arg in config.option.args:
                    if arg:
                        origpath = config.invocationcwd.join(arg, abs=True)
                        if origpath.check():
                            arg = testenv_config.changedir.bestrelpath(origpath)
                    args.append(arg)
            testenv_config._reader.addsubstitutions(args)
        return value


class InstallcmdOption:
    name = "install_command"
    type = "argv"
    default = "pip install {opts} {packages}"
    help = "install command for dependencies and package under test."

    def postprocess(self, testenv_config, value):
        if "{packages}" not in value:
            raise tox.exception.ConfigError(
                "'install_command' must contain '{packages}' substitution"
            )
        return value


def parseconfig(args, plugins=()):
    """Parse the configuration file and create a Config object.

    :param plugins:
    :param list[str] args: list of arguments.
    :rtype: :class:`Config`
    :raise SystemExit: toxinit file is not found
    """
    pm = get_plugin_manager(plugins)
    # prepare command line options
    parser = Parser()
    pm.hook.tox_addoption(parser=parser)
    # parse command line options
    option = parser._parse_args(args)
    interpreters = Interpreters(hook=pm.hook)
    config = Config(pluginmanager=pm, option=option, interpreters=interpreters)
    config._parser = parser
    config._testenv_attr = parser._testenv_attr
    if config.option.version:
        print(get_version_info(pm))
        raise SystemExit(0)
    # parse ini file
    basename = config.option.configfile
    if os.path.isfile(basename):
        inipath = py.path.local(basename)
    elif os.path.isdir(basename):
        # Assume 'tox.ini' filename if directory was passed
        inipath = py.path.local(os.path.join(basename, "tox.ini"))
    else:
        for path in py.path.local().parts(reverse=True):
            inipath = path.join(basename)
            if inipath.check():
                break
        else:
            inipath = py.path.local().join("setup.cfg")
            if not inipath.check():
                helpoptions = option.help or option.helpini
                feedback("toxini file {!r} not found".format(basename), sysexit=not helpoptions)
                if helpoptions:
                    return config

    try:
        parseini(config, inipath)
    except tox.exception.InterpreterNotFound:
        exn = sys.exc_info()[1]
        # Use stdout to match test expectations
        print("ERROR: {}".format(exn))

    # post process config object
    pm.hook.tox_configure(config=config)

    return config


def feedback(msg, sysexit=False):
    print("ERROR: " + msg, file=sys.stderr)
    if sysexit:
        raise SystemExit(1)


def get_version_info(pm):
    out = ["{} imported from {}".format(tox.__version__, tox.__file__)]
    plugin_dist_info = pm.list_plugin_distinfo()
    if plugin_dist_info:
        out.append("registered plugins:")
        for mod, egg_info in plugin_dist_info:
            source = getattr(mod, "__file__", repr(mod))
            out.append("    {}-{} at {}".format(egg_info.project_name, egg_info.version, source))
    return "\n".join(out)


class SetenvDict(object):
    _DUMMY = object()

    def __init__(self, definitions, reader):
        self.definitions = definitions
        self.reader = reader
        self.resolved = {}
        self._lookupstack = []

    def __repr__(self):
        return "{}: {}".format(self.__class__.__name__, self.definitions)

    def __contains__(self, name):
        return name in self.definitions

    def get(self, name, default=None):
        try:
            return self.resolved[name]
        except KeyError:
            try:
                if name in self._lookupstack:
                    raise KeyError(name)
                val = self.definitions[name]
            except KeyError:
                return os.environ.get(name, default)
            self._lookupstack.append(name)
            try:
                self.resolved[name] = res = self.reader._replace(val)
            finally:
                self._lookupstack.pop()
            return res

    def __getitem__(self, name):
        x = self.get(name, self._DUMMY)
        if x is self._DUMMY:
            raise KeyError(name)
        return x

    def keys(self):
        return self.definitions.keys()

    def __setitem__(self, name, value):
        self.definitions[name] = value
        self.resolved[name] = value


@tox.hookimpl
def tox_addoption(parser):
    # formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    parser.add_argument(
        "--version",
        action="store_true",
        dest="version",
        help="report version information to stdout.",
    )
    parser.add_argument(
        "-h", "--help", action="store_true", dest="help", help="show help about options"
    )
    parser.add_argument(
        "--help-ini", "--hi", action="store_true", dest="helpini", help="show help about ini-names"
    )
    parser.add_argument(
        "-v",
        action="count",
        dest="verbose_level",
        default=0,
        help="increase verbosity of reporting output. -vv mode turns off "
        "output redirection for package installation",
    )
    parser.add_argument(
        "-q",
        action="count",
        dest="quiet_level",
        default=0,
        help="progressively silence reporting output.",
    )
    parser.add_argument(
        "--showconfig",
        action="store_true",
        help="show configuration information for all environments. ",
    )
    parser.add_argument(
        "-l",
        "--listenvs",
        action="store_true",
        dest="listenvs",
        help="show list of test environments (with description if verbose)",
    )
    parser.add_argument(
        "-a",
        "--listenvs-all",
        action="store_true",
        dest="listenvs_all",
        help="show list of all defined environments (with description if verbose)",
    )
    parser.add_argument(
        "-c",
        action="store",
        default="tox.ini",
        dest="configfile",
        help="config file name or directory with 'tox.ini' file.",
    )
    parser.add_argument(
        "-e",
        action="append",
        dest="env",
        metavar="envlist",
        help="work against specified environments (ALL selects all).",
    )
    parser.add_argument(
        "--notest", action="store_true", dest="notest", help="skip invoking test commands."
    )
    parser.add_argument(
        "--sdistonly",
        action="store_true",
        dest="sdistonly",
        help="only perform the sdist packaging activity.",
    )
    parser.add_argument(
        "--installpkg",
        action="store",
        default=None,
        metavar="PATH",
        help="use specified package for installation into venv, instead of creating an sdist.",
    )
    parser.add_argument(
        "--develop",
        action="store_true",
        dest="develop",
        help="install package in the venv using 'setup.py develop' via 'pip -e .'",
    )
    parser.add_argument(
        "-i",
        "--index-url",
        action="append",
        dest="indexurl",
        metavar="URL",
        help="set indexserver url (if URL is of form name=url set the "
        "url for the 'name' indexserver, specifically)",
    )
    parser.add_argument(
        "--pre",
        action="store_true",
        dest="pre",
        help="install pre-releases and development versions of dependencies. "
        "This will pass the --pre option to install_command "
        "(pip by default).",
    )
    parser.add_argument(
        "-r",
        "--recreate",
        action="store_true",
        dest="recreate",
        help="force recreation of virtual environments",
    )
    parser.add_argument(
        "--result-json",
        action="store",
        dest="resultjson",
        metavar="PATH",
        help="write a json file with detailed information "
        "about all commands and results involved.",
    )

    # We choose 1 to 4294967295 because it is the range of PYTHONHASHSEED.
    parser.add_argument(
        "--hashseed",
        action="store",
        metavar="SEED",
        default=None,
        help="set PYTHONHASHSEED to SEED before running commands.  "
        "Defaults to a random integer in the range [1, 4294967295] "
        "([1, 1024] on Windows). "
        "Passing 'noset' suppresses this behavior.",
    )
    parser.add_argument(
        "--force-dep",
        action="append",
        metavar="REQ",
        default=None,
        help="Forces a certain version of one of the dependencies "
        "when configuring the virtual environment. REQ Examples "
        "'pytest<2.7' or 'django>=1.6'.",
    )
    parser.add_argument(
        "--sitepackages",
        action="store_true",
        help="override sitepackages setting to True in all envs",
    )
    parser.add_argument(
        "--alwayscopy", action="store_true", help="override alwayscopy setting to True in all envs"
    )
    parser.add_argument(
        "--skip-missing-interpreters",
        action="store_true",
        help="don't fail tests for missing interpreters",
    )
    parser.add_argument(
        "--workdir",
        action="store",
        dest="workdir",
        metavar="PATH",
        default=None,
        help="tox working directory",
    )

    parser.add_argument(
        "args", nargs="*", help="additional arguments available to command positional substitution"
    )

    parser.add_testenv_attribute(
        name="envdir",
        type="path",
        default="{toxworkdir}/{envname}",
        help="set venv directory -- be very careful when changing this as tox "
        "will remove this directory when recreating an environment",
    )

    # add various core venv interpreter attributes
    def setenv(testenv_config, value):
        setenv = value
        config = testenv_config.config
        if "PYTHONHASHSEED" not in setenv and config.hashseed is not None:
            setenv["PYTHONHASHSEED"] = config.hashseed
        return setenv

    parser.add_testenv_attribute(
        name="setenv",
        type="dict_setenv",
        postprocess=setenv,
        help="list of X=Y lines with environment variable settings",
    )

    def basepython_default(testenv_config, value):
        """Configure a sane interpreter for the environment.

        If the environment contains a default factor, this will always be the
        interpreter associated with that factor overriding anything manually
        set.
        """
        for factor in testenv_config.factors:
            if factor in tox.PYTHON.DEFAULT_FACTORS:
                default = tox.PYTHON.DEFAULT_FACTORS[factor]

                if value is None or testenv_config.config.ignore_basepython_conflict:
                    return default

                if str(value) != default:
                    # TODO(stephenfin): Raise an exception here in tox 4.0
                    warnings.warn(
                        "Conflicting basepython for environment '{}'; resolve conflict "
                        "or configure ignore_basepython_conflict".format(
                            testenv_config.envname, str(value), default
                        )
                    )

        if value is None:
            return sys.executable

        return str(value)

    parser.add_testenv_attribute(
        name="basepython",
        type="string",
        default=None,
        postprocess=basepython_default,
        help="executable name or path of interpreter used to create a virtual test environment.",
    )

    def merge_description(testenv_config, value):
        """the reader by default joins generated description with new line,
         replace new line with space"""
        return value.replace("\n", " ")

    parser.add_testenv_attribute(
        name="description",
        type="string",
        default="",
        postprocess=merge_description,
        help="short description of this environment",
    )

    parser.add_testenv_attribute(
        name="envtmpdir", type="path", default="{envdir}/tmp", help="venv temporary directory"
    )

    parser.add_testenv_attribute(
        name="envlogdir", type="path", default="{envdir}/log", help="venv log directory"
    )

    parser.add_testenv_attribute(
        name="downloadcache",
        type="string",
        default=None,
        help="(ignored) has no effect anymore, pip-8 uses local caching by default",
    )

    parser.add_testenv_attribute(
        name="changedir",
        type="path",
        default="{toxinidir}",
        help="directory to change to when running commands",
    )

    parser.add_testenv_attribute_obj(PosargsOption())

    parser.add_testenv_attribute(
        name="skip_install",
        type="bool",
        default=False,
        help="Do not install the current package. This can be used when you need the virtualenv "
        "management but do not want to install the current package",
    )

    parser.add_testenv_attribute(
        name="ignore_errors",
        type="bool",
        default=False,
        help="if set to True all commands will be executed irrespective of their result error "
        "status.",
    )

    def recreate(testenv_config, value):
        if testenv_config.config.option.recreate:
            return True
        return value

    parser.add_testenv_attribute(
        name="recreate",
        type="bool",
        default=False,
        postprocess=recreate,
        help="always recreate this test environment.",
    )

    def passenv(testenv_config, value):
        # Flatten the list to deal with space-separated values.
        value = list(itertools.chain.from_iterable([x.split(" ") for x in value]))

        passenv = {"PATH", "PIP_INDEX_URL", "LANG", "LANGUAGE", "LD_LIBRARY_PATH"}

        # read in global passenv settings
        p = os.environ.get("TOX_TESTENV_PASSENV", None)
        if p is not None:
            env_values = [x for x in p.split() if x]
            value.extend(env_values)

        # we ensure that tmp directory settings are passed on
        # we could also set it to the per-venv "envtmpdir"
        # but this leads to very long paths when run with jenkins
        # so we just pass it on by default for now.
        if tox.INFO.IS_WIN:
            passenv.add("SYSTEMDRIVE")  # needed for pip6
            passenv.add("SYSTEMROOT")  # needed for python's crypto module
            passenv.add("PATHEXT")  # needed for discovering executables
            passenv.add("COMSPEC")  # needed for distutils cygwincompiler
            passenv.add("TEMP")
            passenv.add("TMP")
            # for `multiprocessing.cpu_count()` on Windows (prior to Python 3.4).
            passenv.add("NUMBER_OF_PROCESSORS")
            passenv.add("PROCESSOR_ARCHITECTURE")  # platform.machine()
            passenv.add("USERPROFILE")  # needed for `os.path.expanduser()`
            passenv.add("MSYSTEM")  # fixes #429
        else:
            passenv.add("TMPDIR")
        for spec in value:
            for name in os.environ:
                if fnmatchcase(name.upper(), spec.upper()):
                    passenv.add(name)
        return passenv

    parser.add_testenv_attribute(
        name="passenv",
        type="line-list",
        postprocess=passenv,
        help="environment variables needed during executing test commands (taken from invocation "
        "environment). Note that tox always  passes through some basic environment variables "
        "which are needed for basic functioning of the Python system. See --showconfig for the "
        "eventual passenv setting.",
    )

    parser.add_testenv_attribute(
        name="whitelist_externals",
        type="line-list",
        help="each lines specifies a path or basename for which tox will not warn "
        "about it coming from outside the test environment.",
    )

    parser.add_testenv_attribute(
        name="platform",
        type="string",
        default=".*",
        help="regular expression which must match against ``sys.platform``. "
        "otherwise testenv will be skipped.",
    )

    def sitepackages(testenv_config, value):
        return testenv_config.config.option.sitepackages or value

    def alwayscopy(testenv_config, value):
        return testenv_config.config.option.alwayscopy or value

    parser.add_testenv_attribute(
        name="sitepackages",
        type="bool",
        default=False,
        postprocess=sitepackages,
        help="Set to ``True`` if you want to create virtual environments that also "
        "have access to globally installed packages.",
    )

    parser.add_testenv_attribute(
        name="alwayscopy",
        type="bool",
        default=False,
        postprocess=alwayscopy,
        help="Set to ``True`` if you want virtualenv to always copy files rather "
        "than symlinking.",
    )

    def pip_pre(testenv_config, value):
        return testenv_config.config.option.pre or value

    parser.add_testenv_attribute(
        name="pip_pre",
        type="bool",
        default=False,
        postprocess=pip_pre,
        help="If ``True``, adds ``--pre`` to the ``opts`` passed to the install command. ",
    )

    def develop(testenv_config, value):
        option = testenv_config.config.option
        return not option.installpkg and (value or option.develop)

    parser.add_testenv_attribute(
        name="usedevelop",
        type="bool",
        postprocess=develop,
        default=False,
        help="install package in develop/editable mode",
    )

    parser.add_testenv_attribute_obj(InstallcmdOption())

    parser.add_testenv_attribute(
        name="list_dependencies_command",
        type="argv",
        default="pip freeze",
        help="list dependencies for a virtual environment",
    )

    parser.add_testenv_attribute_obj(DepOption())

    parser.add_testenv_attribute(
        name="commands",
        type="argvlist",
        default="",
        help="each line specifies a test command and can use substitution.",
    )

    parser.add_testenv_attribute(
        "ignore_outcome",
        type="bool",
        default=False,
        help="if set to True a failing result of this testenv will not make "
        "tox fail, only a warning will be produced",
    )

    parser.add_testenv_attribute(
        "extras",
        type="line-list",
        help="list of extras to install with the source distribution or develop install",
    )


class Config(object):
    """Global Tox config object."""

    def __init__(self, pluginmanager, option, interpreters):
        self.envconfigs = {}
        """Mapping envname -> envconfig"""
        self.invocationcwd = py.path.local()
        self.interpreters = interpreters
        self.pluginmanager = pluginmanager
        self.option = option
        """option namespace containing all parsed command line options"""

    @property
    def homedir(self):
        homedir = get_homedir()
        if homedir is None:
            homedir = self.toxinidir  # FIXME XXX good idea?
        return homedir


class TestenvConfig:
    """Testenv Configuration object.

    In addition to some core attributes/properties this config object holds all
    per-testenv ini attributes as attributes, see "tox --help-ini" for an overview.
    """

    def __init__(self, envname, config, factors, reader):
        #: test environment name
        self.envname = envname
        #: global tox config object
        self.config = config
        #: set of factors
        self.factors = factors
        self._reader = reader
        self.missing_subs = []
        """Holds substitutions that could not be resolved.

        Pre 2.8.1 missing substitutions crashed with a ConfigError although this would not be a
        problem if the env is not part of the current testrun. So we need to remember this and
        check later when the testenv is actually run and crash only then.
        """

    def get_envbindir(self):
        """Path to directory where scripts/binaries reside."""
        if tox.INFO.IS_WIN and "jython" not in self.basepython and "pypy" not in self.basepython:
            return self.envdir.join("Scripts")
        else:
            return self.envdir.join("bin")

    @property
    def envbindir(self):
        return self.get_envbindir()

    @property
    def envpython(self):
        """Path to python executable."""
        return self.get_envpython()

    def get_envpython(self):
        """ path to python/jython executable. """
        if "jython" in str(self.basepython):
            name = "jython"
        else:
            name = "python"
        return self.envbindir.join(name)

    def get_envsitepackagesdir(self):
        """Return sitepackagesdir of the virtualenv environment.

        NOTE: Only available during execution, not during parsing.
        """
        x = self.config.interpreters.get_sitepackagesdir(info=self.python_info, envdir=self.envdir)
        return x

    @property
    def python_info(self):
        """Return sitepackagesdir of the virtualenv environment."""
        return self.config.interpreters.get_info(envconfig=self)

    def getsupportedinterpreter(self):
        if tox.INFO.IS_WIN and self.basepython and "jython" in self.basepython:
            raise tox.exception.UnsupportedInterpreter(
                "Jython/Windows does not support installing scripts"
            )
        info = self.config.interpreters.get_info(envconfig=self)
        if not info.executable:
            raise tox.exception.InterpreterNotFound(self.basepython)
        if not info.version_info:
            raise tox.exception.InvocationError(
                "Failed to get version_info for {}: {}".format(info.name, info.err)
            )
        return info.executable


testenvprefix = "testenv:"


def get_homedir():
    try:
        return py.path.local._gethomedir()
    except Exception:
        return None


def make_hashseed():
    max_seed = 4294967295
    if tox.INFO.IS_WIN:
        max_seed = 1024
    return str(random.randint(1, max_seed))


class parseini:
    def __init__(self, config, inipath):
        config.toxinipath = inipath
        config.toxinidir = config.toxinipath.dirpath()

        self._cfg = py.iniconfig.IniConfig(config.toxinipath)
        config._cfg = self._cfg
        self.config = config

        if inipath.basename == "setup.cfg":
            prefix = "tox"
        else:
            prefix = None
        ctxname = getcontextname()
        if ctxname == "jenkins":
            reader = SectionReader(
                "tox:jenkins", self._cfg, prefix=prefix, fallbacksections=["tox"]
            )
            distshare_default = "{toxworkdir}/distshare"
        elif not ctxname:
            reader = SectionReader("tox", self._cfg, prefix=prefix)
            distshare_default = "{homedir}/.tox/distshare"
        else:
            raise ValueError("invalid context")

        if config.option.hashseed is None:
            hashseed = make_hashseed()
        elif config.option.hashseed == "noset":
            hashseed = None
        else:
            hashseed = config.option.hashseed
        config.hashseed = hashseed

        reader.addsubstitutions(toxinidir=config.toxinidir, homedir=config.homedir)
        # As older versions of tox may have bugs or incompatibilities that
        # prevent parsing of tox.ini this must be the first thing checked.
        config.minversion = reader.getstring("minversion", None)
        if config.minversion:
            tox_version = parse(tox.__version__)
            config_min_version = parse(self.config.minversion)
            if config_min_version > tox_version:
                raise tox.exception.MinVersionError(
                    "tox version is {}, required is at least {}".format(
                        tox.__version__, self.config.minversion
                    )
                )
        if config.option.workdir is None:
            config.toxworkdir = reader.getpath("toxworkdir", "{toxinidir}/.tox")
        else:
            config.toxworkdir = config.toxinidir.join(config.option.workdir, abs=True)

        if not config.option.skip_missing_interpreters:
            config.option.skip_missing_interpreters = reader.getbool(
                "skip_missing_interpreters", False
            )

        config.ignore_basepython_conflict = reader.getbool("ignore_basepython_conflict", False)

        # determine indexserver dictionary
        config.indexserver = {"default": IndexServerConfig("default")}
        prefix = "indexserver"
        for line in reader.getlist(prefix):
            name, url = map(lambda x: x.strip(), line.split("=", 1))
            config.indexserver[name] = IndexServerConfig(name, url)

        override = False
        if config.option.indexurl:
            for urldef in config.option.indexurl:
                m = re.match(r"\W*(\w+)=(\S+)", urldef)
                if m is None:
                    url = urldef
                    name = "default"
                else:
                    name, url = m.groups()
                    if not url:
                        url = None
                if name != "ALL":
                    config.indexserver[name].url = url
                else:
                    override = url
        # let ALL override all existing entries
        if override:
            for name in config.indexserver:
                config.indexserver[name] = IndexServerConfig(name, override)

        config.build = reader.getstring("build", default="sdist")
        reader.addsubstitutions(toxworkdir=config.toxworkdir)
        config.distdir = reader.getpath("distdir", "{toxworkdir}/dist")
        reader.addsubstitutions(distdir=config.distdir)
        config.distshare = reader.getpath("distshare", distshare_default)
        reader.addsubstitutions(distshare=config.distshare)
        config.sdistsrc = reader.getpath("sdistsrc", None)
        config.setupdir = reader.getpath("setupdir", "{toxinidir}")
        config.logdir = config.toxworkdir.join("log")

        config.envlist, all_envs = self._getenvdata(reader)

        # factors used in config or predefined
        known_factors = self._list_section_factors("testenv")
        known_factors.update(tox.PYTHON.DEFAULT_FACTORS)
        known_factors.add("python")

        # factors stated in config envlist
        stated_envlist = reader.getstring("envlist", replace=False)
        if stated_envlist:
            for env in _split_env(stated_envlist):
                known_factors.update(env.split("-"))

        # configure testenvs
        for name in all_envs:
            section = testenvprefix + name
            factors = set(name.split("-"))
            if section in self._cfg or factors <= known_factors:
                config.envconfigs[name] = self.make_envconfig(name, section, reader._subs, config)

        all_develop = all(
            name in config.envconfigs and config.envconfigs[name].usedevelop
            for name in config.envlist
        )

        config.skipsdist = reader.getbool("skipsdist", all_develop)

    def _list_section_factors(self, section):
        factors = set()
        if section in self._cfg:
            for _, value in self._cfg[section].items():
                exprs = re.findall(r"^([\w{}\.!,-]+)\:\s+", value, re.M)
                factors.update(*mapcat(_split_factor_expr_all, exprs))
        return factors

    def make_envconfig(self, name, section, subs, config, replace=True):
        factors = set(name.split("-"))
        reader = SectionReader(section, self._cfg, fallbacksections=["testenv"], factors=factors)
        tc = TestenvConfig(name, config, factors, reader)
        reader.addsubstitutions(
            envname=name,
            envbindir=tc.get_envbindir,
            envsitepackagesdir=tc.get_envsitepackagesdir,
            envpython=tc.get_envpython,
            **subs
        )
        for env_attr in config._testenv_attr:
            atype = env_attr.type
            try:
                if atype in ("bool", "path", "string", "dict", "dict_setenv", "argv", "argvlist"):
                    meth = getattr(reader, "get" + atype)
                    res = meth(env_attr.name, env_attr.default, replace=replace)
                elif atype == "space-separated-list":
                    res = reader.getlist(env_attr.name, sep=" ")
                elif atype == "line-list":
                    res = reader.getlist(env_attr.name, sep="\n")
                else:
                    raise ValueError("unknown type {!r}".format(atype))
                if env_attr.postprocess:
                    res = env_attr.postprocess(testenv_config=tc, value=res)
            except tox.exception.MissingSubstitution as e:
                tc.missing_subs.append(e.name)
                res = e.FLAG
            setattr(tc, env_attr.name, res)
            if atype in ("path", "string"):
                reader.addsubstitutions(**{env_attr.name: res})
        return tc

    def _getenvdata(self, reader):
        candidates = (
            self.config.option.env,
            os.environ.get("TOXENV"),
            reader.getstring("envlist", replace=False),
        )
        env_str = next((i for i in candidates if i), [])
        env_list = _split_env(env_str)

        # collect section envs
        all_envs = set(env_list) - {"ALL"}
        for section in self._cfg:
            if section.name.startswith(testenvprefix):
                all_envs.add(section.name[len(testenvprefix) :])
        if not all_envs:
            all_envs.add("python")

        if not env_list or "ALL" in env_list:
            env_list = sorted(all_envs)

        return env_list, all_envs


def _split_env(env):
    """if handed a list, action="append" was used for -e """
    if not isinstance(env, list):
        env = [e.split("#", 1)[0].strip() for e in env.split("\n")]
        env = ",".join([e for e in env if e])
        env = [env]
    return mapcat(_expand_envstr, env)


def _is_negated_factor(factor):
    return factor.startswith("!")


def _base_factor_name(factor):
    return factor[1:] if _is_negated_factor(factor) else factor


def _split_factor_expr(expr):
    def split_single(e):
        raw = e.split("-")
        included = {_base_factor_name(factor) for factor in raw if not _is_negated_factor(factor)}
        excluded = {_base_factor_name(factor) for factor in raw if _is_negated_factor(factor)}
        return included, excluded

    partial_envs = _expand_envstr(expr)
    return [split_single(e) for e in partial_envs]


def _split_factor_expr_all(expr):
    partial_envs = _expand_envstr(expr)
    return [{_base_factor_name(factor) for factor in e.split("-")} for e in partial_envs]


def _expand_envstr(envstr):
    # split by commas not in groups
    tokens = re.split(r"((?:\{[^}]+\})+)|,", envstr)
    envlist = ["".join(g).strip() for k, g in itertools.groupby(tokens, key=bool) if k]

    def expand(env):
        tokens = re.split(r"\{([^}]+)\}", env)
        parts = [re.sub(r"\s+", "", token).split(",") for token in tokens]
        return ["".join(variant) for variant in itertools.product(*parts)]

    return mapcat(expand, envlist)


def mapcat(f, seq):
    return list(itertools.chain.from_iterable(map(f, seq)))


class DepConfig:
    def __init__(self, name, indexserver=None):
        self.name = name
        self.indexserver = indexserver

    def __str__(self):
        if self.indexserver:
            if self.indexserver.name == "default":
                return self.name
            return ":{}:{}".format(self.indexserver.name, self.name)
        return str(self.name)

    __repr__ = __str__


class IndexServerConfig:
    def __init__(self, name, url=None):
        self.name = name
        self.url = url


is_section_substitution = re.compile(r"{\[[^{}\s]+\]\S+?}").match
"""Check value matches substitution form of referencing value from other section.

E.g. {[base]commands}
"""


class SectionReader:
    def __init__(self, section_name, cfgparser, fallbacksections=None, factors=(), prefix=None):
        if prefix is None:
            self.section_name = section_name
        else:
            self.section_name = "{}:{}".format(prefix, section_name)
        self._cfg = cfgparser
        self.fallbacksections = fallbacksections or []
        self.factors = factors
        self._subs = {}
        self._subststack = []
        self._setenv = None

    def get_environ_value(self, name):
        if self._setenv is None:
            return os.environ.get(name)
        return self._setenv.get(name)

    def addsubstitutions(self, _posargs=None, **kw):
        self._subs.update(kw)
        if _posargs:
            self.posargs = _posargs

    def getpath(self, name, defaultpath, replace=True):
        path = self.getstring(name, defaultpath, replace=replace)
        if path is not None:
            toxinidir = self._subs["toxinidir"]
            return toxinidir.join(path, abs=True)

    def getlist(self, name, sep="\n"):
        s = self.getstring(name, None)
        if s is None:
            return []
        return [x.strip() for x in s.split(sep) if x.strip()]

    def getdict(self, name, default=None, sep="\n", replace=True):
        value = self.getstring(name, None, replace=replace)
        return self._getdict(value, default=default, sep=sep, replace=replace)

    def getdict_setenv(self, name, default=None, sep="\n", replace=True):
        value = self.getstring(name, None, replace=replace, crossonly=True)
        definitions = self._getdict(value, default=default, sep=sep, replace=replace)
        self._setenv = SetenvDict(definitions, reader=self)
        return self._setenv

    def _getdict(self, value, default, sep, replace=True):
        if value is None or not replace:
            return default or {}

        d = {}
        for line in value.split(sep):
            if line.strip():
                name, rest = line.split("=", 1)
                d[name.strip()] = rest.strip()

        return d

    def getbool(self, name, default=None, replace=True):
        s = self.getstring(name, default, replace=replace)
        if not s or not replace:
            s = default
        if s is None:
            raise KeyError("no config value [{}] {} found".format(self.section_name, name))

        if not isinstance(s, bool):
            if s.lower() == "true":
                s = True
            elif s.lower() == "false":
                s = False
            else:
                raise tox.exception.ConfigError("boolean value %r needs to be 'True' or 'False'")
        return s

    def getargvlist(self, name, default="", replace=True):
        s = self.getstring(name, default, replace=False)
        return _ArgvlistReader.getargvlist(self, s, replace=replace)

    def getargv(self, name, default="", replace=True):
        return self.getargvlist(name, default, replace=replace)[0]

    def getstring(self, name, default=None, replace=True, crossonly=False):
        x = None
        for s in [self.section_name] + self.fallbacksections:
            try:
                x = self._cfg[s][name]
                break
            except KeyError:
                continue

        if x is None:
            x = default
        else:
            x = self._replace_if_needed(x, name, replace, crossonly)
            x = self._apply_factors(x)

        x = self._replace_if_needed(x, name, replace, crossonly)
        # print "getstring", self.section_name, name, "returned", repr(x)
        return x

    def _apply_factors(self, s):
        def factor_line(line):
            m = re.search(r"^([\w{}\.!,-]+)\:\s+(.+)", line)
            if not m:
                return line

            expr, line = m.groups()
            if any(
                included <= self.factors and not any(x in self.factors for x in excluded)
                for included, excluded in _split_factor_expr(expr)
            ):
                return line

        lines = s.strip().splitlines()
        return "\n".join(filter(None, map(factor_line, lines)))

    def _replace(self, value, name=None, section_name=None, crossonly=False):
        if "{" not in value:
            return value

        section_name = section_name if section_name else self.section_name
        self._subststack.append((section_name, name))
        try:
            replaced = Replacer(self, crossonly=crossonly).do_replace(value)
            assert self._subststack.pop() == (section_name, name)
        except tox.exception.MissingSubstitution:
            if not section_name.startswith(testenvprefix):
                raise tox.exception.ConfigError(
                    "substitution env:{!r}: unknown or recursive definition in"
                    " section {!r}.".format(value, section_name)
                )
            raise
        return replaced

    def _replace_if_needed(self, x, name, replace, crossonly):
        if replace and x and hasattr(x, "replace"):
            x = self._replace(x, name=name, crossonly=crossonly)
        return x


class Replacer:
    RE_ITEM_REF = re.compile(
        r"""
        (?<!\\)[{]
        (?:(?P<sub_type>[^[:{}]+):)?    # optional sub_type for special rules
        (?P<substitution_value>(?:\[[^,{}]*\])?[^:,{}]*)  # substitution key
        (?::(?P<default_value>[^{}]*))?   # default value
        [}]
        """,
        re.VERBOSE,
    )

    def __init__(self, reader, crossonly=False):
        self.reader = reader
        self.crossonly = crossonly

    def do_replace(self, value):
        """
        Recursively expand substitutions starting from the innermost expression
        """

        def substitute_once(x):
            return self.RE_ITEM_REF.sub(self._replace_match, x)

        expanded = substitute_once(value)

        while expanded != value:  # substitution found
            value = expanded
            expanded = substitute_once(value)

        return expanded

    def _replace_match(self, match):
        g = match.groupdict()
        sub_value = g["substitution_value"]
        if self.crossonly:
            if sub_value.startswith("["):
                return self._substitute_from_other_section(sub_value)
            # in crossonly we return all other hits verbatim
            start, end = match.span()
            return match.string[start:end]

        # special case: all empty values means ":" which is os.pathsep
        if not any(g.values()):
            return os.pathsep

        # special case: opts and packages. Leave {opts} and
        # {packages} intact, they are replaced manually in
        # _venv.VirtualEnv.run_install_command.
        if sub_value in ("opts", "packages"):
            return "{{{}}}".format(sub_value)

        try:
            sub_type = g["sub_type"]
        except KeyError:
            raise tox.exception.ConfigError(
                "Malformed substitution; no substitution type provided"
            )

        if sub_type == "env":
            return self._replace_env(match)
        if sub_type is not None:
            raise tox.exception.ConfigError(
                "No support for the {} substitution type".format(sub_type)
            )
        return self._replace_substitution(match)

    def _replace_env(self, match):
        envkey = match.group("substitution_value")
        if not envkey:
            raise tox.exception.ConfigError("env: requires an environment variable name")
        default = match.group("default_value")
        envvalue = self.reader.get_environ_value(envkey)
        if envvalue is not None:
            return envvalue
        if default is not None:
            return default
        raise tox.exception.MissingSubstitution(envkey)

    def _substitute_from_other_section(self, key):
        if key.startswith("[") and "]" in key:
            i = key.find("]")
            section, item = key[1:i], key[i + 1 :]
            cfg = self.reader._cfg
            if section in cfg and item in cfg[section]:
                if (section, item) in self.reader._subststack:
                    raise ValueError(
                        "{} already in {}".format((section, item), self.reader._subststack)
                    )
                x = str(cfg[section][item])
                return self.reader._replace(
                    x, name=item, section_name=section, crossonly=self.crossonly
                )

        raise tox.exception.ConfigError("substitution key {!r} not found".format(key))

    def _replace_substitution(self, match):
        sub_key = match.group("substitution_value")
        val = self.reader._subs.get(sub_key, None)
        if val is None:
            val = self._substitute_from_other_section(sub_key)
        if callable(val):
            val = val()
        return str(val)


class _ArgvlistReader:
    @classmethod
    def getargvlist(cls, reader, value, replace=True):
        """Parse ``commands`` argvlist multiline string.

        :param SectionReader reader: reader to be used.
        :param str value: Content stored by key.

        :rtype: list[list[str]]
        :raise :class:`tox.exception.ConfigError`:
            line-continuation ends nowhere while resolving for specified section
        """
        commands = []
        current_command = ""
        for line in value.splitlines():
            line = line.rstrip()
            if not line:
                continue
            if line.endswith("\\"):
                current_command += " " + line[:-1]
                continue
            current_command += line

            if is_section_substitution(current_command):
                replaced = reader._replace(current_command, crossonly=True)
                commands.extend(cls.getargvlist(reader, replaced))
            else:
                commands.append(cls.processcommand(reader, current_command, replace))
            current_command = ""
        else:
            if current_command:
                raise tox.exception.ConfigError(
                    "line-continuation ends nowhere while resolving for [{}] {}".format(
                        reader.section_name, "commands"
                    )
                )
        return commands

    @classmethod
    def processcommand(cls, reader, command, replace=True):
        posargs = getattr(reader, "posargs", "")
        posargs_string = list2cmdline([x for x in posargs if x])

        # Iterate through each word of the command substituting as
        # appropriate to construct the new command string. This
        # string is then broken up into exec argv components using
        # shlex.
        if replace:
            newcommand = ""
            for word in CommandParser(command).words():
                if word == "{posargs}" or word == "[]":
                    newcommand += posargs_string
                    continue
                elif word.startswith("{posargs:") and word.endswith("}"):
                    if posargs:
                        newcommand += posargs_string
                        continue
                    else:
                        word = word[9:-1]
                new_arg = ""
                new_word = reader._replace(word)
                new_word = reader._replace(new_word)
                new_word = new_word.replace("\\{", "{").replace("\\}", "}")
                new_arg += new_word
                newcommand += new_arg
        else:
            newcommand = command

        # Construct shlex object that will not escape any values,
        # use all values as is in argv.
        shlexer = shlex.shlex(newcommand, posix=True)
        shlexer.whitespace_split = True
        shlexer.escape = ""
        return list(shlexer)


class CommandParser(object):
    class State(object):
        def __init__(self):
            self.word = ""
            self.depth = 0
            self.yield_words = []

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

    def words(self):
        ps = CommandParser.State()

        def word_has_ended():
            return (
                (
                    cur_char in string.whitespace
                    and ps.word
                    and ps.word[-1] not in string.whitespace
                )
                or (cur_char == "{" and ps.depth == 0 and not ps.word.endswith("\\"))
                or (ps.depth == 0 and ps.word and ps.word[-1] == "}")
                or (cur_char not in string.whitespace and ps.word and ps.word.strip() == "")
            )

        def yield_this_word():
            yieldword = ps.word
            ps.word = ""
            if yieldword:
                ps.yield_words.append(yieldword)

        def yield_if_word_ended():
            if word_has_ended():
                yield_this_word()

        def accumulate():
            ps.word += cur_char

        def push_substitution():
            ps.depth += 1

        def pop_substitution():
            ps.depth -= 1

        for cur_char in self.command:
            if cur_char in string.whitespace:
                if ps.depth == 0:
                    yield_if_word_ended()
                accumulate()
            elif cur_char == "{":
                yield_if_word_ended()
                accumulate()
                push_substitution()
            elif cur_char == "}":
                accumulate()
                pop_substitution()
            else:
                yield_if_word_ended()
                accumulate()

        if ps.word.strip():
            yield_this_word()
        return ps.yield_words


def getcontextname():
    if any(env in os.environ for env in ["JENKINS_URL", "HUDSON_URL"]):
        return "jenkins"
    return None