python.py

""" Python test discovery, setup and run of test functions. """
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import collections
import fnmatch
import inspect
import os
import sys
import warnings
from functools import partial
from textwrap import dedent

import py
import six

import _pytest
from _pytest import deprecated
from _pytest import fixtures
from _pytest import nodes
from _pytest._code import filter_traceback
from _pytest.compat import ascii_escaped
from _pytest.compat import enum
from _pytest.compat import get_default_arg_names
from _pytest.compat import get_real_func
from _pytest.compat import getfslineno
from _pytest.compat import getimfunc
from _pytest.compat import getlocation
from _pytest.compat import is_generator
from _pytest.compat import isclass
from _pytest.compat import isfunction
from _pytest.compat import NoneType
from _pytest.compat import NOTSET
from _pytest.compat import REGEX_TYPE
from _pytest.compat import safe_getattr
from _pytest.compat import safe_isclass
from _pytest.compat import safe_str
from _pytest.compat import STRING_TYPES
from _pytest.config import hookimpl
from _pytest.main import FSHookProxy
from _pytest.mark import MARK_GEN
from _pytest.mark.structures import get_unpacked_marks
from _pytest.mark.structures import normalize_mark_list
from _pytest.outcomes import fail
from _pytest.pathlib import parts
from _pytest.warning_types import PytestWarning


def pyobj_property(name):
    def get(self):
        node = self.getparent(getattr(__import__("pytest"), name))
        if node is not None:
            return node.obj

    doc = "python %s object this node was collected from (can be None)." % (
        name.lower(),
    )
    return property(get, None, None, doc)


def pytest_addoption(parser):
    group = parser.getgroup("general")
    group.addoption(
        "--fixtures",
        "--funcargs",
        action="store_true",
        dest="showfixtures",
        default=False,
        help="show available fixtures, sorted by plugin appearance "
        "(fixtures with leading '_' are only shown with '-v')",
    )
    group.addoption(
        "--fixtures-per-test",
        action="store_true",
        dest="show_fixtures_per_test",
        default=False,
        help="show fixtures per test",
    )
    parser.addini(
        "usefixtures",
        type="args",
        default=[],
        help="list of default fixtures to be used with this project",
    )
    parser.addini(
        "python_files",
        type="args",
        default=["test_*.py", "*_test.py"],
        help="glob-style file patterns for Python test module discovery",
    )
    parser.addini(
        "python_classes",
        type="args",
        default=["Test"],
        help="prefixes or glob names for Python test class discovery",
    )
    parser.addini(
        "python_functions",
        type="args",
        default=["test"],
        help="prefixes or glob names for Python test function and method discovery",
    )

    group.addoption(
        "--import-mode",
        default="prepend",
        choices=["prepend", "append"],
        dest="importmode",
        help="prepend/append to sys.path when importing test modules, "
        "default is to prepend.",
    )


def pytest_cmdline_main(config):
    if config.option.showfixtures:
        showfixtures(config)
        return 0
    if config.option.show_fixtures_per_test:
        show_fixtures_per_test(config)
        return 0


def pytest_generate_tests(metafunc):
    # those alternative spellings are common - raise a specific error to alert
    # the user
    alt_spellings = ["parameterize", "parametrise", "parameterise"]
    for mark_name in alt_spellings:
        if metafunc.definition.get_closest_marker(mark_name):
            msg = "{0} has '{1}' mark, spelling should be 'parametrize'"
            fail(msg.format(metafunc.function.__name__, mark_name), pytrace=False)
    for marker in metafunc.definition.iter_markers(name="parametrize"):
        metafunc.parametrize(*marker.args, **marker.kwargs)


def pytest_configure(config):
    config.addinivalue_line(
        "markers",
        "parametrize(argnames, argvalues): call a test function multiple "
        "times passing in different arguments in turn. argvalues generally "
        "needs to be a list of values if argnames specifies only one name "
        "or a list of tuples of values if argnames specifies multiple names. "
        "Example: @parametrize('arg1', [1,2]) would lead to two calls of the "
        "decorated test function, one with arg1=1 and another with arg1=2."
        "see https://docs.pytest.org/en/latest/parametrize.html for more info "
        "and examples.",
    )
    config.addinivalue_line(
        "markers",
        "usefixtures(fixturename1, fixturename2, ...): mark tests as needing "
        "all of the specified fixtures. see "
        "https://docs.pytest.org/en/latest/fixture.html#usefixtures ",
    )


@hookimpl(trylast=True)
def pytest_pyfunc_call(pyfuncitem):
    testfunction = pyfuncitem.obj
    funcargs = pyfuncitem.funcargs
    testargs = {arg: funcargs[arg] for arg in pyfuncitem._fixtureinfo.argnames}
    testfunction(**testargs)
    return True


def pytest_collect_file(path, parent):
    ext = path.ext
    if ext == ".py":
        if not parent.session.isinitpath(path):
            if not path_matches_patterns(
                path, parent.config.getini("python_files") + ["__init__.py"]
            ):
                return
        ihook = parent.session.gethookproxy(path)
        return ihook.pytest_pycollect_makemodule(path=path, parent=parent)


def path_matches_patterns(path, patterns):
    """Returns True if the given py.path.local matches one of the patterns in the list of globs given"""
    return any(path.fnmatch(pattern) for pattern in patterns)


def pytest_pycollect_makemodule(path, parent):
    if path.basename == "__init__.py":
        return Package(path, parent)
    return Module(path, parent)


@hookimpl(hookwrapper=True)
def pytest_pycollect_makeitem(collector, name, obj):
    outcome = yield
    res = outcome.get_result()
    if res is not None:
        return
    # nothing was collected elsewhere, let's do it here
    if safe_isclass(obj):
        if collector.istestclass(obj, name):
            outcome.force_result(Class(name, parent=collector))
    elif collector.istestfunction(obj, name):
        # mock seems to store unbound methods (issue473), normalize it
        obj = getattr(obj, "__func__", obj)
        # We need to try and unwrap the function if it's a functools.partial
        # or a funtools.wrapped.
        # We musn't if it's been wrapped with mock.patch (python 2 only)
        if not (isfunction(obj) or isfunction(get_real_func(obj))):
            filename, lineno = getfslineno(obj)
            warnings.warn_explicit(
                message=PytestWarning(
                    "cannot collect %r because it is not a function." % name
                ),
                category=None,
                filename=str(filename),
                lineno=lineno + 1,
            )
        elif getattr(obj, "__test__", True):
            if is_generator(obj):
                res = Function(name, parent=collector)
                reason = deprecated.YIELD_TESTS.format(name=name)
                res.add_marker(MARK_GEN.xfail(run=False, reason=reason))
                res.warn(PytestWarning(reason))
            else:
                res = list(collector._genfunctions(name, obj))
            outcome.force_result(res)


def pytest_make_parametrize_id(config, val, argname=None):
    return None


class PyobjContext(object):
    module = pyobj_property("Module")
    cls = pyobj_property("Class")
    instance = pyobj_property("Instance")


class PyobjMixin(PyobjContext):
    _ALLOW_MARKERS = True

    def __init__(self, *k, **kw):
        super(PyobjMixin, self).__init__(*k, **kw)

    def obj():
        def fget(self):
            obj = getattr(self, "_obj", None)
            if obj is None:
                self._obj = obj = self._getobj()
                # XXX evil hack
                # used to avoid Instance collector marker duplication
                if self._ALLOW_MARKERS:
                    self.own_markers.extend(get_unpacked_marks(self.obj))
            return obj

        def fset(self, value):
            self._obj = value

        return property(fget, fset, None, "underlying python object")

    obj = obj()

    def _getobj(self):
        return getattr(self.parent.obj, self.name)

    def getmodpath(self, stopatmodule=True, includemodule=False):
        """ return python path relative to the containing module. """
        chain = self.listchain()
        chain.reverse()
        parts = []
        for node in chain:
            if isinstance(node, Instance):
                continue
            name = node.name
            if isinstance(node, Module):
                name = os.path.splitext(name)[0]
                if stopatmodule:
                    if includemodule:
                        parts.append(name)
                    break
            parts.append(name)
        parts.reverse()
        s = ".".join(parts)
        return s.replace(".[", "[")

    def reportinfo(self):
        # XXX caching?
        obj = self.obj
        compat_co_firstlineno = getattr(obj, "compat_co_firstlineno", None)
        if isinstance(compat_co_firstlineno, int):
            # nose compatibility
            fspath = sys.modules[obj.__module__].__file__
            if fspath.endswith(".pyc"):
                fspath = fspath[:-1]
            lineno = compat_co_firstlineno
        else:
            fspath, lineno = getfslineno(obj)
        modpath = self.getmodpath()
        assert isinstance(lineno, int)
        return fspath, lineno, modpath


class PyCollector(PyobjMixin, nodes.Collector):
    def funcnamefilter(self, name):
        return self._matches_prefix_or_glob_option("python_functions", name)

    def isnosetest(self, obj):
        """ Look for the __test__ attribute, which is applied by the
        @nose.tools.istest decorator
        """
        # We explicitly check for "is True" here to not mistakenly treat
        # classes with a custom __getattr__ returning something truthy (like a
        # function) as test classes.
        return safe_getattr(obj, "__test__", False) is True

    def classnamefilter(self, name):
        return self._matches_prefix_or_glob_option("python_classes", name)

    def istestfunction(self, obj, name):
        if self.funcnamefilter(name) or self.isnosetest(obj):
            if isinstance(obj, staticmethod):
                # static methods need to be unwrapped
                obj = safe_getattr(obj, "__func__", False)
            return (
                safe_getattr(obj, "__call__", False)
                and fixtures.getfixturemarker(obj) is None
            )
        else:
            return False

    def istestclass(self, obj, name):
        return self.classnamefilter(name) or self.isnosetest(obj)

    def _matches_prefix_or_glob_option(self, option_name, name):
        """
        checks if the given name matches the prefix or glob-pattern defined
        in ini configuration.
        """
        for option in self.config.getini(option_name):
            if name.startswith(option):
                return True
            # check that name looks like a glob-string before calling fnmatch
            # because this is called for every name in each collected module,
            # and fnmatch is somewhat expensive to call
            elif ("*" in option or "?" in option or "[" in option) and fnmatch.fnmatch(
                name, option
            ):
                return True
        return False

    def collect(self):
        if not getattr(self.obj, "__test__", True):
            return []

        # NB. we avoid random getattrs and peek in the __dict__ instead
        # (XXX originally introduced from a PyPy need, still true?)
        dicts = [getattr(self.obj, "__dict__", {})]
        for basecls in inspect.getmro(self.obj.__class__):
            dicts.append(basecls.__dict__)
        seen = {}
        values = []
        for dic in dicts:
            for name, obj in list(dic.items()):
                if name in seen:
                    continue
                seen[name] = True
                res = self._makeitem(name, obj)
                if res is None:
                    continue
                if not isinstance(res, list):
                    res = [res]
                values.extend(res)
        values.sort(key=lambda item: item.reportinfo()[:2])
        return values

    def _makeitem(self, name, obj):
        # assert self.ihook.fspath == self.fspath, self
        return self.ihook.pytest_pycollect_makeitem(collector=self, name=name, obj=obj)

    def _genfunctions(self, name, funcobj):
        module = self.getparent(Module).obj
        clscol = self.getparent(Class)
        cls = clscol and clscol.obj or None
        fm = self.session._fixturemanager

        definition = FunctionDefinition(name=name, parent=self, callobj=funcobj)
        fixtureinfo = fm.getfixtureinfo(definition, funcobj, cls)

        metafunc = Metafunc(
            definition, fixtureinfo, self.config, cls=cls, module=module
        )
        methods = []
        if hasattr(module, "pytest_generate_tests"):
            methods.append(module.pytest_generate_tests)
        if hasattr(cls, "pytest_generate_tests"):
            methods.append(cls().pytest_generate_tests)
        if methods:
            self.ihook.pytest_generate_tests.call_extra(
                methods, dict(metafunc=metafunc)
            )
        else:
            self.ihook.pytest_generate_tests(metafunc=metafunc)

        if not metafunc._calls:
            yield Function(name, parent=self, fixtureinfo=fixtureinfo)
        else:
            # add funcargs() as fixturedefs to fixtureinfo.arg2fixturedefs
            fixtures.add_funcarg_pseudo_fixture_def(self, metafunc, fm)

            # add_funcarg_pseudo_fixture_def may have shadowed some fixtures
            # with direct parametrization, so make sure we update what the
            # function really needs.
            fixtureinfo.prune_dependency_tree()

            for callspec in metafunc._calls:
                subname = "%s[%s]" % (name, callspec.id)
                yield Function(
                    name=subname,
                    parent=self,
                    callspec=callspec,
                    callobj=funcobj,
                    fixtureinfo=fixtureinfo,
                    keywords={callspec.id: True},
                    originalname=name,
                )


class Module(nodes.File, PyCollector):
    """ Collector for test classes and functions. """

    def _getobj(self):
        return self._importtestmodule()

    def collect(self):
        self._inject_setup_module_fixture()
        self._inject_setup_function_fixture()
        self.session._fixturemanager.parsefactories(self)
        return super(Module, self).collect()

    def _inject_setup_module_fixture(self):
        """Injects a hidden autouse, module scoped fixture into the collected module object
        that invokes setUpModule/tearDownModule if either or both are available.

        Using a fixture to invoke this methods ensures we play nicely and unsurprisingly with
        other fixtures (#517).
        """
        setup_module = _get_non_fixture_func(self.obj, "setUpModule")
        if setup_module is None:
            setup_module = _get_non_fixture_func(self.obj, "setup_module")

        teardown_module = _get_non_fixture_func(self.obj, "tearDownModule")
        if teardown_module is None:
            teardown_module = _get_non_fixture_func(self.obj, "teardown_module")

        if setup_module is None and teardown_module is None:
            return

        @fixtures.fixture(autouse=True, scope="module")
        def xunit_setup_module_fixture(request):
            if setup_module is not None:
                _call_with_optional_argument(setup_module, request.module)
            yield
            if teardown_module is not None:
                _call_with_optional_argument(teardown_module, request.module)

        self.obj.__pytest_setup_module = xunit_setup_module_fixture

    def _inject_setup_function_fixture(self):
        """Injects a hidden autouse, function scoped fixture into the collected module object
        that invokes setup_function/teardown_function if either or both are available.

        Using a fixture to invoke this methods ensures we play nicely and unsurprisingly with
        other fixtures (#517).
        """
        setup_function = _get_non_fixture_func(self.obj, "setup_function")
        teardown_function = _get_non_fixture_func(self.obj, "teardown_function")
        if setup_function is None and teardown_function is None:
            return

        @fixtures.fixture(autouse=True, scope="function")
        def xunit_setup_function_fixture(request):
            if request.instance is not None:
                # in this case we are bound to an instance, so we need to let
                # setup_method handle this
                yield
                return
            if setup_function is not None:
                _call_with_optional_argument(setup_function, request.function)
            yield
            if teardown_function is not None:
                _call_with_optional_argument(teardown_function, request.function)

        self.obj.__pytest_setup_function = xunit_setup_function_fixture

    def _importtestmodule(self):
        # we assume we are only called once per module
        importmode = self.config.getoption("--import-mode")
        try:
            mod = self.fspath.pyimport(ensuresyspath=importmode)
        except SyntaxError:
            raise self.CollectError(
                _pytest._code.ExceptionInfo.from_current().getrepr(style="short")
            )
        except self.fspath.ImportMismatchError:
            e = sys.exc_info()[1]
            raise self.CollectError(
                "import file mismatch:\n"
                "imported module %r has this __file__ attribute:\n"
                "  %s\n"
                "which is not the same as the test file we want to collect:\n"
                "  %s\n"
                "HINT: remove __pycache__ / .pyc files and/or use a "
                "unique basename for your test file modules" % e.args
            )
        except ImportError:
            from _pytest._code.code import ExceptionInfo

            exc_info = ExceptionInfo.from_current()
            if self.config.getoption("verbose") < 2:
                exc_info.traceback = exc_info.traceback.filter(filter_traceback)
            exc_repr = (
                exc_info.getrepr(style="short")
                if exc_info.traceback
                else exc_info.exconly()
            )
            formatted_tb = safe_str(exc_repr)
            raise self.CollectError(
                "ImportError while importing test module '{fspath}'.\n"
                "Hint: make sure your test modules/packages have valid Python names.\n"
                "Traceback:\n"
                "{traceback}".format(fspath=self.fspath, traceback=formatted_tb)
            )
        except _pytest.runner.Skipped as e:
            if e.allow_module_level:
                raise
            raise self.CollectError(
                "Using pytest.skip outside of a test is not allowed. "
                "To decorate a test function, use the @pytest.mark.skip "
                "or @pytest.mark.skipif decorators instead, and to skip a "
                "module use `pytestmark = pytest.mark.{skip,skipif}."
            )
        self.config.pluginmanager.consider_module(mod)
        return mod


class Package(Module):
    def __init__(self, fspath, parent=None, config=None, session=None, nodeid=None):
        session = parent.session
        nodes.FSCollector.__init__(
            self, fspath, parent=parent, config=config, session=session, nodeid=nodeid
        )
        self.name = fspath.dirname
        self.trace = session.trace
        self._norecursepatterns = session._norecursepatterns
        self.fspath = fspath

    def setup(self):
        # not using fixtures to call setup_module here because autouse fixtures
        # from packages are not called automatically (#4085)
        setup_module = _get_non_fixture_func(self.obj, "setUpModule")
        if setup_module is None:
            setup_module = _get_non_fixture_func(self.obj, "setup_module")
        if setup_module is not None:
            _call_with_optional_argument(setup_module, self.obj)

        teardown_module = _get_non_fixture_func(self.obj, "tearDownModule")
        if teardown_module is None:
            teardown_module = _get_non_fixture_func(self.obj, "teardown_module")
        if teardown_module is not None:
            func = partial(_call_with_optional_argument, teardown_module, self.obj)
            self.addfinalizer(func)

    def _recurse(self, dirpath):
        if dirpath.basename == "__pycache__":
            return False
        ihook = self.gethookproxy(dirpath.dirpath())
        if ihook.pytest_ignore_collect(path=dirpath, config=self.config):
            return
        for pat in self._norecursepatterns:
            if dirpath.check(fnmatch=pat):
                return False
        ihook = self.gethookproxy(dirpath)
        ihook.pytest_collect_directory(path=dirpath, parent=self)
        return True

    def gethookproxy(self, fspath):
        # check if we have the common case of running
        # hooks with all conftest.py filesall conftest.py
        pm = self.config.pluginmanager
        my_conftestmodules = pm._getconftestmodules(fspath)
        remove_mods = pm._conftest_plugins.difference(my_conftestmodules)
        if remove_mods:
            # one or more conftests are not in use at this fspath
            proxy = FSHookProxy(fspath, pm, remove_mods)
        else:
            # all plugis are active for this fspath
            proxy = self.config.hook
        return proxy

    def _collectfile(self, path, handle_dupes=True):
        assert path.isfile(), "%r is not a file (isdir=%r, exists=%r, islink=%r)" % (
            path,
            path.isdir(),
            path.exists(),
            path.islink(),
        )
        ihook = self.gethookproxy(path)
        if not self.isinitpath(path):
            if ihook.pytest_ignore_collect(path=path, config=self.config):
                return ()

        if handle_dupes:
            keepduplicates = self.config.getoption("keepduplicates")
            if not keepduplicates:
                duplicate_paths = self.config.pluginmanager._duplicatepaths
                if path in duplicate_paths:
                    return ()
                else:
                    duplicate_paths.add(path)

        if self.fspath == path:  # __init__.py
            return [self]

        return ihook.pytest_collect_file(path=path, parent=self)

    def isinitpath(self, path):
        return path in self.session._initialpaths

    def collect(self):
        this_path = self.fspath.dirpath()
        init_module = this_path.join("__init__.py")
        if init_module.check(file=1) and path_matches_patterns(
            init_module, self.config.getini("python_files")
        ):
            yield Module(init_module, self)
        pkg_prefixes = set()
        for path in this_path.visit(rec=self._recurse, bf=True, sort=True):
            # We will visit our own __init__.py file, in which case we skip it.
            is_file = path.isfile()
            if is_file:
                if path.basename == "__init__.py" and path.dirpath() == this_path:
                    continue

            parts_ = parts(path.strpath)
            if any(
                pkg_prefix in parts_ and pkg_prefix.join("__init__.py") != path
                for pkg_prefix in pkg_prefixes
            ):
                continue

            if is_file:
                for x in self._collectfile(path):
                    yield x
            elif not path.isdir():
                # Broken symlink or invalid/missing file.
                continue
            elif path.join("__init__.py").check(file=1):
                pkg_prefixes.add(path)


def _get_xunit_setup_teardown(holder, attr_name, param_obj=None):
    """
    Return a callable to perform xunit-style setup or teardown if
    the function exists in the ``holder`` object.
    The ``param_obj`` parameter is the parameter which will be passed to the function
    when the callable is called without arguments, defaults to the ``holder`` object.
    Return ``None`` if a suitable callable is not found.
    """
    # TODO: only needed because of Package!
    param_obj = param_obj if param_obj is not None else holder
    result = _get_non_fixture_func(holder, attr_name)
    if result is not None:
        arg_count = result.__code__.co_argcount
        if inspect.ismethod(result):
            arg_count -= 1
        if arg_count:
            return lambda: result(param_obj)
        else:
            return result


def _call_with_optional_argument(func, arg):
    """Call the given function with the given argument if func accepts one argument, otherwise
    calls func without arguments"""
    arg_count = func.__code__.co_argcount
    if inspect.ismethod(func):
        arg_count -= 1
    if arg_count:
        func(arg)
    else:
        func()


def _get_non_fixture_func(obj, name):
    """Return the attribute from the given object to be used as a setup/teardown
    xunit-style function, but only if not marked as a fixture to
    avoid calling it twice.
    """
    meth = getattr(obj, name, None)
    if fixtures.getfixturemarker(meth) is None:
        return meth


class Class(PyCollector):
    """ Collector for test methods. """

    def collect(self):
        if not safe_getattr(self.obj, "__test__", True):
            return []
        if hasinit(self.obj):
            self.warn(
                PytestWarning(
                    "cannot collect test class %r because it has a "
                    "__init__ constructor" % self.obj.__name__
                )
            )
            return []
        elif hasnew(self.obj):
            self.warn(
                PytestWarning(
                    "cannot collect test class %r because it has a "
                    "__new__ constructor" % self.obj.__name__
                )
            )
            return []

        self._inject_setup_class_fixture()
        self._inject_setup_method_fixture()

        return [Instance(name="()", parent=self)]

    def _inject_setup_class_fixture(self):
        """Injects a hidden autouse, class scoped fixture into the collected class object
        that invokes setup_class/teardown_class if either or both are available.

        Using a fixture to invoke this methods ensures we play nicely and unsurprisingly with
        other fixtures (#517).
        """
        setup_class = _get_non_fixture_func(self.obj, "setup_class")
        teardown_class = getattr(self.obj, "teardown_class", None)
        if setup_class is None and teardown_class is None:
            return

        @fixtures.fixture(autouse=True, scope="class")
        def xunit_setup_class_fixture(cls):
            if setup_class is not None:
                func = getimfunc(setup_class)
                _call_with_optional_argument(func, self.obj)
            yield
            if teardown_class is not None:
                func = getimfunc(teardown_class)
                _call_with_optional_argument(func, self.obj)

        self.obj.__pytest_setup_class = xunit_setup_class_fixture

    def _inject_setup_method_fixture(self):
        """Injects a hidden autouse, function scoped fixture into the collected class object
        that invokes setup_method/teardown_method if either or both are available.

        Using a fixture to invoke this methods ensures we play nicely and unsurprisingly with
        other fixtures (#517).
        """
        setup_method = _get_non_fixture_func(self.obj, "setup_method")
        teardown_method = getattr(self.obj, "teardown_method", None)
        if setup_method is None and teardown_method is None:
            return

        @fixtures.fixture(autouse=True, scope="function")
        def xunit_setup_method_fixture(self, request):
            method = request.function
            if setup_method is not None:
                func = getattr(self, "setup_method")
                _call_with_optional_argument(func, method)
            yield
            if teardown_method is not None:
                func = getattr(self, "teardown_method")
                _call_with_optional_argument(func, method)

        self.obj.__pytest_setup_method = xunit_setup_method_fixture


class Instance(PyCollector):
    _ALLOW_MARKERS = False  # hack, destroy later
    # instances share the object with their parents in a way
    # that duplicates markers instances if not taken out
    # can be removed at node structure reorganization time

    def _getobj(self):
        return self.parent.obj()

    def collect(self):
        self.session._fixturemanager.parsefactories(self)
        return super(Instance, self).collect()

    def newinstance(self):
        self.obj = self._getobj()
        return self.obj


class FunctionMixin(PyobjMixin):
    """ mixin for the code common to Function and Generator.
    """

    def setup(self):
        """ perform setup for this test function. """
        if isinstance(self.parent, Instance):
            self.parent.newinstance()
            self.obj = self._getobj()

    def _prunetraceback(self, excinfo):
        if hasattr(self, "_obj") and not self.config.option.fulltrace:
            code = _pytest._code.Code(get_real_func(self.obj))
            path, firstlineno = code.path, code.firstlineno
            traceback = excinfo.traceback
            ntraceback = traceback.cut(path=path, firstlineno=firstlineno)
            if ntraceback == traceback:
                ntraceback = ntraceback.cut(path=path)
                if ntraceback == traceback:
                    ntraceback = ntraceback.filter(filter_traceback)
                    if not ntraceback:
                        ntraceback = traceback

            excinfo.traceback = ntraceback.filter()
            # issue364: mark all but first and last frames to
            # only show a single-line message for each frame
            if self.config.option.tbstyle == "auto":
                if len(excinfo.traceback) > 2:
                    for entry in excinfo.traceback[1:-1]:
                        entry.set_repr_style("short")

    def repr_failure(self, excinfo, outerr=None):
        assert outerr is None, "XXX outerr usage is deprecated"
        style = self.config.option.tbstyle
        if style == "auto":
            style = "long"
        return self._repr_failure_py(excinfo, style=style)


def hasinit(obj):
    init = getattr(obj, "__init__", None)
    if init:
        return init != object.__init__


def hasnew(obj):
    new = getattr(obj, "__new__", None)
    if new:
        return new != object.__new__


class CallSpec2(object):
    def __init__(self, metafunc):
        self.metafunc = metafunc
        self.funcargs = {}
        self._idlist = []
        self.params = {}
        self._globalid = NOTSET
        self._globalparam = NOTSET
        self._arg2scopenum = {}  # used for sorting parametrized resources
        self.marks = []
        self.indices = {}

    def copy(self):
        cs = CallSpec2(self.metafunc)
        cs.funcargs.update(self.funcargs)
        cs.params.update(self.params)
        cs.marks.extend(self.marks)
        cs.indices.update(self.indices)
        cs._arg2scopenum.update(self._arg2scopenum)
        cs._idlist = list(self._idlist)
        cs._globalid = self._globalid
        cs._globalparam = self._globalparam
        return cs

    def _checkargnotcontained(self, arg):
        if arg in self.params or arg in self.funcargs:
            raise ValueError("duplicate %r" % (arg,))

    def getparam(self, name):
        try:
            return self.params[name]
        except KeyError:
            if self._globalparam is NOTSET:
                raise ValueError(name)
            return self._globalparam

    @property
    def id(self):
        return "-".join(map(str, filter(None, self._idlist)))

    def setmulti2(self, valtypes, argnames, valset, id, marks, scopenum, param_index):
        for arg, val in zip(argnames, valset):
            self._checkargnotcontained(arg)
            valtype_for_arg = valtypes[arg]
            getattr(self, valtype_for_arg)[arg] = val
            self.indices[arg] = param_index
            self._arg2scopenum[arg] = scopenum
        self._idlist.append(id)
        self.marks.extend(normalize_mark_list(marks))

    def setall(self, funcargs, id, param):
        for x in funcargs:
            self._checkargnotcontained(x)
        self.funcargs.update(funcargs)
        if id is not NOTSET:
            self._idlist.append(id)
        if param is not NOTSET:
            assert self._globalparam is NOTSET
            self._globalparam = param
        for arg in funcargs:
            self._arg2scopenum[arg] = fixtures.scopenum_function


class Metafunc(fixtures.FuncargnamesCompatAttr):
    """
    Metafunc objects are passed to the :func:`pytest_generate_tests <_pytest.hookspec.pytest_generate_tests>` hook.
    They help to inspect a test function and to generate tests according to
    test configuration or values specified in the class or module where a
    test function is defined.
    """

    def __init__(self, definition, fixtureinfo, config, cls=None, module=None):
        assert (
            isinstance(definition, FunctionDefinition)
            or type(definition).__name__ == "DefinitionMock"
        )
        self.definition = definition

        #: access to the :class:`_pytest.config.Config` object for the test session
        self.config = config

        #: the module object where the test function is defined in.
        self.module = module

        #: underlying python test function
        self.function = definition.obj

        #: set of fixture names required by the test function
        self.fixturenames = fixtureinfo.names_closure

        #: class object where the test function is defined in or ``None``.
        self.cls = cls

        self._calls = []
        self._ids = set()
        self._arg2fixturedefs = fixtureinfo.name2fixturedefs

    def parametrize(self, argnames, argvalues, indirect=False, ids=None, scope=None):
        """ Add new invocations to the underlying test function using the list
        of argvalues for the given argnames.  Parametrization is performed
        during the collection phase.  If you need to setup expensive resources
        see about setting indirect to do it rather at test setup time.

        :arg argnames: a comma-separated string denoting one or more argument
                       names, or a list/tuple of argument strings.

        :arg argvalues: The list of argvalues determines how often a
            test is invoked with different argument values.  If only one
            argname was specified argvalues is a list of values.  If N
            argnames were specified, argvalues must be a list of N-tuples,
            where each tuple-element specifies a value for its respective
            argname.

        :arg indirect: The list of argnames or boolean. A list of arguments'
            names (subset of argnames). If True the list contains all names from
            the argnames. Each argvalue corresponding to an argname in this list will
            be passed as request.param to its respective argname fixture
            function so that it can perform more expensive setups during the
            setup phase of a test rather than at collection time.

        :arg ids: list of string ids, or a callable.
            If strings, each is corresponding to the argvalues so that they are
            part of the test id. If None is given as id of specific test, the
            automatically generated id for that argument will be used.
            If callable, it should take one argument (a single argvalue) and return
            a string or return None. If None, the automatically generated id for that
            argument will be used.
            If no ids are provided they will be generated automatically from
            the argvalues.

        :arg scope: if specified it denotes the scope of the parameters.
            The scope is used for grouping tests by parameter instances.
            It will also override any fixture-function defined scope, allowing
            to set a dynamic scope using test context or configuration.
        """
        from _pytest.fixtures import scope2index
        from _pytest.mark import ParameterSet

        argnames, parameters = ParameterSet._for_parametrize(
            argnames,
            argvalues,
            self.function,
            self.config,
            function_definition=self.definition,
        )
        del argvalues

        if scope is None:
            scope = _find_parametrized_scope(argnames, self._arg2fixturedefs, indirect)

        self._validate_if_using_arg_names(argnames, indirect)

        arg_values_types = self._resolve_arg_value_types(argnames, indirect)

        ids = self._resolve_arg_ids(argnames, ids, parameters, item=self.definition)

        scopenum = scope2index(
            scope, descr="parametrize() call in {}".format(self.function.__name__)
        )

        # create the new calls: if we are parametrize() multiple times (by applying the decorator
        # more than once) then we accumulate those calls generating the cartesian product
        # of all calls
        newcalls = []
        for callspec in self._calls or [CallSpec2(self)]:
            for param_index, (param_id, param_set) in enumerate(zip(ids, parameters)):
                newcallspec = callspec.copy()
                newcallspec.setmulti2(
                    arg_values_types,
                    argnames,
                    param_set.values,
                    param_id,
                    param_set.marks,
                    scopenum,
                    param_index,
                )
                newcalls.append(newcallspec)
        self._calls = newcalls

    def _resolve_arg_ids(self, argnames, ids, parameters, item):
        """Resolves the actual ids for the given argnames, based on the ``ids`` parameter given
        to ``parametrize``.

        :param List[str] argnames: list of argument names passed to ``parametrize()``.
        :param ids: the ids parameter of the parametrized call (see docs).
        :param List[ParameterSet] parameters: the list of parameter values, same size as ``argnames``.
        :param Item item: the item that generated this parametrized call.
        :rtype: List[str]
        :return: the list of ids for each argname given
        """
        from _pytest._io.saferepr import saferepr

        idfn = None
        if callable(ids):
            idfn = ids
            ids = None
        if ids:
            func_name = self.function.__name__
            if len(ids) != len(parameters):
                msg = "In {}: {} parameter sets specified, with different number of ids: {}"
                fail(msg.format(func_name, len(parameters), len(ids)), pytrace=False)
            for id_value in ids:
                if id_value is not None and not isinstance(id_value, six.string_types):
                    msg = "In {}: ids must be list of strings, found: {} (type: {!r})"
                    fail(
                        msg.format(func_name, saferepr(id_value), type(id_value)),
                        pytrace=False,
                    )
        ids = idmaker(argnames, parameters, idfn, ids, self.config, item=item)
        return ids

    def _resolve_arg_value_types(self, argnames, indirect):
        """Resolves if each parametrized argument must be considered a parameter to a fixture or a "funcarg"
        to the function, based on the ``indirect`` parameter of the parametrized() call.

        :param List[str] argnames: list of argument names passed to ``parametrize()``.
        :param indirect: same ``indirect`` parameter of ``parametrize()``.
        :rtype: Dict[str, str]
            A dict mapping each arg name to either:
            * "params" if the argname should be the parameter of a fixture of the same name.
            * "funcargs" if the argname should be a parameter to the parametrized test function.
        """
        valtypes = {}
        if indirect is True:
            valtypes = dict.fromkeys(argnames, "params")
        elif indirect is False:
            valtypes = dict.fromkeys(argnames, "funcargs")
        elif isinstance(indirect, (tuple, list)):
            valtypes = dict.fromkeys(argnames, "funcargs")
            for arg in indirect:
                if arg not in argnames:
                    fail(
                        "In {}: indirect fixture '{}' doesn't exist".format(
                            self.function.__name__, arg
                        ),
                        pytrace=False,
                    )
                valtypes[arg] = "params"
        return valtypes

    def _validate_if_using_arg_names(self, argnames, indirect):
        """
        Check if all argnames are being used, by default values, or directly/indirectly.

        :param List[str] argnames: list of argument names passed to ``parametrize()``.
        :param indirect: same ``indirect`` parameter of ``parametrize()``.
        :raise ValueError: if validation fails.
        """
        default_arg_names = set(get_default_arg_names(self.function))
        func_name = self.function.__name__
        for arg in argnames:
            if arg not in self.fixturenames:
                if arg in default_arg_names:
                    fail(
                        "In {}: function already takes an argument '{}' with a default value".format(
                            func_name, arg
                        ),
                        pytrace=False,
                    )
                else:
                    if isinstance(indirect, (tuple, list)):
                        name = "fixture" if arg in indirect else "argument"
                    else:
                        name = "fixture" if indirect else "argument"
                    fail(
                        "In {}: function uses no {} '{}'".format(func_name, name, arg),
                        pytrace=False,
                    )


def _find_parametrized_scope(argnames, arg2fixturedefs, indirect):
    """Find the most appropriate scope for a parametrized call based on its arguments.

    When there's at least one direct argument, always use "function" scope.

    When a test function is parametrized and all its arguments are indirect
    (e.g. fixtures), return the most narrow scope based on the fixtures used.

    Related to issue #1832, based on code posted by @Kingdread.
    """
    from _pytest.fixtures import scopes

    if isinstance(indirect, (list, tuple)):
        all_arguments_are_fixtures = len(indirect) == len(argnames)
    else:
        all_arguments_are_fixtures = bool(indirect)

    if all_arguments_are_fixtures:
        fixturedefs = arg2fixturedefs or {}
        used_scopes = [
            fixturedef[0].scope
            for name, fixturedef in fixturedefs.items()
            if name in argnames
        ]
        if used_scopes:
            # Takes the most narrow scope from used fixtures
            for scope in reversed(scopes):
                if scope in used_scopes:
                    return scope

    return "function"


def _idval(val, argname, idx, idfn, item, config):
    if idfn:
        try:
            generated_id = idfn(val)
            if generated_id is not None:
                val = generated_id
        except Exception as e:
            # See issue https://github.com/pytest-dev/pytest/issues/2169
            msg = "{}: error raised while trying to determine id of parameter '{}' at position {}\n"
            msg = msg.format(item.nodeid, argname, idx)
            # we only append the exception type and message because on Python 2 reraise does nothing
            msg += "  {}: {}\n".format(type(e).__name__, e)
            six.raise_from(ValueError(msg), e)
    elif config:
        hook_id = config.hook.pytest_make_parametrize_id(
            config=config, val=val, argname=argname
        )
        if hook_id:
            return hook_id

    if isinstance(val, STRING_TYPES):
        return ascii_escaped(val)
    elif isinstance(val, (float, int, bool, NoneType)):
        return str(val)
    elif isinstance(val, REGEX_TYPE):
        return ascii_escaped(val.pattern)
    elif enum is not None and isinstance(val, enum.Enum):
        return str(val)
    elif (isclass(val) or isfunction(val)) and hasattr(val, "__name__"):
        return val.__name__
    return str(argname) + str(idx)


def _idvalset(idx, parameterset, argnames, idfn, ids, item, config):
    if parameterset.id is not None:
        return parameterset.id
    if ids is None or (idx >= len(ids) or ids[idx] is None):
        this_id = [
            _idval(val, argname, idx, idfn, item=item, config=config)
            for val, argname in zip(parameterset.values, argnames)
        ]
        return "-".join(this_id)
    else:
        return ascii_escaped(ids[idx])


def idmaker(argnames, parametersets, idfn=None, ids=None, config=None, item=None):
    ids = [
        _idvalset(valindex, parameterset, argnames, idfn, ids, config=config, item=item)
        for valindex, parameterset in enumerate(parametersets)
    ]
    if len(set(ids)) != len(ids):
        # The ids are not unique
        duplicates = [testid for testid in ids if ids.count(testid) > 1]
        counters = collections.defaultdict(lambda: 0)
        for index, testid in enumerate(ids):
            if testid in duplicates:
                ids[index] = testid + str(counters[testid])
                counters[testid] += 1
    return ids


def show_fixtures_per_test(config):
    from _pytest.main import wrap_session

    return wrap_session(config, _show_fixtures_per_test)


def _show_fixtures_per_test(config, session):
    import _pytest.config

    session.perform_collect()
    curdir = py.path.local()
    tw = _pytest.config.create_terminal_writer(config)
    verbose = config.getvalue("verbose")

    def get_best_relpath(func):
        loc = getlocation(func, curdir)
        return curdir.bestrelpath(loc)

    def write_fixture(fixture_def):
        argname = fixture_def.argname
        if verbose <= 0 and argname.startswith("_"):
            return
        if verbose > 0:
            bestrel = get_best_relpath(fixture_def.func)
            funcargspec = "{} -- {}".format(argname, bestrel)
        else:
            funcargspec = argname
        tw.line(funcargspec, green=True)
        fixture_doc = fixture_def.func.__doc__
        if fixture_doc:
            write_docstring(tw, fixture_doc)
        else:
            tw.line("    no docstring available", red=True)

    def write_item(item):
        try:
            info = item._fixtureinfo
        except AttributeError:
            # doctests items have no _fixtureinfo attribute
            return
        if not info.name2fixturedefs:
            # this test item does not use any fixtures
            return
        tw.line()
        tw.sep("-", "fixtures used by {}".format(item.name))
        tw.sep("-", "({})".format(get_best_relpath(item.function)))
        # dict key not used in loop but needed for sorting
        for _, fixturedefs in sorted(info.name2fixturedefs.items()):
            assert fixturedefs is not None
            if not fixturedefs:
                continue
            # last item is expected to be the one used by the test item
            write_fixture(fixturedefs[-1])

    for session_item in session.items:
        write_item(session_item)


def showfixtures(config):
    from _pytest.main import wrap_session

    return wrap_session(config, _showfixtures_main)


def _showfixtures_main(config, session):
    import _pytest.config

    session.perform_collect()
    curdir = py.path.local()
    tw = _pytest.config.create_terminal_writer(config)
    verbose = config.getvalue("verbose")

    fm = session._fixturemanager

    available = []
    seen = set()

    for argname, fixturedefs in fm._arg2fixturedefs.items():
        assert fixturedefs is not None
        if not fixturedefs:
            continue
        for fixturedef in fixturedefs:
            loc = getlocation(fixturedef.func, curdir)
            if (fixturedef.argname, loc) in seen:
                continue
            seen.add((fixturedef.argname, loc))
            available.append(
                (
                    len(fixturedef.baseid),
                    fixturedef.func.__module__,
                    curdir.bestrelpath(loc),
                    fixturedef.argname,
                    fixturedef,
                )
            )

    available.sort()
    currentmodule = None
    for baseid, module, bestrel, argname, fixturedef in available:
        if currentmodule != module:
            if not module.startswith("_pytest."):
                tw.line()
                tw.sep("-", "fixtures defined from %s" % (module,))
                currentmodule = module
        if verbose <= 0 and argname[0] == "_":
            continue
        if verbose > 0:
            funcargspec = "%s -- %s" % (argname, bestrel)
        else:
            funcargspec = argname
        tw.line(funcargspec, green=True)
        loc = getlocation(fixturedef.func, curdir)
        doc = fixturedef.func.__doc__ or ""
        if doc:
            write_docstring(tw, doc)
        else:
            tw.line("    %s: no docstring available" % (loc,), red=True)


def write_docstring(tw, doc, indent="    "):
    doc = doc.rstrip()
    if "\n" in doc:
        firstline, rest = doc.split("\n", 1)
    else:
        firstline, rest = doc, ""

    if firstline.strip():
        tw.line(indent + firstline.strip())

    if rest:
        for line in dedent(rest).split("\n"):
            tw.write(indent + line + "\n")


class Function(FunctionMixin, nodes.Item, fixtures.FuncargnamesCompatAttr):
    """ a Function Item is responsible for setting up and executing a
    Python test function.
    """

    # disable since functions handle it themselves
    _ALLOW_MARKERS = False

    def __init__(
        self,
        name,
        parent,
        args=None,
        config=None,
        callspec=None,
        callobj=NOTSET,
        keywords=None,
        session=None,
        fixtureinfo=None,
        originalname=None,
    ):
        super(Function, self).__init__(name, parent, config=config, session=session)
        self._args = args
        if callobj is not NOTSET:
            self.obj = callobj

        self.keywords.update(self.obj.__dict__)
        self.own_markers.extend(get_unpacked_marks(self.obj))
        if callspec:
            self.callspec = callspec
            # this is total hostile and a mess
            # keywords are broken by design by now
            # this will be redeemed later
            for mark in callspec.marks:
                # feel free to cry, this was broken for years before
                # and keywords cant fix it per design
                self.keywords[mark.name] = mark
            self.own_markers.extend(normalize_mark_list(callspec.marks))
        if keywords:
            self.keywords.update(keywords)

        # todo: this is a hell of a hack
        # https://github.com/pytest-dev/pytest/issues/4569

        self.keywords.update(
            dict.fromkeys(
                [
                    mark.name
                    for mark in self.iter_markers()
                    if mark.name not in self.keywords
                ],
                True,
            )
        )

        if fixtureinfo is None:
            fixtureinfo = self.session._fixturemanager.getfixtureinfo(
                self, self.obj, self.cls, funcargs=True
            )
        self._fixtureinfo = fixtureinfo
        self.fixturenames = fixtureinfo.names_closure
        self._initrequest()

        #: original function name, without any decorations (for example
        #: parametrization adds a ``"[...]"`` suffix to function names).
        #:
        #: .. versionadded:: 3.0
        self.originalname = originalname

    def _initrequest(self):
        self.funcargs = {}
        self._request = fixtures.FixtureRequest(self)

    @property
    def function(self):
        "underlying python 'function' object"
        return getimfunc(self.obj)

    def _getobj(self):
        name = self.name
        i = name.find("[")  # parametrization
        if i != -1:
            name = name[:i]
        return getattr(self.parent.obj, name)

    @property
    def _pyfuncitem(self):
        "(compatonly) for code expecting pytest-2.2 style request objects"
        return self

    def runtest(self):
        """ execute the underlying test function. """
        self.ihook.pytest_pyfunc_call(pyfuncitem=self)

    def setup(self):
        super(Function, self).setup()
        fixtures.fillfixtures(self)


class FunctionDefinition(Function):
    """
    internal hack until we get actual definition nodes instead of the
    crappy metafunc hack
    """

    def runtest(self):
        raise RuntimeError("function definitions are not supposed to be used")

    setup = runtest