Class FixtureManager

src/_pytest/fixtures.py:1388–1686

pytest fixture definitions and information is stored and managed from this class. During collection fm.parsefactories() is called multiple times to parse fixture function definitions into FixtureDef objects and internal data structures. During collection of test functions, meta

class FixtureManager:
    """pytest fixture definitions and information is stored and managed
    from this class.

    During collection fm.parsefactories() is called multiple times to parse
    fixture function definitions into FixtureDef objects and internal
    data structures.

    During collection of test functions, metafunc-mechanics instantiate
    a FuncFixtureInfo object which is cached per node/func-name.
    This FuncFixtureInfo object is later retrieved by Function nodes
    which themselves offer a fixturenames attribute.

    The FuncFixtureInfo object holds information about fixtures and FixtureDefs
    relevant for a particular function. An initial list of fixtures is
    assembled like this:

    - ini-defined usefixtures
    - autouse-marked fixtures along the collection chain up from the function
    - usefixtures markers at module/class/function level
    - test function funcargs

    Subsequently the funcfixtureinfo.fixturenames attribute is computed
    as the closure of the fixtures needed to setup the initial fixtures,
    i.e. fixtures needed by fixture functions themselves are appended
    to the fixturenames list.

    Upon the test-setup phases all fixturenames are instantiated, retrieved
    by a lookup of their FuncFixtureInfo.
    """

    FixtureLookupError = FixtureLookupError
    FixtureLookupErrorRepr = FixtureLookupErrorRepr

    def __init__(self, session: "Session") -> None:
        self.session = session
        self.config: Config = session.config
        self._arg2fixturedefs: Dict[str, List[FixtureDef[Any]]] = {}
        self._holderobjseen: Set[object] = set()
        # A mapping from a nodeid to a list of autouse fixtures it defines.
        self._nodeid_autousenames: Dict[str, List[str]] = {
            "": self.config.getini("usefixtures"),
        }
        session.config.pluginmanager.register(self, "funcmanage")

    def _get_direct_parametrize_args(self, node: nodes.Node) -> List[str]:
        """Return all direct parametrization arguments of a node, so we don't
        mistake them for fixtures.

        Check https://github.com/pytest-dev/pytest/issues/5036.

        These things are done later as well when dealing with parametrization
        so this could be improved.
        """
        parametrize_argnames: List[str] = []
        for marker in node.iter_markers(name="parametrize"):
            if not marker.kwargs.get("indirect", False):
                p_argnames, _ = ParameterSet._parse_parametrize_args(