Remove prune_dependency_tree and reuse getfixtureclosure logic

src/_pytest/assertion/rewrite.py

@@ -17,6 +17,7 @@
 from pathlib import Path
 from pathlib import PurePath
 from typing import Callable
+from typing import DefaultDict
 from typing import Dict
 from typing import IO
 from typing import Iterable
@@ -668,9 +669,9 @@ def __init__(
         else:
             self.enable_assertion_pass_hook = False
         self.source = source
-        self.scope: tuple[ast.AST, ...] = ()
-        self.variables_overwrite: defaultdict[
-            tuple[ast.AST, ...], Dict[str, str]
+        self.scope: Tuple[ast.AST, ...] = ()
+        self.variables_overwrite: DefaultDict[
+            Tuple[ast.AST, ...], Dict[str, str]
         ] = defaultdict(dict)
 
     def run(self, mod: ast.Module) -> None:

src/_pytest/fixtures.py

@@ -314,33 +314,6 @@ class FuncFixtureInfo:
     # sequence is ordered from furthest to closes to the function.
     name2fixturedefs: Dict[str, Sequence["FixtureDef[Any]"]]
 
-    def prune_dependency_tree(self) -> None:
-        """Recompute names_closure from initialnames and name2fixturedefs.
-
-        Can only reduce names_closure, which means that the new closure will
-        always be a subset of the old one. The order is preserved.
-
-        This method is needed because direct parametrization may shadow some
-        of the fixtures that were included in the originally built dependency
-        tree. In this way the dependency tree can get pruned, and the closure
-        of argnames may get reduced.
-        """
-        closure: Set[str] = set()
-        working_set = set(self.initialnames)
-        while working_set:
-            argname = working_set.pop()
-            # Argname may be smth not included in the original names_closure,
-            # in which case we ignore it. This currently happens with pseudo
-            # FixtureDefs which wrap 'get_direct_param_fixture_func(request)'.
-            # So they introduce the new dependency 'request' which might have
-            # been missing in the original tree (closure).
-            if argname not in closure and argname in self.names_closure:
-                closure.add(argname)
-                if argname in self.name2fixturedefs:
-                    working_set.update(self.name2fixturedefs[argname][-1].argnames)
-
-        self.names_closure[:] = sorted(closure, key=self.names_closure.index)
-
 
 class FixtureRequest(abc.ABC):
     """The type of the ``request`` fixture.
@@ -961,7 +934,6 @@ def _eval_scope_callable(
     return result
 
 
-@final
 class FixtureDef(Generic[FixtureValue]):
     """A container for a fixture definition.
 
@@ -1104,6 +1076,26 @@ def __repr__(self) -> str:
         )
 
 
+class IdentityFixtureDef(FixtureDef[FixtureValue]):
+    def __init__(
+        self,
+        fixturemanager: "FixtureManager",
+        argname: str,
+        scope: Union[Scope, _ScopeName, Callable[[str, Config], _ScopeName], None],
+        *,
+        _ispytest: bool = False,
+    ):
+        super().__init__(
+            fixturemanager,
+            "",
+            argname,
+            lambda request: request.param,
+            scope,
+            None,
+            _ispytest=_ispytest,
+        )
+
+
 def resolve_fixture_function(
     fixturedef: FixtureDef[FixtureValue], request: FixtureRequest
 ) -> "_FixtureFunc[FixtureValue]":
@@ -1486,10 +1478,11 @@ def getfixtureinfo(
         initialnames = deduplicate_names(autousenames, usefixturesnames, argnames)
 
         direct_parametrize_args = _get_direct_parametrize_args(node)
-
-        names_closure, arg2fixturedefs = self.getfixtureclosure(
+        arg2fixturedefs: Dict[str, Sequence[FixtureDef[Any]]] = {}
+        names_closure = self.getfixtureclosure(
             parentnode=node,
             initialnames=initialnames,
+            arg2fixturedefs=arg2fixturedefs,
             ignore_args=direct_parametrize_args,
         )
 
@@ -1533,30 +1526,33 @@ def getfixtureclosure(
         self,
         parentnode: nodes.Node,
         initialnames: Tuple[str, ...],
+        arg2fixturedefs: Dict[str, Sequence[FixtureDef[Any]]],
         ignore_args: AbstractSet[str],
-    ) -> Tuple[List[str], Dict[str, Sequence[FixtureDef[Any]]]]:
+    ) -> List[str]:
         # Collect the closure of all fixtures, starting with the given
-        # fixturenames as the initial set.  As we have to visit all
-        # factory definitions anyway, we also return an arg2fixturedefs
-        # mapping so that the caller can reuse it and does not have
-        # to re-discover fixturedefs again for each fixturename
+        # initialnames containing function arguments, `usefixture` markers
+        # and `autouse` fixtures as the initial set.  As we have to visit all
+        # factory definitions anyway, we also populate arg2fixturedefs mapping
+        # for the args missing therein so that the caller can reuse it and does
+        # not have to re-discover fixturedefs again for each fixturename
         # (discovering matching fixtures for a given name/node is expensive).
 
         parentid = parentnode.nodeid
         fixturenames_closure = list(initialnames)
 
-        arg2fixturedefs: Dict[str, Sequence[FixtureDef[Any]]] = {}
         lastlen = -1
         while lastlen != len(fixturenames_closure):
             lastlen = len(fixturenames_closure)
             for argname in fixturenames_closure:
                 if argname in ignore_args:
                     continue
-                if argname in arg2fixturedefs:
-                    continue
-                fixturedefs = self.getfixturedefs(argname, parentid)
-                if fixturedefs:
-                    arg2fixturedefs[argname] = fixturedefs
+                if argname not in arg2fixturedefs:
+                    fixturedefs = self.getfixturedefs(argname, parentid)
+                    if fixturedefs:
+                        arg2fixturedefs[argname] = fixturedefs
+                else:
+                    fixturedefs = arg2fixturedefs[argname]
+                if fixturedefs and not isinstance(fixturedefs[-1], IdentityFixtureDef):
                     for arg in fixturedefs[-1].argnames:
                         if arg not in fixturenames_closure:
                             fixturenames_closure.append(arg)
@@ -1570,7 +1566,7 @@ def sort_by_scope(arg_name: str) -> Scope:
                 return fixturedefs[-1]._scope
 
         fixturenames_closure.sort(key=sort_by_scope, reverse=True)
-        return fixturenames_closure, arg2fixturedefs
+        return fixturenames_closure
 
     def pytest_generate_tests(self, metafunc: "Metafunc") -> None:
         """Generate new tests based on parametrized fixtures used by the given metafunc"""

src/_pytest/python.py

@@ -59,10 +59,10 @@
 from _pytest.deprecated import check_ispytest
 from _pytest.deprecated import INSTANCE_COLLECTOR
 from _pytest.deprecated import NOSE_SUPPORT_METHOD
-from _pytest.fixtures import FixtureDef
-from _pytest.fixtures import FixtureRequest
+from _pytest.fixtures import _get_direct_parametrize_args
 from _pytest.fixtures import FuncFixtureInfo
 from _pytest.fixtures import get_scope_node
+from _pytest.fixtures import IdentityFixtureDef
 from _pytest.main import Session
 from _pytest.mark import MARK_GEN
 from _pytest.mark import ParameterSet
@@ -479,8 +479,6 @@
         )
         fixtureinfo = definition._fixtureinfo
 
-        # pytest_generate_tests impls call metafunc.parametrize() which fills
-        # metafunc._calls, the outcome of the hook.
         metafunc = Metafunc(
             definition=definition,
             fixtureinfo=fixtureinfo,
@@ -489,23 +487,32 @@
             module=module,
             _ispytest=True,
         )
-        methods = []
+
+        def prune_dependency_tree_if_test_is_directly_parametrized(metafunc: Metafunc):
+            # Direct (those with `indirect=False`) parametrizations taking place in
+            # module/class-specific `pytest_generate_tests` hooks, a.k.a dynamic direct
+            # parametrizations using `metafunc.parametrize`, may have shadowed some
+            # fixtures, making some fixtures no longer reachable. Update the dependency
+            # tree to reflect what the item really needs.
+            # Note that direct parametrizations using `@pytest.mark.parametrize` have
+            # already been considered into making the closure using the `ignore_args`
+            # arg to `getfixtureclosure`.
+            if metafunc._has_direct_parametrization:
+                metafunc._update_dependency_tree()
+
+        methods = [prune_dependency_tree_if_test_is_directly_parametrized]
         if hasattr(module, "pytest_generate_tests"):
             methods.append(module.pytest_generate_tests)
         if cls is not None and hasattr(cls, "pytest_generate_tests"):
             methods.append(cls().pytest_generate_tests)
+
+        # pytest_generate_tests impls call metafunc.parametrize() which fills
+        # metafunc._calls, the outcome of the hook.
         self.ihook.pytest_generate_tests.call_extra(methods, dict(metafunc=metafunc))
 
         if not metafunc._calls:
             yield Function.from_parent(self, name=name, fixtureinfo=fixtureinfo)
         else:
-            # Direct parametrizations taking place in module/class-specific
-            # `metafunc.parametrize` calls may have shadowed some fixtures, so make sure
-            # we update what the function really needs a.k.a its fixture closure. Note that
-            # direct parametrizations using `@pytest.mark.parametrize` have already been considered
-            # into making the closure using `ignore_args` arg to `getfixtureclosure`.
-            fixtureinfo.prune_dependency_tree()
-
             for callspec in metafunc._calls:
                 subname = f"{name}[{callspec.id}]"
                 yield Function.from_parent(
@@ -1180,12 +1187,8 @@
         return "-".join(self._idlist)
 
 
-def get_direct_param_fixture_func(request: FixtureRequest) -> Any:
-    return request.param
-
-
 # Used for storing pseudo fixturedefs for direct parametrization.
-name2pseudofixturedef_key = StashKey[Dict[str, FixtureDef[Any]]]()
+name2pseudofixturedef_key = StashKey[Dict[str, IdentityFixtureDef[Any]]]()
 
 
 @final
@@ -1232,6 +1235,9 @@
         # Result of parametrize().
         self._calls: List[CallSpec2] = []
 
+        # Whether it's ever been directly parametrized, i.e. with `indirect=False`.
+        self._has_direct_parametrization = False
+
     def parametrize(
         self,
         argnames: Union[str, Sequence[str]],
@@ -1372,26 +1378,22 @@
         if node is None:
             name2pseudofixturedef = None
         else:
-            default: Dict[str, FixtureDef[Any]] = {}
+            default: Dict[str, IdentityFixtureDef[Any]] = {}
             name2pseudofixturedef = node.stash.setdefault(
                 name2pseudofixturedef_key, default
             )
         arg_directness = self._resolve_args_directness(argnames, indirect)
         for argname in argnames:
             if arg_directness[argname] == "indirect":
                 continue
+            self._has_direct_parametrization = True
             if name2pseudofixturedef is not None and argname in name2pseudofixturedef:
                 fixturedef = name2pseudofixturedef[argname]
             else:
-                fixturedef = FixtureDef(
-                    fixturemanager=self.definition.session._fixturemanager,
-                    baseid="",
-                    argname=argname,
-                    func=get_direct_param_fixture_func,
-                    scope=scope_,
-                    params=None,
-                    unittest=False,
-                    ids=None,
+                fixturedef = IdentityFixtureDef(
+                    self.definition.session._fixturemanager,
+                    argname,
+                    scope_,
                     _ispytest=True,
                 )
                 if name2pseudofixturedef is not None:
@@ -1557,6 +1559,18 @@
                         pytrace=False,
                     )
 
+    def _update_dependency_tree(self) -> None:
+        definition = self.definition
+        assert definition.parent is not None
+        fm = definition.parent.session._fixturemanager
+        fixture_closure = fm.getfixtureclosure(
+            parentnode=definition,
+            initialnames=definition._fixtureinfo.initialnames,
+            arg2fixturedefs=definition._fixtureinfo.name2fixturedefs,
+            ignore_args=_get_direct_parametrize_args(definition),
+        )
+        definition._fixtureinfo.names_closure[:] = fixture_closure
+
 
 def _find_parametrized_scope(
     argnames: Sequence[str],