Feed a test only with initialnames, not the whole fixture closure

changelog/11284.deprecation.rst

@@ -0,0 +1,3 @@
+Accessing ``item.funcargs`` with fixture names other than the direct ones, i.e. the direct args, the ones with ``autouse`` and the ones with ``usefixtures`` issues a warning.
+
+This will become an error in pytest 9.

doc/en/deprecations.rst

@@ -278,6 +278,17 @@ The accompanying ``py.path.local`` based paths have been deprecated: plugins whi
     resolved in future versions as we slowly get rid of the :pypi:`py`
     dependency (see :issue:`9283` for a longer discussion).
 
+.. _item-funcargs-deprecation:
+
+Accessing ``item.funcargs`` with non-directly requested fixture names
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionremoved:: 8.1
+
+Accessing ``item.funcargs`` with non-directly requested fixture names issues a warning and will be erroneous starting from pytest 9.
+Directly requested fixtures are the direct arguments to the test, ``usefixtures`` fixtures and ``autouse`` fixtures.
+
+To request a fixture other than the directly requested ones, use :func:`request.getfixturevalue <pytest.FixtureRequest.getfixturevalue>` instead.
 
 .. _nose-deprecation:
 

doc/en/example/simple.rst

@@ -818,7 +818,7 @@ case we just write some information out to a ``failures`` file:
             mode = "a" if os.path.exists("failures") else "w"
             with open("failures", mode, encoding="utf-8") as f:
                 # let's also access a fixture for the fun of it
-                if "tmp_path" in item.fixturenames:
+                if "tmp_path" in item.funcargs:
                     extra = " ({})".format(item.funcargs["tmp_path"])
                 else:
                     extra = ""

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/deprecated.py

@@ -48,6 +48,13 @@
     "See docs: https://docs.pytest.org/en/stable/deprecations.html#applying-a-mark-to-a-fixture-function"
 )
 
+ITEM_FUNCARGS_MEMBERS = PytestRemovedIn9Warning(
+    "Accessing `item.funcargs` with a fixture name not directly requested"
+    " by the item, through a direct argument, `usefixtures` marker or"
+    " an `autouse` fixture, is deprecated and will raise KeyError starting"
+    " from pytest 9. Please use request.getfixturevalue instead."
+)
+
 # You want to make some `__init__` or function "private".
 #
 #   def my_private_function(some, args):

src/_pytest/doctest.py

@@ -40,6 +40,7 @@
 from _pytest.outcomes import skip
 from _pytest.pathlib import fnmatch_ex
 from _pytest.pathlib import import_path
+from _pytest.python import DeprecatingFuncArgs
 from _pytest.python import Module
 from _pytest.python_api import approx
 from _pytest.warning_types import PytestWarning
@@ -284,7 +285,9 @@ def from_parent(  # type: ignore
         return super().from_parent(name=name, parent=parent, runner=runner, dtest=dtest)
 
     def _initrequest(self) -> None:
-        self.funcargs: Dict[str, object] = {}
+        self.funcargs: Dict[str, object] = DeprecatingFuncArgs(
+            self._fixtureinfo.initialnames
+        )
         self._request = TopRequest(self, _ispytest=True)  # type: ignore[arg-type]
 
     def setup(self) -> None:

src/_pytest/fixtures.py

@@ -682,7 +682,8 @@ def __repr__(self) -> str:
 
     def _fillfixtures(self) -> None:
         item = self._pyfuncitem
-        for argname in item.fixturenames:
+        fixturenames = getattr(item, "fixturenames", self.fixturenames)
+        for argname in fixturenames:
             if argname not in item.funcargs:
                 item.funcargs[argname] = self.getfixturevalue(argname)
 

src/_pytest/python.py

@@ -15,6 +15,7 @@
 from typing import Any
 from typing import Callable
 from typing import Dict
+from typing import Final
 from typing import final
 from typing import Generator
 from typing import Iterable
@@ -55,6 +56,7 @@
 from _pytest.config import hookimpl
 from _pytest.config.argparsing import Parser
 from _pytest.deprecated import check_ispytest
+from _pytest.deprecated import ITEM_FUNCARGS_MEMBERS
 from _pytest.fixtures import FixtureDef
 from _pytest.fixtures import FixtureRequest
 from _pytest.fixtures import FuncFixtureInfo
@@ -1657,6 +1659,19 @@ def write_docstring(tw: TerminalWriter, doc: str, indent: str = "    ") -> None:
         tw.line(indent + line)
 
 
+class DeprecatingFuncArgs(Dict[str, object]):
+    def __init__(self, initialnames: Sequence[str]) -> None:
+        super().__init__()
+        self.warned: bool = False
+        self.initialnames: Final = initialnames
+
+    def __getitem__(self, key: str) -> object:
+        if not self.warned and key not in self.initialnames:
+            self.warned = True
+            warnings.warn(ITEM_FUNCARGS_MEMBERS, stacklevel=2)
+        return super().__getitem__(key)
+
+
 class Function(PyobjMixin, nodes.Item):
     """Item responsible for setting up and executing a Python test function.
 
@@ -1745,7 +1760,9 @@ def from_parent(cls, parent, **kw):  # todo: determine sound type limitations
         return super().from_parent(parent=parent, **kw)
 
     def _initrequest(self) -> None:
-        self.funcargs: Dict[str, object] = {}
+        self.funcargs: Dict[str, object] = DeprecatingFuncArgs(
+            self._fixtureinfo.initialnames
+        )
         self._request = fixtures.TopRequest(self, _ispytest=True)
 
     @property

testing/deprecated_test.py

@@ -133,3 +133,32 @@ def foo():
             raise NotImplementedError()
 
     assert len(record) == 2  # one for each mark decorator
+
+
+def test_deprecated_access_to_item_funcargs(pytester: Pytester) -> None:
+    pytester.makepyfile(
+        """
+        import pytest
+
+        @pytest.fixture
+        def fixture1():
+            return None
+
+        @pytest.fixture
+        def fixture2(fixture1):
+            return None
+
+        def test(request, fixture2):
+            with pytest.warns(
+                pytest.PytestRemovedIn9Warning,
+                match=r"Accessing `item.funcargs` with a fixture",
+            ) as record:
+                request.node.funcargs["fixture1"]
+                assert request.node.funcargs.warned
+                request.node.funcargs.warned = False
+                request.node.funcargs["fixture2"]
+            assert len(record) == 1
+        """
+    )
+    output = pytester.runpytest()
+    output.assert_outcomes(passed=1)

testing/test_doctest.py

@@ -881,6 +881,41 @@ def test_foo():
         result = pytester.runpytest(p, "--doctest-modules")
         result.stdout.fnmatch_lines(["*collected 1 item*"])
 
+    def test_deprecated_access_to_item_funcargs(self, pytester: Pytester):
+        pytester.makeconftest(
+            """
+            import pytest
+
+            @pytest.fixture
+            def fixture1():
+                return None
+
+            @pytest.fixture(autouse=True)
+            def fixture2(fixture1):
+                return None
+        """
+        )
+        pytester.makepyfile(
+            """
+            '''
+                >>> import pytest
+                >>> request = getfixture('request')
+                >>> with pytest.warns(
+                ...     pytest.PytestRemovedIn9Warning,
+                ...    match=r"Accessing `item.funcargs` with a fixture",
+                ... ) as record:
+                ...     request.node.funcargs["fixture1"]
+                ...     assert request.node.funcargs.warned
+                ...     request.node.funcargs.warned = False
+                ...     request.node.funcargs["fixture2"]
+                >>> len(record)
+                1
+            '''
+        """
+        )
+        result = pytester.runpytest("--doctest-modules")
+        result.assert_outcomes(passed=1)
+
 
 class TestLiterals:
     @pytest.mark.parametrize("config_mode", ["ini", "comment"])