Hard error when setting a mark on a fixture function

Deprecated feature scheduled for removal in pytest 9. Part of pytest-dev#13893.

Author: bluetech

doc/en/deprecations.rst

@@ -367,23 +367,6 @@ conflicts (such as :class:`pytest.File` now taking ``path`` instead of
 ``fspath``, as :ref:`outlined above <node-ctor-fspath-deprecation>`), a
 deprecation warning is now raised.
 
-Applying a mark to a fixture function
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. deprecated:: 7.4
-
-Applying a mark to a fixture function never had any effect, but it is a common user error.
-
-.. code-block:: python
-
-    @pytest.mark.usefixtures("clean_database")
-    @pytest.fixture
-    def user() -> User: ...
-
-Users expected in this case that the ``usefixtures`` mark would have its intended effect of using the ``clean_database`` fixture when ``user`` was invoked, when in fact it has no effect at all.
-
-Now pytest will issue a warning when it encounters this problem, and will raise an error in the future versions.
-
 
 The ``yield_fixture`` function/decorator
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -403,6 +386,24 @@ an appropriate period of deprecation has passed.
 
 Some breaking changes which could not be deprecated are also listed.
 
+Applying a mark to a fixture function
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. deprecated:: 7.4
+.. versionremoved:: 9.0
+
+Applying a mark to a fixture function never had any effect, but it is a common user error.
+
+.. code-block:: python
+
+    @pytest.mark.usefixtures("clean_database")
+    @pytest.fixture
+    def user() -> User: ...
+
+Users expected in this case that the ``usefixtures`` mark would have its intended effect of using the ``clean_database`` fixture when ``user`` was invoked, when in fact it has no effect at all.
+
+Now pytest will issue a warning when it encounters this problem, and will raise an error in the future versions.
+
 .. _legacy-path-hooks-deprecated:
 
 ``py.path.local`` arguments for hooks replaced with ``pathlib.Path``

src/_pytest/deprecated.py

@@ -56,11 +56,6 @@
     "#configuring-hook-specs-impls-using-markers",
 )
 
-MARKED_FIXTURE = PytestRemovedIn9Warning(
-    "Marks applied to fixtures have no effect\n"
-    "See docs: https://docs.pytest.org/en/stable/deprecations.html#applying-a-mark-to-a-fixture-function"
-)
-
 MONKEYPATCH_LEGACY_NAMESPACE_PACKAGES = PytestRemovedIn10Warning(
     "monkeypatch.syspath_prepend() called with pkg_resources legacy namespace packages detected.\n"
     "Legacy namespace packages (using pkg_resources.declare_namespace) are deprecated.\n"

src/_pytest/fixtures.py

@@ -53,7 +53,6 @@
 from _pytest.config import ExitCode
 from _pytest.config.argparsing import Parser
 from _pytest.deprecated import check_ispytest
-from _pytest.deprecated import MARKED_FIXTURE
 from _pytest.deprecated import YIELD_FIXTURE
 from _pytest.main import Session
 from _pytest.mark import Mark
@@ -1236,7 +1235,10 @@ def __call__(self, function: FixtureFunction) -> FixtureFunctionDefinition:
             )
 
         if hasattr(function, "pytestmark"):
-            warnings.warn(MARKED_FIXTURE, stacklevel=2)
+            fail(
+                "Marks cannot be applied to fixtures.\n"
+                "See docs: https://docs.pytest.org/en/stable/deprecations.html#applying-a-mark-to-a-fixture-function"
+            )
 
         fixture_definition = FixtureFunctionDefinition(
             function=function, fixture_function_marker=self, _ispytest=True

src/_pytest/mark/structures.py

@@ -26,7 +26,6 @@
 from ..compat import NotSetType
 from _pytest.config import Config
 from _pytest.deprecated import check_ispytest
-from _pytest.deprecated import MARKED_FIXTURE
 from _pytest.deprecated import PARAMETRIZE_NON_COLLECTION_ITERABLE
 from _pytest.outcomes import fail
 from _pytest.raises import AbstractRaises
@@ -409,7 +408,7 @@ def __call__(self, *args: object, **kwargs: object):
             if isinstance(func, staticmethod | classmethod):
                 unwrapped_func = func.__func__
             if len(args) == 1 and (istestfunc(unwrapped_func) or is_class):
-                store_mark(unwrapped_func, self.mark, stacklevel=3)
+                store_mark(unwrapped_func, self.mark)
                 return func
         return self.with_args(*args, **kwargs)
 
@@ -464,7 +463,7 @@ def normalize_mark_list(
         yield mark_obj
 
 
-def store_mark(obj, mark: Mark, *, stacklevel: int = 2) -> None:
+def store_mark(obj, mark: Mark) -> None:
     """Store a Mark on an object.
 
     This is used to implement the Mark declarations/decorators correctly.
@@ -474,7 +473,10 @@ def store_mark(obj, mark: Mark, *, stacklevel: int = 2) -> None:
     from ..fixtures import getfixturemarker
 
     if getfixturemarker(obj) is not None:
-        warnings.warn(MARKED_FIXTURE, stacklevel=stacklevel)
+        fail(
+            "Marks cannot be applied to fixtures.\n"
+            "See docs: https://docs.pytest.org/en/stable/deprecations.html#applying-a-mark-to-a-fixture-function"
+        )
 
     # Always reassign name to avoid updating pytestmark in a reference that
     # was only borrowed.

testing/deprecated_test.py

@@ -107,56 +107,3 @@ def collect(self):
             parent=mod.parent,
             fspath=legacy_path("bla"),
         )
-
-
-def test_fixture_disallow_on_marked_functions():
-    """Test that applying @pytest.fixture to a marked function warns (#3364)."""
-    with pytest.warns(
-        pytest.PytestRemovedIn9Warning,
-        match=r"Marks applied to fixtures have no effect",
-    ) as record:
-
-        @pytest.fixture
-        @pytest.mark.parametrize("example", ["hello"])
-        @pytest.mark.usefixtures("tmp_path")
-        def foo():
-            raise NotImplementedError()
-
-    # it's only possible to get one warning here because you're already prevented
-    # from applying @fixture twice
-    # ValueError("fixture is being applied more than once to the same function")
-    assert len(record) == 1
-
-
-def test_fixture_disallow_marks_on_fixtures():
-    """Test that applying a mark to a fixture warns (#3364)."""
-    with pytest.warns(
-        pytest.PytestRemovedIn9Warning,
-        match=r"Marks applied to fixtures have no effect",
-    ) as record:
-
-        @pytest.mark.parametrize("example", ["hello"])
-        @pytest.mark.usefixtures("tmp_path")
-        @pytest.fixture
-        def foo():
-            raise NotImplementedError()
-
-    assert len(record) == 2  # one for each mark decorator
-    # should point to this file
-    assert all(rec.filename == __file__ for rec in record)
-
-
-def test_fixture_disallowed_between_marks():
-    """Test that applying a mark to a fixture warns (#3364)."""
-    with pytest.warns(
-        pytest.PytestRemovedIn9Warning,
-        match=r"Marks applied to fixtures have no effect",
-    ) as record:
-
-        @pytest.mark.parametrize("example", ["hello"])
-        @pytest.fixture
-        @pytest.mark.usefixtures("tmp_path")
-        def foo():
-            raise NotImplementedError()
-
-    assert len(record) == 2  # one for each mark decorator

testing/test_mark.py

@@ -1302,3 +1302,45 @@ def test_staticmethod_wrapper_on_top(value: int):
     )
     result = pytester.runpytest()
     result.assert_outcomes(passed=8)
+
+
+def test_fixture_disallow_on_marked_functions() -> None:
+    """Test that applying @pytest.fixture to a marked function errors (#3364)."""
+    with pytest.raises(
+        pytest.fail.Exception,
+        match=r"Marks cannot be applied to fixtures",
+    ):
+
+        @pytest.fixture
+        @pytest.mark.parametrize("example", ["hello"])
+        @pytest.mark.usefixtures("tmp_path")
+        def foo():
+            raise NotImplementedError()
+
+
+def test_fixture_disallow_marks_on_fixtures() -> None:
+    """Test that applying a mark to a fixture errors (#3364)."""
+    with pytest.raises(
+        pytest.fail.Exception,
+        match=r"Marks cannot be applied to fixtures",
+    ):
+
+        @pytest.mark.parametrize("example", ["hello"])
+        @pytest.mark.usefixtures("tmp_path")
+        @pytest.fixture
+        def foo():
+            raise NotImplementedError()
+
+
+def test_fixture_disallowed_between_marks() -> None:
+    """Test that applying a mark to a fixture errors (#3364)."""
+    with pytest.raises(
+        pytest.fail.Exception,
+        match=r"Marks cannot be applied to fixtures",
+    ):
+
+        @pytest.mark.parametrize("example", ["hello"])
+        @pytest.fixture
+        @pytest.mark.usefixtures("tmp_path")
+        def foo():
+            raise NotImplementedError()