Merge remote-tracking branch 'graingert/warn-when-a-mark-is-applied-to-a-fixture' into warn-when-a-mark-is-applied-to-a-fixture

changelog/3664.deprecation.rst

@@ -1 +1,3 @@
-Applying a mark to a fixture function is deprecated. Doing so has no effect.
+Applying a mark to a fixture function now issues a warning: marks in fixtures never had any effect, but it is a common user error to apply a mark to a fixture (for example ``usefixtures``) and expect it to work.
+
+This will become an error in the future.

doc/en/deprecations.rst

@@ -278,7 +278,17 @@ Applying a mark to a fixture function
 
 .. deprecated:: 7.2
 
-Applying a mark to a fixture function is deprecated. Doing so has no effect, and will raise an error in the next version.
+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.
 
 
 Backward compatibilities in ``Parser.addoption``

src/_pytest/deprecated.py

@@ -107,7 +107,10 @@ HOOK_LEGACY_MARKING = UnformattedWarning(
     "#configuring-hook-specs-impls-using-markers",
 )
 
-MARKED_FIXTURE = PytestDeprecationWarning("Marks applied to fixtures have no effect")
+MARKED_FIXTURE = PytestDeprecationWarning(
+    "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"
+)
 
 # You want to make some `__init__` or function "private".
 #