permit node to warn with any warning type, not just PytestWarning (#8052)

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

changelog/7615.improvement.rst

@@ -0,0 +1 @@
+:meth:`Node.warn <_pytest.nodes.Node.warn>` now permits any subclass of :class:`Warning`, not just :class:`PytestWarning <pytest.PytestWarning>`.

src/_pytest/nodes.py

@@ -34,7 +34,6 @@ from _pytest.store import Store
 if TYPE_CHECKING:
     # Imported here due to circular import.
     from _pytest.main import Session
-    from _pytest.warning_types import PytestWarning
     from _pytest._code.code import _TracebackStyle
 
 
@@ -198,27 +197,31 @@ class Node(metaclass=NodeMeta):
     def __repr__(self) -> str:
         return "<{} {}>".format(self.__class__.__name__, getattr(self, "name", None))
 
-    def warn(self, warning: "PytestWarning") -> None:
+    def warn(self, warning: Warning) -> None:
         """Issue a warning for this Node.
 
         Warnings will be displayed after the test session, unless explicitly suppressed.
 
         :param Warning warning:
-            The warning instance to issue. Must be a subclass of PytestWarning.
+            The warning instance to issue.
 
-        :raises ValueError: If ``warning`` instance is not a subclass of PytestWarning.
+        :raises ValueError: If ``warning`` instance is not a subclass of Warning.
 
         Example usage:
 
         .. code-block:: python
 
             node.warn(PytestWarning("some message"))
-        """
+            node.warn(UserWarning("some message"))
-        from _pytest.warning_types import PytestWarning
 
-        if not isinstance(warning, PytestWarning):
+        .. versionchanged:: 6.2
+            Any subclass of :class:`Warning` is now accepted, rather than only
+            :class:`PytestWarning <pytest.PytestWarning>` subclasses.
+        """
+        # enforce type checks here to avoid getting a generic type error later otherwise.
+        if not isinstance(warning, Warning):
             raise ValueError(
-                "warning must be an instance of PytestWarning or subclass, got {!r}".format(
+                "warning must be an instance of Warning or subclass, got {!r}".format(
                     warning
                 )
             )

testing/test_nodes.py

@@ -1,10 +1,12 @@
 from typing import List
+from typing import Type
 
 import py
 
 import pytest
 from _pytest import nodes
 from _pytest.pytester import Pytester
+from _pytest.warning_types import PytestWarning
 
 
 @pytest.mark.parametrize(
@@ -35,15 +37,33 @@ def test_node_from_parent_disallowed_arguments() -> None:
         nodes.Node.from_parent(None, config=None)  # type: ignore[arg-type]
 
 
-def test_std_warn_not_pytestwarning(pytester: Pytester) -> None:
+@pytest.mark.parametrize(
+    "warn_type, msg", [(DeprecationWarning, "deprecated"), (PytestWarning, "pytest")]
+)
+def test_node_warn_is_no_longer_only_pytest_warnings(
+    pytester: Pytester, warn_type: Type[Warning], msg: str
+) -> None:
     items = pytester.getitems(
         """
         def test():
             pass
     """
     )
-    with pytest.raises(ValueError, match=".*instance of PytestWarning.*"):
+    with pytest.warns(warn_type, match=msg):
-        items[0].warn(UserWarning("some warning"))  # type: ignore[arg-type]
+        items[0].warn(warn_type(msg))
+
+
+def test_node_warning_enforces_warning_types(pytester: Pytester) -> None:
+    items = pytester.getitems(
+        """
+        def test():
+            pass
+    """
+    )
+    with pytest.raises(
+        ValueError, match="warning must be an instance of Warning or subclass"
+    ):
+        items[0].warn(Exception("ok"))  # type: ignore[arg-type]
 
 
 def test__check_initialpaths_for_relpath() -> None: