Deprecate RaisesGroup

src/trio/testing/_raises_group.py

@@ -15,6 +15,8 @@
 
 from trio._util import final
 
+from .._deprecate import warn_deprecated
+
 if TYPE_CHECKING:
     import builtins
 
@@ -531,6 +533,13 @@ def __init__(
             | None
         ) = None,
     ):
+        warn_deprecated(
+            "RaisesGroup",
+            version="0.31.0",
+            issue=3326,
+            instead="See https://docs.pytest.org/en/stable/reference/reference.html#pytest.RaisesGroup",
+            use_triodeprecationwarning=True,
+        )
         # The type hint on the `self` and `check` parameters uses different formats
         # that are *very* hard to reconcile while adhering to the overloads, so we cast
         # it to avoid an error when passing it to super().__init__