Use False, instead of None as default for _XfailMarkDecorator's condition param and update doc

AUTHORS

@@ -339,6 +339,7 @@ Saiprasad Kale
 Samuel Colvin
 Samuel Dion-Girardeau
 Samuel Searles-Bryant
+Samuel Therrien (Avasam)
 Samuele Pedroni
 Sanket Duthade
 Sankt Petersbug

changelog/11600.improvement.rst

@@ -0,0 +1 @@
+Improved the documentation and type signature for :func:`pytest.mark.xfail <pytest.mark.xfail>`'s ``condition`` param to use ``False`` as the default value.

doc/en/reference/reference.rst

@@ -239,12 +239,11 @@ pytest.mark.xfail
 
 Marks a test function as *expected to fail*.
 
-.. py:function:: pytest.mark.xfail(condition=None, *, reason=None, raises=None, run=True, strict=xfail_strict)
+.. py:function:: pytest.mark.xfail(condition=False, *, reason=None, raises=None, run=True, strict=xfail_strict)
 
-    :type condition: bool or str
-    :param condition:
+    :keyword Union[bool, str] condition:
         Condition for marking the test function as xfail (``True/False`` or a
-        :ref:`condition string <string conditions>`). If a bool, you also have
+        :ref:`condition string <string conditions>`). If a ``bool``, you also have
         to specify ``reason`` (see :ref:`condition string <string conditions>`).
     :keyword str reason:
         Reason why the test function is marked as xfail.

src/_pytest/mark/structures.py

@@ -457,7 +457,7 @@ def __call__(self, arg: Markable) -> Markable:
         @overload
         def __call__(
             self,
-            condition: Union[str, bool] = ...,
+            condition: Union[str, bool] = False,
             *conditions: Union[str, bool],
             reason: str = ...,
             run: bool = ...,