docs: clarify capture fixture precedence over -s

changelog/13731.doc.rst

@@ -0,0 +1 @@
+Clarified that capture fixtures (e.g. ``capsys`` and ``capfd``) take precedence over the ``-s`` / ``--capture=no`` command-line options in :ref:`Accessing captured output from a test function <accessing-captured-output>`.

doc/en/how-to/capture-stdout-stderr.rst

@@ -109,6 +109,8 @@ of the failing function and hide the other one:
     FAILED test_module.py::test_func2 - assert False
     ======================= 1 failed, 1 passed in 0.12s ========================
 
+.. _accessing-captured-output:
+
 Accessing captured output from a test function
 ---------------------------------------------------
 
@@ -129,6 +131,17 @@ Here is an example test function that performs some output related checks:
         captured = capsys.readouterr()
         assert captured.out == "next\n"
 
+
+.. note::
+
+   When a capture fixture such as :fixture:`capsys` or :fixture:`capfd` is used,
+   it takes precedence over the global capturing configuration set via
+   command-line options such as ``-s`` or ``--capture=no``.
+
+   This means that output produced within a test using a capture fixture will
+   still be captured and available via ``readouterr()``, even if global capturing
+   is disabled.
+
 The ``readouterr()`` call snapshots the output so far -
 and capturing will be continued.  After the test
 function finishes the original streams will