Docs+Tests: clarify special discovery of pytest_generate_tests

changelog/13577.doc.rst

@@ -0,0 +1 @@
+Clarify that ``pytest_generate_tests`` is discovered in test modules/classes; other hooks must be in ``conftest.py`` or plugins.

doc/en/how-to/parametrize.rst

@@ -240,6 +240,13 @@ command line option and the parametrization of our test function:
         if "stringinput" in metafunc.fixturenames:
             metafunc.parametrize("stringinput", metafunc.config.getoption("stringinput"))
 
+.. note::
+
+    The :hook:`pytest_generate_tests` hook can also be implemented directly in a test
+    module or inside a test class; unlike other hooks, pytest will discover it there
+    as well. Other hooks must live in a :ref:`conftest.py <localplugin>` or a plugin.
+    See :ref:`writinghooks`.
+
 If we now pass two stringinput values, our test will run twice:
 
 .. code-block:: pytest

doc/en/how-to/writing_hook_functions.rst

@@ -235,6 +235,12 @@ Example:
         """
         print(config.hook)
 
+.. note::
+
+    Unlike other hooks, the :hook:`pytest_generate_tests` hook is also discovered when
+    defined inside a test module or test class. Other hooks must live in
+    :ref:`conftest.py plugins <localplugin>` or external plugins.
+    See :ref:`parametrize-basics` and the :ref:`hook-reference`.
 
 .. _`addoptionhooks`: