hookspec: document conftest behavior for all hooks (#9496)

Have each hook explain how implementing it in conftests works. This is part of the functional specification of a hook.

src/_pytest/hookspec.py

@@ -58,6 +58,12 @@ def pytest_addhooks(pluginmanager: "PytestPluginManager") -> None:
 
     .. note::
         This hook is incompatible with hook wrappers.
+
+    Use in conftest plugins
+    =======================
+
+    If a conftest plugin implements this hook, it will be called immediately
+    when the conftest is registered.
     """
 
 
@@ -75,6 +81,14 @@ def pytest_plugin_registered(
 
     .. note::
         This hook is incompatible with hook wrappers.
+
+    Use in conftest plugins
+    =======================
+
+    If a conftest plugin implements this hook, it will be called immediately
+    when the conftest is registered, once for each plugin registered thus far
+    (including itself!), and for all plugins thereafter when they are
+    registered.
     """
 
 
@@ -83,12 +97,6 @@ def pytest_addoption(parser: "Parser", pluginmanager: "PytestPluginManager") ->
     """Register argparse-style options and ini-style config values,
     called once at the beginning of a test run.
 
-    .. note::
-
-        This function should be implemented only in plugins or ``conftest.py``
-        files situated at the tests root directory due to how pytest
-        :ref:`discovers plugins during startup <pluginorder>`.
-
     :param parser:
         To add command line options, call
         :py:func:`parser.addoption(...) <pytest.Parser.addoption>`.
@@ -114,6 +122,14 @@ def pytest_addoption(parser: "Parser", pluginmanager: "PytestPluginManager") ->
 
     .. note::
         This hook is incompatible with hook wrappers.
+
+    Use in conftest plugins
+    =======================
+
+    If a conftest plugin implements this hook, it will be called immediately
+    when the conftest is registered.
+
+    This hook is only called for :ref:`initial conftests <pluginorder>`.
     """
 
 
@@ -121,16 +137,17 @@ def pytest_addoption(parser: "Parser", pluginmanager: "PytestPluginManager") ->
 def pytest_configure(config: "Config") -> None:
     """Allow plugins and conftest files to perform initial configuration.
 
-    This hook is called for every plugin and initial conftest file
-    after command line options have been parsed.
-
-    After that, the hook is called for other conftest files as they are
-    imported.
-
     .. note::
         This hook is incompatible with hook wrappers.
 
     :param config: The pytest config object.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is called for every :ref:`initial conftest <pluginorder>` file
+    after command line options have been parsed. After that, the hook is called
+    for other conftest files as they are registered.
     """
 
 
@@ -149,28 +166,35 @@ def pytest_cmdline_parse(
     Stops at first non-None result, see :ref:`firstresult`.
 
     .. note::
-        This hook will only be called for plugin classes passed to the
+        This hook is only called for plugin classes passed to the
         ``plugins`` arg when using `pytest.main`_ to perform an in-process
         test run.
 
     :param pluginmanager: The pytest plugin manager.
     :param args: List of arguments passed on the command line.
     :returns: A pytest config object.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is not called for conftest files.
     """
 
 
 def pytest_load_initial_conftests(
     early_config: "Config", parser: "Parser", args: List[str]
 ) -> None:
-    """Called to implement the loading of initial conftest files ahead
-    of command line option parsing.
-
-    .. note::
-        This hook will not be called for ``conftest.py`` files, only for setuptools plugins.
+    """Called to implement the loading of :ref:`initial conftest files
+    <pluginorder>` ahead of command line option parsing.
 
     :param early_config: The pytest config object.
     :param args: Arguments passed on the command line.
     :param parser: To add command line options.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is not called for conftest files.
     """
 
 
@@ -185,6 +209,11 @@ def pytest_cmdline_main(config: "Config") -> Optional[Union["ExitCode", int]]:
 
     :param config: The pytest config object.
     :returns: The exit code.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is only called for :ref:`initial conftests <pluginorder>`.
     """
 
 
@@ -227,6 +256,11 @@ def pytest_collection(session: "Session") -> Optional[object]:
     counter (and returns `None`).
 
     :param session: The pytest session object.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is only called for :ref:`initial conftests <pluginorder>`.
     """
 
 
@@ -239,6 +273,11 @@ def pytest_collection_modifyitems(
     :param session: The pytest session object.
     :param config: The pytest config object.
     :param items: List of item objects.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -246,6 +285,11 @@ def pytest_collection_finish(session: "Session") -> None:
     """Called after collection has been performed and modified.
 
     :param session: The pytest session object.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -268,6 +312,14 @@ def pytest_ignore_collect(collection_path: Path, config: "Config") -> Optional[b
 
     .. versionchanged:: 8.0.0
         The ``path`` parameter has been removed.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collection path, only
+    conftest files in parent directories of the collection path are consulted
+    (if the path is a directory, its own conftest file is *not* consulted - a
+    directory cannot ignore itself!).
     """
 
 
@@ -289,6 +341,14 @@ def pytest_collect_directory(path: Path, parent: "Collector") -> "Optional[Colle
 
     See :ref:`custom directory collectors` for a simple example of use of this
     hook.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collection path, only
+    conftest files in parent directories of the collection path are consulted
+    (if the path is a directory, its own conftest file is *not* consulted - a
+    directory cannot collect itself!).
     """
 
 
@@ -309,6 +369,12 @@ def pytest_collect_file(file_path: Path, parent: "Collector") -> "Optional[Colle
 
     .. versionchanged:: 8.0.0
         The ``path`` parameter was removed.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given file path, only
+    conftest files in parent directories of the file path are consulted.
     """
 
 
@@ -320,6 +386,13 @@ def pytest_collectstart(collector: "Collector") -> None:
 
     :param collector:
         The collector.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collector, only
+    conftest files in the collector's directory and its parent directories are
+    consulted.
     """
 
 
@@ -328,6 +401,12 @@ def pytest_itemcollected(item: "Item") -> None:
 
     :param item:
         The item.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -336,6 +415,13 @@ def pytest_collectreport(report: "CollectReport") -> None:
 
     :param report:
         The collect report.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collector, only
+    conftest files in the collector's directory and its parent directories are
+    consulted.
     """
 
 
@@ -346,6 +432,11 @@ def pytest_deselected(items: Sequence["Item"]) -> None:
 
     :param items:
         The items.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -358,6 +449,13 @@ def pytest_make_collect_report(collector: "Collector") -> "Optional[CollectRepor
 
     :param collector:
         The collector.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collector, only
+    conftest files in the collector's directory and its parent directories are
+    consulted.
     """
 
 
@@ -385,6 +483,13 @@ def pytest_pycollect_makemodule(module_path: Path, parent) -> Optional["Module"]
 
     .. versionchanged:: 8.0.0
         The ``path`` parameter has been removed in favor of ``module_path``.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given parent collector,
+    only conftest files in the collector's directory and its parent directories
+    are consulted.
     """
 
 
@@ -404,6 +509,13 @@ def pytest_pycollect_makeitem(
         The object.
     :returns:
         The created items/collectors.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given collector, only
+    conftest files in the collector's directory and its parent directories
+    are consulted.
     """
 
 
@@ -415,6 +527,13 @@ def pytest_pyfunc_call(pyfuncitem: "Function") -> Optional[object]:
 
     :param pyfuncitem:
         The function item.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only
+    conftest files in the item's directory and its parent directories
+    are consulted.
     """
 
 
@@ -423,6 +542,13 @@ def pytest_generate_tests(metafunc: "Metafunc") -> None:
 
     :param metafunc:
         The :class:`~pytest.Metafunc` helper for the test function.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given function definition,
+    only conftest files in the functions's directory and its parent directories
+    are consulted.
     """
 
 
@@ -441,6 +567,11 @@ def pytest_make_parametrize_id(
     :param config: The pytest config object.
     :param val: The parametrized value.
     :param argname: The automatic parameter name produced by pytest.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -467,6 +598,11 @@ def pytest_runtestloop(session: "Session") -> Optional[object]:
 
     Stops at first non-None result, see :ref:`firstresult`.
     The return value is not used, but only stops further processing.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -505,6 +641,11 @@ def pytest_runtest_protocol(
 
     Stops at first non-None result, see :ref:`firstresult`.
     The return value is not used, but only stops further processing.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -519,6 +660,12 @@ def pytest_runtest_logstart(
     :param location: A tuple of ``(filename, lineno, testname)``
         where ``filename`` is a file path relative to ``config.rootpath``
         and ``lineno`` is 0-based.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -533,6 +680,12 @@ def pytest_runtest_logfinish(
     :param location: A tuple of ``(filename, lineno, testname)``
         where ``filename`` is a file path relative to ``config.rootpath``
         and ``lineno`` is 0-based.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -546,6 +699,12 @@ def pytest_runtest_setup(item: "Item") -> None:
 
     :param item:
         The item.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -556,6 +715,12 @@ def pytest_runtest_call(item: "Item") -> None:
 
     :param item:
         The item.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -574,6 +739,12 @@ def pytest_runtest_teardown(item: "Item", nextitem: Optional["Item"]) -> None:
         scheduled). This argument is used to perform exact teardowns, i.e.
         calling just enough finalizers so that nextitem only needs to call
         setup functions.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -590,6 +761,12 @@ def pytest_runtest_makereport(
     :param call: The :class:`~pytest.CallInfo` for the phase.
 
     Stops at first non-None result, see :ref:`firstresult`.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -598,6 +775,12 @@ def pytest_runtest_logreport(report: "TestReport") -> None:
     of the setup, call and teardown runtest phases of an item.
 
     See :hook:`pytest_runtest_protocol` for a description of the runtest protocol.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -611,6 +794,12 @@ def pytest_report_to_serializable(
 
     :param config: The pytest config object.
     :param report: The report.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. The exact details may depend
+    on the plugin which calls the hook.
     """
 
 
@@ -623,6 +812,12 @@ def pytest_report_from_serializable(
     :hook:`pytest_report_to_serializable`.
 
     :param config: The pytest config object.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. The exact details may depend
+    on the plugin which calls the hook.
     """
 
 
@@ -650,6 +845,13 @@ def pytest_fixture_setup(
         If the fixture function returns None, other implementations of
         this hook function will continue to be called, according to the
         behavior of the :ref:`firstresult` option.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given fixture, only
+    conftest files in the fixture scope's directory and its parent directories
+    are consulted.
     """
 
 
@@ -664,6 +866,13 @@ def pytest_fixture_post_finalizer(
         The fixture definition object.
     :param request:
         The fixture request object.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given fixture, only
+    conftest files in the fixture scope's directory and its parent directories
+    are consulted.
     """
 
 
@@ -677,6 +886,11 @@ def pytest_sessionstart(session: "Session") -> None:
     and entering the run test loop.
 
     :param session: The pytest session object.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is only called for :ref:`initial conftests <pluginorder>`.
     """
 
 
@@ -688,6 +902,11 @@ def pytest_sessionfinish(
 
     :param session: The pytest session object.
     :param exitstatus: The status which pytest will return to the system.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -695,6 +914,11 @@ def pytest_unconfigure(config: "Config") -> None:
     """Called before test process is exited.
 
     :param config: The pytest config object.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook.
     """
 
 
@@ -717,6 +941,12 @@ def pytest_assertrepr_compare(
     :param op: The operator, e.g. `"=="`, `"!="`, `"not in"`.
     :param left: The left operand.
     :param right: The right operand.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -745,6 +975,12 @@ def pytest_assertion_pass(item: "Item", lineno: int, orig: str, expl: str) -> No
     :param lineno: Line number of the assert statement.
     :param orig: String with the original assertion.
     :param expl: String with the assert explanation.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in the item's directory and its parent directories are consulted.
     """
 
 
@@ -769,18 +1005,17 @@ def pytest_report_header(  # type:ignore[empty-body]
         If you want to have your line(s) displayed first, use
         :ref:`trylast=True <plugin-hookorder>`.
 
-    .. note::
-
-        This function should be implemented only in plugins or ``conftest.py``
-        files situated at the tests root directory due to how pytest
-        :ref:`discovers plugins during startup <pluginorder>`.
-
     .. versionchanged:: 7.0.0
         The ``start_path`` parameter was added as a :class:`pathlib.Path`
         equivalent of the ``startdir`` parameter.
 
     .. versionchanged:: 8.0.0
         The ``startdir`` parameter has been removed.
+
+    Use in conftest plugins
+    =======================
+
+    This hook is only called for :ref:`initial conftests <pluginorder>`.
     """
 
 
@@ -814,6 +1049,11 @@ def pytest_report_collectionfinish(  # type:ignore[empty-body]
 
     .. versionchanged:: 8.0.0
         The ``startdir`` parameter has been removed.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -842,6 +1082,11 @@ def pytest_report_teststatus(  # type:ignore[empty-body]
     :returns: The test status.
 
     Stops at first non-None result, see :ref:`firstresult`.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -858,6 +1103,11 @@ def pytest_terminal_summary(
 
     .. versionadded:: 4.2
         The ``config`` parameter.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -882,7 +1132,8 @@ def pytest_warning_recorded(
         * ``"runtest"``: during test execution.
 
     :param nodeid:
-        Full id of the item.
+        Full id of the item. Empty string for warnings that are not specific to
+        a particular node.
 
     :param location:
         When available, holds information about the execution context of the captured
@@ -890,6 +1141,13 @@ def pytest_warning_recorded(
         when the execution context is at the module level.
 
     .. versionadded:: 6.0
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. If the warning is specific to a
+    particular node, only conftest files in parent directories of the node are
+    consulted.
     """
 
 
@@ -913,6 +1171,12 @@ def pytest_markeval_namespace(  # type:ignore[empty-body]
 
     :param config: The pytest config object.
     :returns: A dictionary of additional globals to add.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given item, only conftest
+    files in parent directories of the item are consulted.
     """
 
 
@@ -932,6 +1196,11 @@ def pytest_internalerror(
 
     :param excrepr: The exception repr object.
     :param excinfo: The exception info.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -941,6 +1210,11 @@ def pytest_keyboard_interrupt(
     """Called for keyboard interrupt.
 
     :param excinfo: The exception info.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -967,6 +1241,12 @@ def pytest_exception_interact(
         The call information. Contains the exception.
     :param report:
         The collection or test report.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest file can implement this hook. For a given node, only conftest
+    files in parent directories of the node are consulted.
     """
 
 
@@ -978,6 +1258,11 @@ def pytest_enter_pdb(config: "Config", pdb: "pdb.Pdb") -> None:
 
     :param config: The pytest config object.
     :param pdb: The Pdb instance.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """
 
 
@@ -989,4 +1274,9 @@ def pytest_leave_pdb(config: "Config", pdb: "pdb.Pdb") -> None:
 
     :param config: The pytest config object.
     :param pdb: The Pdb instance.
+
+    Use in conftest plugins
+    =======================
+
+    Any conftest plugin can implement this hook.
     """