Merge pull request #1433 from nicoddemus/issue-1427

Mention that pytest_addoption may be used from conftest files

fixes #1427

_pytest/hookspec.py

@@ -28,17 +28,14 @@ def pytest_plugin_registered(plugin, manager):
 
 @hookspec(historic=True)
 def pytest_addoption(parser):
-    """register argparse-style options and ini-style config values.
+    """register argparse-style options and ini-style config values,
+    called once at the beginning of a test run.
 
-    .. warning::
+    .. note::
 
-        This function must be implemented in a :ref:`plugin <pluginorder>`
-        and is called once at the beginning of a test run.
-
-        Implementing this hook from ``conftest.py`` files is **strongly**
-        discouraged because ``conftest.py`` files are lazily loaded and
-        may give strange *unknown option* errors depending on the directory
-        ``py.test`` is invoked from.
+        This function should be implemented only in plugins or ``conftest.py``
+        files situated at the tests root directory due to how py.test
+        :ref:`discovers plugins during startup <pluginorder>`.
 
     :arg parser: To add command line options, call
         :py:func:`parser.addoption(...) <_pytest.config.Parser.addoption>`.