Add support for .pytest.ini as an alternative to pytest.ini

Closes #9987

AUTHORS

@@ -67,6 +67,7 @@ Cheuk Ting Ho
 Chris Lamb
 Chris NeJame
 Chris Rose
+Chris Wheeler
 Christian Boelsen
 Christian Fetzer
 Christian Neumüller

changelog/9987.improvement.rst

@@ -0,0 +1 @@
+Added support for hidden configuration file by allowing ``.pytest.ini`` as an alternative to ``pytest.ini``.

doc/en/reference/customize.rst

@@ -29,9 +29,11 @@ pytest.ini
 
 ``pytest.ini`` files take precedence over other files, even when empty.
 
+Alternatively, the hidden version ``.pytest.ini`` can be used.
+
 .. code-block:: ini
 
-    # pytest.ini
+    # pytest.ini or .pytest.ini
     [pytest]
     minversion = 6.0
     addopts = -ra -q

doc/en/reference/reference.rst

@@ -1154,9 +1154,10 @@ Consult the :ref:`internal-warnings` section in the documentation for more infor
 Configuration Options
 ---------------------
 
-Here is a list of builtin configuration options that may be written in a ``pytest.ini``, ``pyproject.toml``, ``tox.ini`` or ``setup.cfg``
-file, usually located at the root of your repository. To see each file format in details, see
-:ref:`config file formats`.
+Here is a list of builtin configuration options that may be written in a ``pytest.ini`` (or ``.pytest.ini``),
+``pyproject.toml``, ``tox.ini``, or ``setup.cfg`` file, usually located at the root of your repository.
+
+To see each file format in details, see :ref:`config file formats`.
 
 .. warning::
     Usage of ``setup.cfg`` is not recommended except for very simple use cases. ``.cfg``

src/_pytest/config/findpaths.py

@@ -96,6 +96,7 @@ def locate_config(
     and return a tuple of (rootdir, inifile, cfg-dict)."""
     config_names = [
         "pytest.ini",
+        ".pytest.ini",
         "pyproject.toml",
         "tox.ini",
         "setup.cfg",

testing/test_config.py

@@ -112,21 +112,26 @@ class TestParseIni:
 
     @pytest.mark.parametrize(
         "section, name",
-        [("tool:pytest", "setup.cfg"), ("pytest", "tox.ini"), ("pytest", "pytest.ini")],
+        [
+            ("tool:pytest", "setup.cfg"),
+            ("pytest", "tox.ini"),
+            ("pytest", "pytest.ini"),
+            ("pytest", ".pytest.ini"),
+        ],
     )
     def test_ini_names(self, pytester: Pytester, name, section) -> None:
         pytester.path.joinpath(name).write_text(
             textwrap.dedent(
                 """
             [{section}]
-            minversion = 1.0
+            minversion = 3.36
         """.format(
                     section=section
                 )
             )
         )
         config = pytester.parseconfig()
-        assert config.getini("minversion") == "1.0"
+        assert config.getini("minversion") == "3.36"
 
     def test_pyproject_toml(self, pytester: Pytester) -> None:
         pytester.makepyprojecttoml(