build(conftest): Move to root level

Required by pytest_plugins to be at the top level, makes

    py.test README.md

possible to run, as well as keeping conftest.py excluded from wheel
package.

Author: tony

conftest.py

@@ -0,0 +1,41 @@
+"""Conftest.py (root-level)
+
+We keep this in root pytest fixtures in pytest's doctest plugin to be available, as well
+as avoiding conftest.py from being included in the wheel, in addition to pytest_plugin
+for pytester only being available via the root directory.
+
+See "pytest_plugins in non-top-level conftest files" in
+https://docs.pytest.org/en/stable/deprecations.html
+"""
+import pathlib
+import typing as t
+
+import pytest
+
+pytest_plugins = ["pytester"]
+
+
+@pytest.fixture(autouse=True)
+def add_doctest_fixtures(
+    request: pytest.FixtureRequest,
+    doctest_namespace: t.Dict[str, t.Any],
+) -> None:
+    from _pytest.doctest import DoctestItem
+
+    if isinstance(request._pyfuncitem, DoctestItem):
+        request.getfixturevalue("add_doctest_fixtures")
+        request.getfixturevalue("set_home")
+
+
+@pytest.fixture(autouse=True)
+def setup(
+    request: pytest.FixtureRequest,
+    gitconfig: pathlib.Path,
+    set_home: pathlib.Path,
+) -> None:
+    pass
+
+
+@pytest.fixture(autouse=True)
+def cwd_default(monkeypatch: pytest.MonkeyPatch, tmp_path: pathlib.Path) -> None:
+    monkeypatch.chdir(tmp_path)

pyproject.toml

@@ -50,6 +50,7 @@ packages = [
 ]
 include = [
   { path = "tests", format = "sdist" },
+  { path = "conftest.py", format = "sdist" },
 ]
 
 [tool.poetry.urls]