tests(regressions): Add autouse fixtures regression test (#56)

Backport: pytest commit 9cd14b4ff (2024-02-06)
Ref: pytest-dev/pytest@9cd14b4ff

what:
- Test autouse fixtures from conftest.py with .rst/.md doctests
- Parametrized over scopes: module, session, class, function
- Parametrized over file types: .rst, .md (8 test cases total)

Refs: pytest-dev/pytest#11929

Author: tony

tests/regressions/test_autouse_fixtures.py

@@ -0,0 +1,136 @@
+"""Regression test for autouse fixtures with doctest files.
+
+Backported from pytest commit 9cd14b4ff (2024-02-06).
+https://github.com/pytest-dev/pytest/commit/9cd14b4ff
+
+The original pytest test verified autouse fixtures defined in the same .py module
+as the doctest get picked up properly. For gp-libs, DocTestDocutilsFile handles
+.rst/.md files where fixtures can only come from conftest.py (not from the
+document itself).
+
+This test verifies that autouse fixtures from conftest.py are properly discovered
+for .rst and .md doctest files across different fixture scopes.
+
+Refs: pytest-dev/pytest#11929
+"""
+
+from __future__ import annotations
+
+import textwrap
+import typing as t
+
+import _pytest.pytester
+import pytest
+
+
+class AutouseFixtureTestCase(t.NamedTuple):
+    """Test fixture for autouse fixtures with doctest files."""
+
+    test_id: str
+    scope: str
+    file_ext: str
+    file_content: str
+
+
+RST_DOCTEST_CONTENT = textwrap.dedent(
+    """
+Example
+=======
+
+.. doctest::
+
+   >>> get_value()
+   'fixture ran'
+    """,
+)
+
+MD_DOCTEST_CONTENT = textwrap.dedent(
+    """
+# Example
+
+```{doctest}
+>>> get_value()
+'fixture ran'
+```
+    """,
+)
+
+SCOPES = ["module", "session", "class", "function"]
+
+FIXTURES = [
+    AutouseFixtureTestCase(
+        test_id=f"{scope}-rst",
+        scope=scope,
+        file_ext=".rst",
+        file_content=RST_DOCTEST_CONTENT,
+    )
+    for scope in SCOPES
+] + [
+    AutouseFixtureTestCase(
+        test_id=f"{scope}-md",
+        scope=scope,
+        file_ext=".md",
+        file_content=MD_DOCTEST_CONTENT,
+    )
+    for scope in SCOPES
+]
+
+
+@pytest.mark.parametrize(
+    AutouseFixtureTestCase._fields,
+    FIXTURES,
+    ids=[f.test_id for f in FIXTURES],
+)
+def test_autouse_fixtures_with_doctest_files(
+    pytester: _pytest.pytester.Pytester,
+    test_id: str,
+    scope: str,
+    file_ext: str,
+    file_content: str,
+) -> None:
+    """Autouse fixtures from conftest.py work with .rst/.md doctest files.
+
+    Regression test for pytest-dev/pytest#11929.
+    Backported from pytest commit 9cd14b4ff (2024-02-06).
+    """
+    pytester.plugins = ["pytest_doctest_docutils"]
+    pytester.makefile(
+        ".ini",
+        pytest=textwrap.dedent(
+            """
+[pytest]
+addopts=-p no:doctest -vv
+            """.strip(),
+        ),
+    )
+
+    # Create conftest with autouse fixture that sets a global value
+    pytester.makeconftest(
+        textwrap.dedent(
+            f"""
+import pytest
+
+VALUE = "fixture did not run"
+
+@pytest.fixture(autouse=True, scope="{scope}")
+def set_value():
+    global VALUE
+    VALUE = "fixture ran"
+
+@pytest.fixture(autouse=True)
+def add_get_value_to_doctest_namespace(doctest_namespace):
+    def get_value():
+        return VALUE
+    doctest_namespace["get_value"] = get_value
+            """,
+        ),
+    )
+
+    # Create the doctest file
+    tests_path = pytester.path / "tests"
+    tests_path.mkdir()
+    test_file = tests_path / f"example{file_ext}"
+    test_file.write_text(file_content, encoding="utf-8")
+
+    result = pytester.runpytest(str(test_file))
+    result.assert_outcomes(passed=1)