Trac #31003: Add minimal pytest configuration

Add a minimal pytest configuration, so that calling `pytest` from `src`
passes without any errors (and without finding any tests for the
moment).

This is a preparation for future usages of pytest, such as #30362 or
#30738, and is in the general spirit of #28936 (since pytest is perhaps
''the'' testing framework for python). For example, one could imagine
using `pytest doctest_modules` to run all sage doctests as well.

URL: https://trac.sagemath.org/31003
Reported by: gh-tobiasdiez
Ticket author(s): Tobias Diez
Reviewer(s): Matthias Koeppe

Author: Release Manager

src/conftest.py

@@ -0,0 +1,31 @@
+# pyright: strict
+
+"""Configuration and fixtures for pytest.
+
+This file configures pytest and provides some global fixtures.
+See https://docs.pytest.org/en/latest/index.html for more details.
+
+At the moment, Sage is not yet using any tests based on pytest.
+"""
+
+from __future__ import annotations
+from typing import Any
+import pytest
+
+# Ignore a few test files that are (not yet) using pytest
+collect_ignore = [
+    "sage/misc/nested_class_test.py",
+    "sage/repl/rich_output/backend_test.py",
+    "sage/tests/deprecation_test.py"
+]
+
+
+@pytest.fixture(autouse=True)
+def add_imports(doctest_namespace: dict[str, Any]):
+    """
+    Add global imports for doctests.
+
+    See `pytest documentation <https://docs.pytest.org/en/stable/doctest.html#doctest-namespace-fixture>`.
+    """
+    import sage.all  # type: ignore # implicitly used below by calling locals()
+    doctest_namespace.update(**locals())

src/doc/en/developer/tools.rst

@@ -8,14 +8,26 @@
 Additional development and testing tools
 ========================================
 
+Pytest
+===============================
+`Pytest <https://docs.pytest.org/en/stable/>`_ is a testing framework.
+At the moment, Sage is not yet using any tests based on pytest.
+
+*Installation:* ``pip install -U pytest``, see `documentation <https://docs.pytest.org/en/stable/getting-started.html#installation-and-getting-started>`__ for details.
+*Usage:*
+- Manual: Run ``pytest path/to/the/test_file.py`` or ``pytest`` to run all tests (from a virtual environment with Sage installed)
+- VS Code: Install the `Python <https://marketplace.visualstudio.com/items?itemName=ms-python.python>`_ extension and follow the `offical VS Code documentation <https://code.visualstudio.com/docs/python/testing>`__.
+*Configuration:* ``conftest.py`` in the source folder
+*Documentation:* https://docs.pytest.org/en/stable/index.html
+
 Pyright 
 ===============================
-`Pyright <https://github.com/microsoft/pyright>` is static type checker.
+`Pyright <https://github.com/microsoft/pyright>`_ is static type checker.
 
-*Installation:* ``npm install -g pyright``, see `documentation <https://github.com/microsoft/pyright#installation>`_ for details.
+*Installation:* ``npm install -g pyright``, see `documentation <https://github.com/microsoft/pyright#installation>`__ for details.
 *Usage:*
 - Manual: Run ``pyright path/to/the/file.py``
-- VS Code: Install the `Pylance <https://marketplace.visualstudio.com/items?itemName=ms-python.vscode-pylance>`_ extension.
+- VS Code: Install the `Pylance <https://marketplace.visualstudio.com/items?itemName=ms-python.vscode-pylance>`__ extension.
 *Configuration:* ``pyrightconfig.json`` in the root
 *Note*: Currently, only the manifolds package is checked. Further packages can be added in the ``pyrightconfig.json`` file.
 *Documentation:* https://github.com/microsoft/pyright#documentation
@@ -27,7 +39,7 @@ Pycodestyle
 *Installation:* ``pip install -U pycodestyle --user``
 *Usage:*
 - Manual: Run ``pycodestyle path/to/the/file.py``
-- VS Code: Activate by adding the setting ``"python.linting.pycodestyleEnabled": true``, see `official VS Code documentation <https://code.visualstudio.com/docs/python/linting>`_ for details.
+- VS Code: Activate by adding the setting ``"python.linting.pycodestyleEnabled": true``, see `official VS Code documentation <https://code.visualstudio.com/docs/python/linting>`__ for details.
 *Configuration:* ``[pycodestyle]`` block in ``src/tox.ini``
 *Documentation:* https://pycodestyle.pycqa.org/en/latest/index.html
 

src/tox.ini

@@ -115,3 +115,6 @@ commands = codespell \
     --dictionary={toxinidir}/.codespell-dictionary.txt \
     --ignore-words={toxinidir}/.codespell-ignore.txt \
     {posargs:{toxinidir}/sage/}
+
+[pytest]
+python_files = *_test.py