Support using flag --skipslow instead of -m "not slow" for pytest

[mhucka]

The flag -m "not slow" was not only annoying to type: it invited misspelling and waste of time.

This PR changes the flag to be --skipslow, following the same thing done in the ReCirq project.

[gemini-code-assist]

Code Review

This pull request introduces a new --skipslow flag for pytest to improve test execution control, updating the CONTRIBUTING.md documentation, pyproject.toml configuration, and conftest.py setup. The reviewer recommended using more specific type hints (pytest.Parser and pytest.Item) and the getoption API instead of getvalue for better type safety and correctness.

[gemini-code-assist]

Code Review

This pull request introduces a custom --skipslow command-line option for pytest to skip slow tests, replacing the previous -m "not slow" marker-based filtering. It updates the documentation, pytest configuration, and adds unit tests for the new conftest hooks. The review feedback points out that checking item.keywords for "slow" is a pytest anti-pattern because it can match test names or module names containing the word "slow", and suggests using item.get_closest_marker("slow") instead, along with updating the corresponding unit tests to mock this method.

[gemini-code-assist]

Using "slow" in item.keywords is a pytest anti-pattern. item.keywords contains not only the markers applied to a test, but also the names of the test function, class, and module (and their components split by underscores). This means any test with the word slow in its name, class, or file name (e.g., test_slow_algorithm) will be incorrectly skipped when --skipslow is passed, even if it is not marked with @pytest.mark.slow.

Instead, use item.get_closest_marker("slow") to safely and precisely check for the presence of the marker.

Suggested change

	def pytest_runtest_setup(item: pytest.Item) -> None:
	if "slow" in item.keywords and item.config.getoption("skipslow"):
	pytest.skip("skipped because of --skipslow option")
	def pytest_runtest_setup(item: pytest.Item) -> None:
	if item.get_closest_marker("slow") is not None and item.config.getoption("skipslow"):
	pytest.skip("skipped because of --skipslow option")

[gemini-code-assist]

Since we are updating pytest_runtest_setup to use item.get_closest_marker("slow") instead of checking item.keywords, we should update the unit tests to mock get_closest_marker accordingly.

    def test_pytest_runtest_setup_skips(self):
        import conftest
        import pytest
        from unittest.mock import MagicMock

        # Create mock item representing a slow test when skipslow is True.
        item = MagicMock()
        item.get_closest_marker.return_value = MagicMock()
        item.config.getoption.return_value = True

        with self.assertRaises(pytest.skip.Exception):
            conftest.pytest_runtest_setup(item)

        item.get_closest_marker.assert_called_once_with("slow")
        item.config.getoption.assert_called_once_with("skipslow")

    def test_pytest_runtest_setup_does_not_skip_if_not_slow(self):
        import conftest
        from unittest.mock import MagicMock

        # Test case 1: Not marked as 'slow', skipslow is True.
        item = MagicMock()
        item.get_closest_marker.return_value = None
        item.config.getoption.return_value = True

        # Should not raise an exception.
        conftest.pytest_runtest_setup(item)

        # Test case 2: Marked as 'slow', skipslow is False.
        item = MagicMock()
        item.get_closest_marker.return_value = MagicMock()
        item.config.getoption.return_value = False

        conftest.pytest_runtest_setup(item)