cursor,windsurf(rules): Add pytest testing guidelines to project rules

why: Standardize pytest testing practices across the project.
what:
- Add section specifying use of fixtures over mocks
- Example: libtmux-specific fixtures (server, session, window, pane)
- Require documentation for exceptional test cases
- Recommend tmp_path fixture over tempfile
- Prefer monkeypatch fixture over unittest.mock

refs: Improves consistency and maintainability of test suite

Author: tony

.cursor/rules/dev-loop.mdc

@@ -156,3 +156,14 @@ For doctests in `src/**/*.py` files:
    # Watch specific modules for doctest changes
    uv run ptw . --now --doctest-modules src/path/to/module.py
    ```
+
+### Pytest Testing Guidelines
+
+1. **Use existing fixtures over mocks**:
+   - Use fixtures from conftest.py instead of `monkeypatch` and `MagicMock` when available
+   - For instance, if using libtmux, use provided fixtures: `server`, `session`, `window`, and `pane`
+   - Document in test docstrings why standard fixtures weren't used for exceptional cases
+
+2. **Preferred pytest patterns**:
+   - Use `tmp_path` (pathlib.Path) fixture over Python's `tempfile`
+   - Use `monkeypatch` fixture over `unittest.mock`

.windsurfrules

@@ -111,3 +111,11 @@
   - Separate subject from body with a blank line
   - Mark breaking changes clearly: `BREAKING:`
 </git_commit_standards>
+
+<pytest_testing_guidelines>
+- Use fixtures from conftest.py instead of monkeypatch and MagicMock when available
+- For instance, if using libtmux, use provided fixtures: server, session, window, and pane
+- Document in test docstrings why standard fixtures weren't used for exceptional cases
+- Use tmp_path (pathlib.Path) fixture over Python's tempfile
+- Use monkeypatch fixture over unittest.mock
+</pytest_testing_guidelines>