Python Testing Skill

Generate pytest tests following project best practices.

Core Principles

1. Minimal Mocking: Only mock external dependencies (APIs, DBs, file I/O)
2. Parametrization: Use @pytest.mark.parametrize for multiple cases
3. Shared Fixtures: Place reusable fixtures in tests/conftest.py
4. 1-1 Correspondence: src/module.py → tests/test_module.py

Instructions

1. Analyze: Read module to understand functions, dependencies, edge cases
2. Check conftest.py: Identify existing fixtures, plan new ones
3. Mock Only: External HTTP, DB, file I/O, system calls, time
4. Write Tests: Arrange-Act-Assert pattern, clear names
5. Update conftest.py: Add reusable fixtures

Test Structure

"""Tests for module_name (src/module.py)"""
import pytest

class TestClassName:
    """Test ClassName functionality"""

    def test_happy_path(self, fixture):
        """Test normal operation"""
        # Arrange, Act, Assert

    @pytest.mark.parametrize("input,expected", [...])
    def test_variations(self, input, expected):
        """Test multiple inputs"""

    def test_error_handling(self):
        """Test exception cases"""
        with pytest.raises(ExpectedException):
            ...

Checklist

• All public methods tested
• Edge cases (None, 0, empty, max)
• Error conditions raise expected exceptions
• Similar tests parametrized
• Reusable fixtures in conftest.py
• Mocking limited to external deps only