---
name: testing-skill
description: Testing best practices for Python and general projects. Use when writing unit tests, debugging test failures, or improving test coverage.
---

# Testing Skill

## Test Structure (AAA Pattern)

```python
def test_decision_layer_returns_action():
    # Arrange
    state = {"health": 80, "enemy_visible": True}

    # Act
    action = decision_layer.decide(state)

    # Assert
    assert action == "attack"
```

## Pytest Tips

### Parametrize to Avoid Duplication
```python
import pytest

@pytest.mark.parametrize("health,expected", [
    (100, "idle"),
    (30,  "flee"),
    (0,   "dead"),
])
def test_state_by_health(health, expected):
    assert get_state(health) == expected
```

### Use Fixtures for Shared Setup
```python
@pytest.fixture
def mock_vision():
    return {"objects": ["enemy", "wall"], "confidence": 0.95}

def test_understanding_layer(mock_vision):
    result = understanding_layer.parse(mock_vision)
    assert "enemy" in result["threats"]
```

## What to Test
- ✅ Happy path (normal input)
- ✅ Edge cases (empty, None, boundary values)
- ✅ Error paths (invalid input raises expected exception)
- ❌ Don't test implementation details — test behavior