Python 測試驅動開發

測試驅動開發（TDD）的核心循環：RED → GREEN → REFACTOR。

pytest 基礎

import pytest
from calculator import add

def test_add():
    assert add(1, 2) == 3
    assert add(-1, 1) == 0

def test_add_raises():
    with pytest.raises(TypeError):
        add('a', 1)

Fixture

@pytest.fixture
def sample_user():
    return {'name': 'Alice', 'email': 'alice@example.com'}

def test_user_creation(sample_user):
    assert sample_user['name'] == 'Alice'

Parametrize

@pytest.mark.parametrize('a,b,expected', [
    (1, 2, 3),
    (0, 0, 0),
    (-1, 1, 0),
])
def test_add_parametrized(a, b, expected):
    assert add(a, b) == expected

覆蓋率檢查

pytest --cov=src --cov-report=term-missing