---
name: django-tdd
description: 使用 pytest-django 實施 Django 測試策略、TDD 方法論、factory_boy、Mock 模擬、覆蓋率以及 Django REST Framework API 的測試。
---

# Django TDD 測試實踐

針對 Django 應用程序的使用 pytest、factory_boy 和 Django REST Framework 的測試驅動開發 (TDD)。

## 何時啟用

- 撰寫新 Django 應用程序。
- 實作 Django REST Framework API。
- 測試 Django 模型 (Models)、視圖 (Views) 和序列化程式 (Serializers)。
- 為 Django 專案設置測試基礎設施。

## Django 的 TDD 工作流

### 紅燈-綠燈-重構 週期 (Red-Green-Refactor Cycle)

```python
# 步驟 1: 紅燈 (RED) - 撰寫會失敗的測試
def test_user_creation():
    user = User.objects.create_user(email='test@example.com', password='testpass123')
    assert user.email == 'test@example.com'
    assert user.check_password('testpass123')
    assert not user.is_staff

# 步驟 2: 綠燈 (GREEN) - 讓測試通過
# 建立 User 模型或 Factory 物件

# 步驟 3: 重構 (REFACTOR) - 在保持綠燈狀態下改進程式碼
```

## 環境設置

### pytest 配置

```ini
# pytest.ini
[pytest]
DJANGO_SETTINGS_MODULE = config.settings.test
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts =
    --reuse-db
    --nomigrations
    --cov=apps
    --cov-report=html
    --cov-report=term-missing
    --strict-markers
markers =
    slow: 標記為較慢的測試
    integration: 標記為整合測試
```

### 測試環境設定 (Test Settings)

```python
# config/settings/test.py
from .base import *

DEBUG = True
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': ':memory:',
    }
}

# 為了提升速度而停用遷移 (Migrations)
class DisableMigrations:
    def __contains__(self, item):
        return True

    def __getitem__(self, item):
        return None

MIGRATION_MODULES = DisableMigrations()

# 使用較快的密碼雜湊算法
PASSWORD_HASHERS = [
    'django.contrib.auth.hashers.MD5PasswordHasher',
]

# 郵件後端設定
EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'

# Celery 設定為 Eager 模式
CELERY_TASK_ALWAYS_EAGER = True
CELERY_TASK_EAGER_PROPAGATES = True
```

### conftest.py

```python
# tests/conftest.py
import pytest
from django.utils import timezone
from django.contrib.auth import get_user_model

User = get_user_model()

@pytest.fixture(autouse=True)
def timezone_settings(settings):
    """確保時區一致性。"""
    settings.TIME_ZONE = 'UTC'

@pytest.fixture
def user(db):
    """建立測試用使用者。"""
    return User.objects.create_user(
        email='test@example.com',
        password='testpass123',
        username='testuser'
    )

@pytest.fixture
def admin_user(db):
    """建立管理員使用者。"""
    return User.objects.create_superuser(
        email='admin@example.com',
        password='adminpass123',
        username='admin'
    )

@pytest.fixture
def authenticated_client(client, user):
    """回傳已登入的用戶端。"""
    client.force_login(user)
    return client

@pytest.fixture
def api_client():
    """回傳 DRF API 用戶端。"""
    from rest_framework.test import APIClient
    return APIClient()

@pytest.fixture
def authenticated_api_client(api_client, user):
    """回傳已驗證的 API 用戶端。"""
    api_client.force_authenticate(user=user)
    return api_client
```

## Factory Boy

### Factory 設置

```python
# tests/factories.py
import factory
from factory import fuzzy
from datetime import datetime, timedelta
from django.contrib.auth import get_user_model
from apps.products.models import Product, Category

User = get_user_model()

class UserFactory(factory.django.DjangoModelFactory):
    """User 模型的 Factory。"""

    class Meta:
        model = User

    email = factory.Sequence(lambda n: f"user{n}@example.com")
    username = factory.Sequence(lambda n: f"user{n}")
    password = factory.PostGenerationMethodCall('set_password', 'testpass123')
    first_name = factory.Faker('first_name')
    last_name = factory.Faker('last_name')
    is_active = True

class CategoryFactory(factory.django.DjangoModelFactory):
    """Category 模型的 Factory。"""

    class Meta:
        model = Category

    name = factory.Faker('word')
    slug = factory.LazyAttribute(lambda obj: obj.name.lower())
    description = factory.Faker('text')

class ProductFactory(factory.django.DjangoModelFactory):
    """Product 模型的 Factory。"""

    class Meta:
        model = Product

    name = factory.Faker('sentence', nb_words=3)
    slug = factory.LazyAttribute(lambda obj: obj.name.lower().replace(' ', '-'))
    description = factory.Faker('text')
    price = fuzzy.FuzzyDecimal(10.00, 1000.00, 2)
    stock = fuzzy.FuzzyInteger(0, 100)
    is_active = True
    category = factory.SubFactory(CategoryFactory)
    created_by = factory.SubFactory(UserFactory)

    @factory.post_generation
    def tags(self, create, extracted, **kwargs):
        """為產品增加標籤。"""
        if not create:
            return
        if extracted:
            for tag in extracted:
                self.tags.add(tag)
```

### 使用 Factories

```python
# tests/test_models.py
import pytest
from tests.factories import ProductFactory, UserFactory

def test_product_creation():
    """使用 factory 測試產品建立。"""
    product = ProductFactory(price=100.00, stock=50)
    assert product.price == 100.00
    assert product.stock == 50
    assert product.is_active is True

def test_product_with_tags():
    """測試帶有標籤的產品。"""
    tags = [TagFactory(name='electronics'), TagFactory(name='new')]
    product = ProductFactory(tags=tags)
    assert product.tags.count() == 2

def test_multiple_products():
    """測試建立多個產品。"""
    products = ProductFactory.create_batch(10)
    assert len(products) == 10
```

## 模型測試 (Model Testing)

### 模型測試範例

```python
# tests/test_models.py
import pytest
from django.core.exceptions import ValidationError
from tests.factories import UserFactory, ProductFactory

class TestUserModel:
    """測試 User 模型。"""

    def test_create_user(self, db):
        """測試建立一般使用者。"""
        user = UserFactory(email='test@example.com')
        assert user.email == 'test@example.com'
        assert user.check_password('testpass123')
        assert not user.is_staff
        assert not user.is_superuser

    def test_create_superuser(self, db):
        """測試建立超級使用者。"""
        user = UserFactory(
            email='admin@example.com',
            is_staff=True,
            is_superuser=True
        )
        assert user.is_staff
        assert user.is_superuser

    def test_user_str(self, db):
        """測試使用者字串表示形式。"""
        user = UserFactory(email='test@example.com')
        assert str(user) == 'test@example.com'

class TestProductModel:
    """測試 Product 模型。"""

    def test_product_creation(self, db):
        """測試建立產品。"""
        product = ProductFactory()
        assert product.id is not None
        assert product.is_active is True
        assert product.created_at is not None

    def test_product_slug_generation(self, db):
        """測試自動生成 Slug。"""
        product = ProductFactory(name='Test Product')
        assert product.slug == 'test-product'

    def test_product_price_validation(self, db):
        """測試價格不能為負數。"""
        product = ProductFactory(price=-10)
        with pytest.raises(ValidationError):
            product.full_clean()

    def test_product_manager_active(self, db):
        """測試 active 管理員方法。"""
        ProductFactory.create_batch(5, is_active=True)
        ProductFactory.create_batch(3, is_active=False)

        active_count = Product.objects.active().count()
        assert active_count == 5

    def test_product_stock_management(self, db):
        """測試庫存管理。"""
        product = ProductFactory(stock=10)
        product.reduce_stock(5)
        product.refresh_from_db()
        assert product.stock == 5

        with pytest.raises(ValueError):
            product.reduce_stock(10)  # 庫存不足
```

## 視圖測試 (View Testing)

### Django 視圖測試

```python
# tests/test_views.py
import pytest
from django.urls import reverse
from tests.factories import ProductFactory, UserFactory

class TestProductViews:
    """測試產品視圖。"""

    def test_product_list(self, client, db):
        """測試產品列表視圖。"""
        ProductFactory.create_batch(10)

        response = client.get(reverse('products:list'))

        assert response.status_code == 200
        assert len(response.context['products']) == 10

    def test_product_detail(self, client, db):
        """測試產品詳情視圖。"""
        product = ProductFactory()

        response = client.get(reverse('products:detail', kwargs={'slug': product.slug}))

        assert response.status_code == 200
        assert response.context['product'] == product

    def test_product_create_requires_login(self, client, db):
        """測試建立產品需要身分驗證。"""
        response = client.get(reverse('products:create'))

        assert response.status_code == 302
        assert response.url.startswith('/accounts/login/')

    def test_product_create_authenticated(self, authenticated_client, db):
        """測試以已驗證使用者身分建立產品。"""
        response = authenticated_client.get(reverse('products:create'))

        assert response.status_code == 200

    def test_product_create_post(self, authenticated_client, db, category):
        """測試透過 POST 建立產品。"""
        data = {
            'name': 'Test Product',
            'description': 'A test product',
            'price': '99.99',
            'stock': 10,
            'category': category.id,
        }

        response = authenticated_client.post(reverse('products:create'), data)

        assert response.status_code == 302
        assert Product.objects.filter(name='Test Product').exists()
```

## DRF API 測試

### 序列化程式 (Serializer) 測試

```python
# tests/test_serializers.py
import pytest
from rest_framework.exceptions import ValidationError
from apps.products.serializers import ProductSerializer
from tests.factories import ProductFactory

class TestProductSerializer:
    """測試 ProductSerializer。"""

    def test_serialize_product(self, db):
        """測試序列化產品。"""
        product = ProductFactory()
        serializer = ProductSerializer(product)

        data = serializer.data

        assert data['id'] == product.id
        assert data['name'] == product.name
        assert data['price'] == str(product.price)

    def test_deserialize_product(self, db):
        """測試反序列化產品資料。"""
        data = {
            'name': 'Test Product',
            'description': 'Test description',
            'price': '99.99',
            'stock': 10,
            'category': 1,
        }

        serializer = ProductSerializer(data=data)

        assert serializer.is_valid()
        product = serializer.save()

        assert product.name == 'Test Product'
        assert float(product.price) == 99.99

    def test_price_validation(self, db):
        """測試價格驗證。"""
        data = {
            'name': 'Test Product',
            'price': '-10.00',
            'stock': 10,
        }

        serializer = ProductSerializer(data=data)

        assert not serializer.is_valid()
        assert 'price' in serializer.errors

    def test_stock_validation(self, db):
        """測試庫存不能為負數。"""
        data = {
            'name': 'Test Product',
            'price': '99.99',
            'stock': -5,
        }

        serializer = ProductSerializer(data=data)

        assert not serializer.is_valid()
        assert 'stock' in serializer.errors
```

### API ViewSet 測試

```python
# tests/test_api.py
import pytest
from rest_framework.test import APIClient
from rest_framework import status
from django.urls import reverse
from tests.factories import ProductFactory, UserFactory

class TestProductAPI:
    """測試產品 API 端點。"""

    @pytest.fixture
    def api_client(self):
        """回傳 API 用戶端。"""
        return APIClient()

    def test_list_products(self, api_client, db):
        """測試列表顯示產品。"""
        ProductFactory.create_batch(10)

        url = reverse('api:product-list')
        response = api_client.get(url)

        assert response.status_code == status.HTTP_200_OK
        assert response.data['count'] == 10

    def test_retrieve_product(self, api_client, db):
        """測試獲取單一產品詳情。"""
        product = ProductFactory()

        url = reverse('api:product-detail', kwargs={'pk': product.id})
        response = api_client.get(url)

        assert response.status_code == status.HTTP_200_OK
        assert response.data['id'] == product.id

    def test_create_product_unauthorized(self, api_client, db):
        """測試未經授權建立產品。"""
        url = reverse('api:product-list')
        data = {'name': 'Test Product', 'price': '99.99'}

        response = api_client.post(url, data)

        assert response.status_code == status.HTTP_401_UNAUTHORIZED

    def test_create_product_authorized(self, authenticated_api_client, db):
        """測試以已驗證使用者身分建立產品。"""
        url = reverse('api:product-list')
        data = {
            'name': 'Test Product',
            'description': 'Test',
            'price': '99.99',
            'stock': 10,
        }

        response = authenticated_api_client.post(url, data)

        assert response.status_code == status.HTTP_201_CREATED
        assert response.data['name'] == 'Test Product'

    def test_update_product(self, authenticated_api_client, db):
        """測試更新產品。"""
        product = ProductFactory(created_by=authenticated_api_client.user)

        url = reverse('api:product-detail', kwargs={'pk': product.id})
        data = {'name': 'Updated Product'}

        response = authenticated_api_client.patch(url, data)

        assert response.status_code == status.HTTP_200_OK
        assert response.data['name'] == 'Updated Product'

    def test_delete_product(self, authenticated_api_client, db):
        """測試刪除產品。"""
        product = ProductFactory(created_by=authenticated_api_client.user)

        url = reverse('api:product-detail', kwargs={'pk': product.id})
        response = authenticated_api_client.delete(url)

        assert response.status_code == status.HTTP_204_NO_CONTENT

    def test_filter_products_by_price(self, api_client, db):
        """測試依價格篩選產品。"""
        ProductFactory(price=50)
        ProductFactory(price=150)

        url = reverse('api:product-list')
        response = api_client.get(url, {'price_min': 100})

        assert response.status_code == status.HTTP_200_OK
        assert response.data['count'] == 1

    def test_search_products(self, api_client, db):
        """測試搜尋產品。"""
        ProductFactory(name='Apple iPhone')
        ProductFactory(name='Samsung Galaxy')

        url = reverse('api:product-list')
        response = api_client.get(url, {'search': 'Apple'})

        assert response.status_code == status.HTTP_200_OK
        assert response.data['count'] == 1
```

## Mock 模擬與 Patch 修補

### 模擬外部服務

```python
# tests/test_views.py
from unittest.mock import patch, Mock
import pytest

class TestPaymentView:
    """使用模擬付款閘道器的付款視圖測試。"""

    @patch('apps.payments.services.stripe')
    def test_successful_payment(self, mock_stripe, client, user, product):
        """測試使用模擬 Stripe 的成功付款流程。"""
        # 配置模擬對象
        mock_stripe.Charge.create.return_value = {
            'id': 'ch_123',
            'status': 'succeeded',
            'amount': 9999,
        }

        client.force_login(user)
        response = client.post(reverse('payments:process'), {
            'product_id': product.id,
            'token': 'tok_visa',
        })

        assert response.status_code == 302
        mock_stripe.Charge.create.assert_called_once()

    @patch('apps.payments.services.stripe')
    def test_failed_payment(self, mock_stripe, client, user, product):
        """測試付款失敗的情境。"""
        mock_stripe.Charge.create.side_effect = Exception('Card declined')

        client.force_login(user)
        response = client.post(reverse('payments:process'), {
            'product_id': product.id,
            'token': 'tok_visa',
        })

        assert response.status_code == 302
        assert 'error' in response.url
```

### 模擬郵件發送

```python
# tests/test_email.py
from django.core import mail
from django.test import override_settings

@override_settings(EMAIL_BACKEND='django.core.mail.backends.locmem.EmailBackend')
def test_order_confirmation_email(db, order):
    """測試訂單確認郵件。"""
    order.send_confirmation_email()

    assert len(mail.outbox) == 1
    assert order.user.email in mail.outbox[0].to
    assert 'Order Confirmation' in mail.outbox[0].subject
```

## 整合測試 (Integration Testing)

### 完整流程測試

```python
# tests/test_integration.py
import pytest
from django.urls import reverse
from tests.factories import UserFactory, ProductFactory

class TestCheckoutFlow:
    """測試完整的結帳流程。"""

    def test_guest_to_purchase_flow(self, client, db):
        """測試從訪客到購買的完整流程。"""
        # 步驟 1: 註冊
        response = client.post(reverse('users:register'), {
            'email': 'test@example.com',
            'password': 'testpass123',
            'password_confirm': 'testpass123',
        })
        assert response.status_code == 302

        # 步驟 2: 登入
        response = client.post(reverse('users:login'), {
            'email': 'test@example.com',
            'password': 'testpass123',
        })
        assert response.status_code == 302

        # 步驟 3: 瀏覽產品
        product = ProductFactory(price=100)
        response = client.get(reverse('products:detail', kwargs={'slug': product.slug}))
        assert response.status_code == 200

        # 步驟 4: 加入購物車
        response = client.post(reverse('cart:add'), {
            'product_id': product.id,
            'quantity': 1,
        })
        assert response.status_code == 302

        # 步驟 5: 結帳確認
        response = client.get(reverse('checkout:review'))
        assert response.status_code == 200
        assert product.name in response.content.decode()

        # 步驟 6: 完成購買
        with patch('apps.checkout.services.process_payment') as mock_payment:
            mock_payment.return_value = True
            response = client.post(reverse('checkout:complete'))

        assert response.status_code == 302
        assert Order.objects.filter(user__email='test@example.com').exists()
```

## 測試最佳實踐

### 推薦做法 (DO)

- **使用 Factory**：取代手動建立物件。
- **單一測試單一斷言**：保持測試焦注。
- **具備描述性的測試名稱**：如 `test_user_cannot_delete_others_post`。
- **測試邊界案例**：包含空輸入、None 值、邊界條件等。
- **模擬外部服務**：不要依賴外部 API。
- **使用 Fixtures**：消除程式碼重複。
- **測試權限**：確保授權機制正常工作。
- **保持測試速度**：使用 `--reuse-db` 與 `--nomigrations`。

### 應避免的做法 (DON'T)

- **不要測試 Django 內部機制**：信任 Django 的功能。
- **不要測試第三方套件程式碼**：信任函式庫的功能。
- **不要忽視失敗的測試**：所有測試必須通過。
- **不要讓測試產生相依性**：測試應能以任何順序執行。
- **不要過度 Mock 模擬**：僅針對外部相依關係進行模擬。
- **不要測試私有方法**：測試公開介面即可。
- **不要使用生產環境資料庫**：務必使用測試資料庫。

## 覆蓋率 (Coverage)

### 覆蓋率配置

```bash
# 執行帶有覆蓋率檢查的測試
pytest --cov=apps --cov-report=html --cov-report=term-missing

# 生成 HTML 報告
open htmlcov/index.html
```

### 覆蓋率目標 (Coverage Goals)

| 組件 | 目標覆蓋率 |
|-----------|-----------------|
| 模型 (Models) | 90%+ |
| 序列化程式 (Serializers) | 85%+ |
| 視圖 (Views) | 80%+ |
| 服務 (Services) | 90%+ |
| 工具類 (Utilities) | 80%+ |
| 整體 (Overall) | 80%+ |

## 快速參考

| 模式 | 用法 |
|---------|-------|
| `@pytest.mark.django_db` | 啟用資料庫存取權限 |
| `client` | Django 測試用戶端 |
| `api_client` | DRF API 用戶端 |
| `factory.create_batch(n)` | 建立多個物件 |
| `patch('module.function')` | 模擬外部相依關係 |
| `override_settings` | 暫時更改設定 |
| `force_authenticate()` | 在測試中略過驗證 |
| `assertRedirects` | 檢查重新導向 |
| `assertTemplateUsed` | 驗證範本的使用 |
| `mail.outbox` | 檢查發送的郵件 |

請記住：測試即文件。良好的測試能解釋程式碼應該如何工作。請保持測試簡單、易讀且易於維護。
