「單元測試都過了，為什麼整合起來還是壞掉？」資深工程師搖搖頭，「因為你只測試了零件，沒測試組裝。」

今天，我們要用過去 28 天學到的所有 TDD 技巧，打造一個真正可靠的 Todo API 整合測試套件！

今日旅程地圖

基礎測試 [✅]        Kata 練習 [✅]        框架實戰 [✅]        整合部署 [🔄]
Day 1-10            Day 11-17            Day 18-27           Day 28-30
                                                                 ↑ 我們在這裡！

整合測試的挑戰

# 建立 tests/day29/test_integration_challenge.py
import pytest
from datetime import datetime

def test_why_integration_matters():
    """展示為何需要整合測試"""
    # 單元測試 A: ✅ 通過
    def format_date(date):
        return date.strftime('%Y-%m-%d')
    
    # 單元測試 B: ✅ 通過  
    def calculate_days(start, end):
        return (end - start).days
    
    # 整合時: ❌ 時區問題！
    start = datetime(2024, 1, 1, 0, 0, 0)
    end = datetime(2024, 1, 2, 23, 59, 59)
    days = calculate_days(start, end)
    
    assert days == 1  # 可能失敗！

完整的 Todo App 整合測試

建立 tests/day29/conftest.py

import pytest
import asyncio
from httpx import AsyncClient
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
from sqlalchemy.orm import sessionmaker
from src.todo.main import app
from src.todo.database import Base, get_db

TEST_DATABASE_URL = "sqlite+aiosqlite:///:memory:"

@pytest.fixture(scope="function")
async def test_db():
    """建立測試資料庫"""
    engine = create_async_engine(TEST_DATABASE_URL)
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
    
    TestingSessionLocal = sessionmaker(
        engine, class_=AsyncSession, expire_on_commit=False
    )
    async with TestingSessionLocal() as session:
        yield session
    await engine.dispose()

@pytest.fixture
async def client(test_db: AsyncSession):
    """建立測試客戶端"""
    app.dependency_overrides[get_db] = lambda: test_db
    async with AsyncClient(app=app, base_url="http://test") as ac:
        yield ac
    app.dependency_overrides.clear()

建立 tests/day29/test_todo_integration.py

import pytest
from httpx import AsyncClient
from datetime import datetime

class TestTodoIntegration:
    """Todo 整合測試套件"""
    
    @pytest.mark.asyncio
    async def test_complete_todo_lifecycle(self, client: AsyncClient):
        """測試 Todo 完整生命週期"""
        # 建立新 Todo
        create_response = await client.post(
            "/api/todos",
            json={"title": "整合測試任務", "description": "測試流程"}
        )
        assert create_response.status_code == 201
        todo_id = create_response.json()["id"]
        
        # 取得列表
        list_response = await client.get("/api/todos")
        assert len(list_response.json()) == 1
        
        # 更新 Todo
        update_response = await client.put(
            f"/api/todos/{todo_id}",
            json={"title": "更新任務", "completed": True}
        )
        assert update_response.json()["completed"] is True
        
        # 刪除並確認
        await client.delete(f"/api/todos/{todo_id}")
        verify_response = await client.get(f"/api/todos/{todo_id}")
        assert verify_response.status_code == 404
    
    @pytest.mark.asyncio
    async def test_bulk_operations(self, client: AsyncClient):
        """測試批量操作"""
        # 建立 5 個 Todo
        ids = []
        for i in range(1, 6):
            resp = await client.post("/api/todos", json={"title": f"Task {i}"})
            ids.append(resp.json()["id"])
        
        # 測試分頁
        page1 = await client.get("/api/todos?skip=0&limit=3")
        assert len(page1.json()) == 3
        
        # 更新部分項目並測試篩選
        for i in [0, 2, 4]:
            await client.put(f"/api/todos/{ids[i]}", json={"completed": True})
        
        completed = await client.get("/api/todos?completed=true")
        assert len(completed.json()) == 3

跨元件通訊測試

更新 tests/day29/test_todo_integration.py

import pytest
from httpx import AsyncClient

class TestErrorHandling:
    """錯誤處理整合測試"""
    
    @pytest.mark.asyncio
    async def test_not_found_error(self, client: AsyncClient):
        """測試 404 錯誤"""
        response = await client.get("/api/todos/999")
        assert response.status_code == 404
        assert "not found" in response.json()["detail"].lower()
    
    @pytest.mark.asyncio
    async def test_validation_error(self, client: AsyncClient):
        """測試驗證錯誤"""
        response = await client.post("/api/todos", json={})
        assert response.status_code == 422
        assert "title" in str(response.json()["detail"])
    
    @pytest.mark.asyncio
    async def test_concurrent_updates(self, client: AsyncClient):
        """測試並發更新"""
        response = await client.post("/api/todos", json={"title": "Test"})
        todo_id = response.json()["id"]
        
        import asyncio
        results = await asyncio.gather(
            client.put(f"/api/todos/{todo_id}", json={"title": "V1"}),
            client.put(f"/api/todos/{todo_id}", json={"title": "V2"}),
            return_exceptions=True
        )
        assert all(not isinstance(r, Exception) for r in results)

路由整合測試

更新 tests/day29/test_todo_integration.py

import pytest
import time
import asyncio
from httpx import AsyncClient

class TestPerformance:
    """性能整合測試"""
    
    @pytest.mark.asyncio
    async def test_response_time(self, client: AsyncClient):
        """測試回應時間"""
        await client.get("/api/todos")  # 預熱
        
        start = time.perf_counter()
        response = await client.get("/api/todos")
        elapsed = time.perf_counter() - start
        
        assert response.status_code == 200
        assert elapsed < 0.1  # 應在 100ms 內
    
    @pytest.mark.asyncio
    async def test_load_handling(self, client: AsyncClient):
        """測試負載處理能力"""
        # 建立 20 個 Todo 並同時查詢
        ids = []
        for i in range(20):
            resp = await client.post("/api/todos", json={"title": f"Load {i}"})
            ids.append(resp.json()["id"])
        
        # 並發請求
        start = time.perf_counter()
        results = await asyncio.gather(
            *[client.get(f"/api/todos/{id}") for id in ids]
        )
        elapsed = time.perf_counter() - start
        
        assert all(r.status_code == 200 for r in results)
        assert elapsed < 2.0  # 應在 2 秒內完成

狀態管理整合

更新 tests/day29/test_todo_integration.py

import pytest
import asyncio
from httpx import AsyncClient

class TestDataConsistency:
    """資料一致性測試"""
    
    @pytest.mark.asyncio
    async def test_timestamp_consistency(self, client: AsyncClient):
        """測試時間戳一致性"""
        response = await client.post("/api/todos", json={"title": "Time"})
        created_at = response.json()["created_at"]
        
        await asyncio.sleep(0.1)
        update = await client.put(
            f"/api/todos/{response.json()['id']}",
            json={"title": "Updated"}
        )
        
        assert update.json()["created_at"] == created_at
        assert update.json()["updated_at"] > created_at
    
    @pytest.mark.asyncio
    async def test_transaction_consistency(self, client: AsyncClient):
        """測試事務一致性"""
        # 無效請求不應影響資料庫
        await client.post("/api/todos", json={"title": "x" * 300})
        response = await client.get("/api/todos")
        assert len(response.json()) == 0

完整實作：整合測試套件

完整實作 tests/day29/complete_integration_test.py

# 完整的整合測試套件程式碼
# （與上面的測試內容結合）

實戰經驗：測試金字塔

# 測試金字塔概念
def test_pyramid_concept():
    # 單元測試：多且快
    unit_tests = 100
    integration_tests = 20
    e2e_tests = 5
    
    assert unit_tests > integration_tests > e2e_tests

整合測試的關鍵要點

• 測試完整工作流程
• 邊界條件處理
• 效能測試策略
• API 版本控制
• 錯誤處理機制
• 跨服務整合

今日回顧

今天我們完成了完整的整合測試實戰：

已達成

1. 整合測試策略 - 建立完整的測試架構
2. 跨元件通訊 - 測試元件間的互動
3. 路由整合 - 驗證導航流程
4. 狀態管理 - 確保狀態同步
5. 端到端流程 - 完整使用者旅程

重要觀念

• 整合測試填補單元測試的空缺
• 測試真實的使用者流程
• 確保系統整體運作正常

明日預告

明天是我們 30 天旅程的最後一天！我們將：

• 回顧整個學習歷程
• 總結 TDD 的核心概念
• 分享實戰應用經驗
• 提供持續精進的方向

記住：好的整合測試就像是系統的守護者，它確保所有組件能夠和諧地協同工作！