Next.js 15 Fullstack (App Router + Server Actions) · 课时

模拟与测试 API 路由

使用 Jest 和 MSW 模拟数据库、网络调用及外部服务，隔离测试 Next.js 路由处理器和服务器操作。

模拟与测试 API 路由 是 CoddyKit 上的免费 Next.js 15 Fullstack (App Router + Server Actions) 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Next.js 15 Fullstack (App Router + Server Actions) 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Next.js 15 Fullstack (App Router + Server Actions) 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Why Mock?

Tests should be fast, deterministic, and isolated. Mocking replaces slow or external dependencies — databases, payment APIs, email senders — with controllable stand-ins so a single failure does not break unrelated tests.

What to Mock

Good mock targets in a Next.js app:

The database client (Prisma)
External HTTP calls (Stripe, OpenAI)
Auth/session helpers

Keep the route's own logic real so you actually test it.

A Simple Route Handler

Here is a route we want to test. It reads a query param and returns JSON.

// app/api/user/route.ts
import { prisma } from '@/lib/prisma';
export async function GET(req: Request) {
  const users = await prisma.user.findMany();
  return Response.json(users);
}

Mocking Prisma with Jest

jest.mock replaces a module. Mock the Prisma module so calls return fixed data instead of hitting a real database.

jest.mock('@/lib/prisma', () => ({
  prisma: {
    user: { findMany: jest.fn() }
  }
}));

Setting Return Values

In each test, tell the mock what to resolve with using mockResolvedValue. This drives the route down a specific path.

import { prisma } from '@/lib/prisma';
(prisma.user.findMany as jest.Mock).mockResolvedValue([
  { id: 1, name: 'Ada' }
]);

Invoking the Handler

Route Handlers are plain functions. Call them directly with a Request and assert on the returned Response.

import { GET } from '@/app/api/user/route';
const res = await GET(new Request('http://test/api/user'));
const data = await res.json();
expect(data[0].name).toBe('Ada');

Asserting Call Behavior

Verify the mock was used correctly with matchers like toHaveBeenCalledWith. This confirms your route passes the right arguments.

expect(prisma.user.findMany).toHaveBeenCalledTimes(1);

Mocking External HTTP with MSW

For outbound calls, MSW (Mock Service Worker) intercepts requests at the network layer. Define handlers that return canned responses.

import { http, HttpResponse } from 'msw';
export const handlers = [
  http.get('https://api.stripe.com/v1/charges', () =>
    HttpResponse.json({ amount: 500 })
  )
];

Starting the Mock Server

Boot the MSW server in your test setup so every test runs against the mocked network. Reset handlers between tests for isolation.

import { setupServer } from 'msw/node';
const server = setupServer(...handlers);
beforeAll(() => server.listen());
afterEach(() => server.resetHandlers());
afterAll(() => server.close());

Testing Error Paths

Make mocks reject or return errors to test how your route handles failures, ensuring it returns the right status code.

(prisma.user.findMany as jest.Mock).mockRejectedValue(new Error('db down'));
const res = await GET(new Request('http://test/api/user'));
expect(res.status).toBe(500);

Best Practices

Keep mocked tests trustworthy:

Mock the edges, keep logic real
Reset mocks between tests
Cover success and error paths
Use MSW for realistic network mocking

Quick Check

Test your mocking knowledge.

Recap

You learned to test routes in isolation:

Mock the Prisma client with jest.mock and mockResolvedValue
Call Route Handlers directly and assert on the Response
Intercept outbound HTTP with MSW
Cover error paths by making mocks reject

Your API tests are now fast and reliable.

常见问题解答

「模拟与测试 API 路由」课时是免费的吗？

是的 — 「模拟与测试 API 路由」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Next.js 15 Fullstack (App Router + Server Actions) 课程的其余内容，请升级到 CoddyKit PRO。 Next.js 15 Fullstack (App Router + Server Actions) 课程共包含 4 节课。

「模拟与测试 API 路由」这节课中我会学到什么？

使用 Jest 和 MSW 模拟数据库、网络调用及外部服务，隔离测试 Next.js 路由处理器和服务器操作。你通过在浏览器中直接运行的动手代码来练习 Next.js 15 Fullstack (App Router + Server Actions)，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Next.js 15 Fullstack (App Router + Server Actions) 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Next.js 15 Fullstack (App Router + Server Actions) 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「模拟与测试 API 路由」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Next.js 15 Fullstack (App Router + Server Actions) 课中编写并运行代码吗？

能。每节 Next.js 15 Fullstack (App Router + Server Actions) 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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