chore: restore files unintentionally deleted in 6c61a4e
This commit is contained in:
yeuimu
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# Advanced JavaScript Testing Patterns
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Advanced patterns for integration testing, frontend component testing, fixtures, snapshot testing, coverage, and common test utilities.
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## Integration Testing
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### Pattern 1: API Integration Tests
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```typescript
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// tests/integration/user.api.test.ts
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import request from "supertest";
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import { app } from "../../src/app";
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import { pool } from "../../src/config/database";
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describe("User API Integration Tests", () => {
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beforeAll(async () => {
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// Setup test database
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await pool.query("CREATE TABLE IF NOT EXISTS users (...)");
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});
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afterAll(async () => {
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// Cleanup
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await pool.query("DROP TABLE IF EXISTS users");
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await pool.end();
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});
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beforeEach(async () => {
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// Clear data before each test
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await pool.query("TRUNCATE TABLE users CASCADE");
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});
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describe("POST /api/users", () => {
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it("should create a new user", async () => {
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const userData = {
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name: "John Doe",
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email: "john@example.com",
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password: "password123",
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};
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const response = await request(app)
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.post("/api/users")
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.send(userData)
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.expect(201);
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expect(response.body).toMatchObject({
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name: userData.name,
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email: userData.email,
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});
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expect(response.body).toHaveProperty("id");
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expect(response.body).not.toHaveProperty("password");
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});
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it("should return 400 if email is invalid", async () => {
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const userData = {
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name: "John Doe",
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email: "invalid-email",
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password: "password123",
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};
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const response = await request(app)
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.post("/api/users")
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.send(userData)
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.expect(400);
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expect(response.body).toHaveProperty("error");
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});
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it("should return 409 if email already exists", async () => {
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const userData = {
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name: "John Doe",
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email: "john@example.com",
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password: "password123",
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};
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await request(app).post("/api/users").send(userData);
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const response = await request(app)
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.post("/api/users")
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.send(userData)
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.expect(409);
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expect(response.body.error).toContain("already exists");
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});
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});
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describe("GET /api/users/:id", () => {
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it("should get user by id", async () => {
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const createResponse = await request(app).post("/api/users").send({
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name: "John Doe",
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email: "john@example.com",
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password: "password123",
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});
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const userId = createResponse.body.id;
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const response = await request(app)
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.get(`/api/users/${userId}`)
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.expect(200);
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expect(response.body).toMatchObject({
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id: userId,
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name: "John Doe",
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email: "john@example.com",
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});
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});
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it("should return 404 if user not found", async () => {
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await request(app).get("/api/users/999").expect(404);
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});
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});
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describe("Authentication", () => {
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it("should require authentication for protected routes", async () => {
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await request(app).get("/api/users/me").expect(401);
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});
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it("should allow access with valid token", async () => {
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// Create user and login
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await request(app).post("/api/users").send({
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name: "John Doe",
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email: "john@example.com",
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password: "password123",
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});
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const loginResponse = await request(app).post("/api/auth/login").send({
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email: "john@example.com",
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password: "password123",
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});
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const token = loginResponse.body.token;
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const response = await request(app)
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.get("/api/users/me")
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.set("Authorization", `Bearer ${token}`)
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.expect(200);
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expect(response.body.email).toBe("john@example.com");
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});
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});
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});
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```
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### Pattern 2: Database Integration Tests
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```typescript
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// tests/integration/user.repository.test.ts
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import { describe, it, expect, beforeAll, afterAll, beforeEach } from "vitest";
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import { Pool } from "pg";
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import { UserRepository } from "../../src/repositories/user.repository";
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describe("UserRepository Integration Tests", () => {
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let pool: Pool;
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let repository: UserRepository;
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beforeAll(async () => {
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pool = new Pool({
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host: "localhost",
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port: 5432,
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database: "test_db",
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user: "test_user",
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password: "test_password",
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});
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repository = new UserRepository(pool);
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// Create tables
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await pool.query(`
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CREATE TABLE IF NOT EXISTS users (
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id SERIAL PRIMARY KEY,
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name VARCHAR(255) NOT NULL,
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email VARCHAR(255) UNIQUE NOT NULL,
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password VARCHAR(255) NOT NULL,
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
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)
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`);
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});
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afterAll(async () => {
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await pool.query("DROP TABLE IF EXISTS users");
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await pool.end();
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});
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beforeEach(async () => {
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await pool.query("TRUNCATE TABLE users CASCADE");
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});
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it("should create a user", async () => {
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const user = await repository.create({
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name: "John Doe",
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email: "john@example.com",
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password: "hashed_password",
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});
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expect(user).toHaveProperty("id");
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expect(user.name).toBe("John Doe");
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expect(user.email).toBe("john@example.com");
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});
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it("should find user by email", async () => {
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await repository.create({
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name: "John Doe",
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email: "john@example.com",
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password: "hashed_password",
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});
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const user = await repository.findByEmail("john@example.com");
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expect(user).toBeTruthy();
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expect(user?.name).toBe("John Doe");
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});
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it("should return null if user not found", async () => {
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const user = await repository.findByEmail("nonexistent@example.com");
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expect(user).toBeNull();
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});
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});
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```
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## Frontend Testing with Testing Library
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### Pattern 1: React Component Testing
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```typescript
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// components/UserForm.tsx
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import { useState } from 'react';
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interface Props {
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onSubmit: (user: { name: string; email: string }) => void;
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}
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export function UserForm({ onSubmit }: Props) {
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const [name, setName] = useState('');
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const [email, setEmail] = useState('');
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const handleSubmit = (e: React.FormEvent) => {
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e.preventDefault();
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onSubmit({ name, email });
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};
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return (
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<form onSubmit={handleSubmit}>
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<input
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type="text"
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placeholder="Name"
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value={name}
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onChange={(e) => setName(e.target.value)}
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data-testid="name-input"
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/>
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<input
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type="email"
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placeholder="Email"
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value={email}
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onChange={(e) => setEmail(e.target.value)}
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data-testid="email-input"
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/>
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<button type="submit">Submit</button>
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</form>
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);
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}
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// components/UserForm.test.tsx
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import { render, screen, fireEvent } from '@testing-library/react';
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import { describe, it, expect, vi } from 'vitest';
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import { UserForm } from './UserForm';
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describe('UserForm', () => {
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it('should render form inputs', () => {
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render(<UserForm onSubmit={vi.fn()} />);
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expect(screen.getByPlaceholderText('Name')).toBeInTheDocument();
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expect(screen.getByPlaceholderText('Email')).toBeInTheDocument();
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expect(screen.getByRole('button', { name: 'Submit' })).toBeInTheDocument();
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});
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it('should update input values', () => {
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render(<UserForm onSubmit={vi.fn()} />);
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const nameInput = screen.getByTestId('name-input') as HTMLInputElement;
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const emailInput = screen.getByTestId('email-input') as HTMLInputElement;
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fireEvent.change(nameInput, { target: { value: 'John Doe' } });
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fireEvent.change(emailInput, { target: { value: 'john@example.com' } });
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expect(nameInput.value).toBe('John Doe');
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expect(emailInput.value).toBe('john@example.com');
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});
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it('should call onSubmit with form data', () => {
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const onSubmit = vi.fn();
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render(<UserForm onSubmit={onSubmit} />);
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fireEvent.change(screen.getByTestId('name-input'), {
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target: { value: 'John Doe' },
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});
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fireEvent.change(screen.getByTestId('email-input'), {
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target: { value: 'john@example.com' },
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});
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fireEvent.click(screen.getByRole('button', { name: 'Submit' }));
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expect(onSubmit).toHaveBeenCalledWith({
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name: 'John Doe',
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email: 'john@example.com',
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});
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});
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});
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```
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### Pattern 2: Testing Hooks
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```typescript
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// hooks/useCounter.ts
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import { useState, useCallback } from "react";
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export function useCounter(initialValue = 0) {
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const [count, setCount] = useState(initialValue);
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const increment = useCallback(() => setCount((c) => c + 1), []);
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const decrement = useCallback(() => setCount((c) => c - 1), []);
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const reset = useCallback(() => setCount(initialValue), [initialValue]);
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return { count, increment, decrement, reset };
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}
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// hooks/useCounter.test.ts
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import { renderHook, act } from "@testing-library/react";
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import { describe, it, expect } from "vitest";
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import { useCounter } from "./useCounter";
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describe("useCounter", () => {
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it("should initialize with default value", () => {
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const { result } = renderHook(() => useCounter());
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expect(result.current.count).toBe(0);
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});
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it("should initialize with custom value", () => {
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const { result } = renderHook(() => useCounter(10));
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expect(result.current.count).toBe(10);
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});
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it("should increment count", () => {
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const { result } = renderHook(() => useCounter());
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act(() => {
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result.current.increment();
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});
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expect(result.current.count).toBe(1);
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});
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it("should decrement count", () => {
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const { result } = renderHook(() => useCounter(5));
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act(() => {
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result.current.decrement();
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});
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expect(result.current.count).toBe(4);
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});
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it("should reset to initial value", () => {
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const { result } = renderHook(() => useCounter(10));
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act(() => {
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result.current.increment();
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result.current.increment();
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});
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expect(result.current.count).toBe(12);
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act(() => {
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result.current.reset();
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});
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expect(result.current.count).toBe(10);
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});
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});
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```
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## Test Fixtures and Factories
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```typescript
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// tests/fixtures/user.fixture.ts
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import { faker } from "@faker-js/faker";
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export function createUserFixture(overrides?: Partial<User>): User {
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return {
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id: faker.string.uuid(),
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name: faker.person.fullName(),
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email: faker.internet.email(),
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createdAt: faker.date.past(),
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...overrides,
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};
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}
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export function createUsersFixture(count: number): User[] {
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return Array.from({ length: count }, () => createUserFixture());
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}
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// Usage in tests
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import {
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createUserFixture,
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createUsersFixture,
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} from "../fixtures/user.fixture";
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describe("UserService", () => {
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it("should process user", () => {
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const user = createUserFixture({ name: "John Doe" });
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// Use user in test
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});
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it("should handle multiple users", () => {
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const users = createUsersFixture(10);
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// Use users in test
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});
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});
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```
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## Snapshot Testing
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```typescript
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// components/UserCard.test.tsx
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import { render } from '@testing-library/react';
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import { describe, it, expect } from 'vitest';
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import { UserCard } from './UserCard';
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describe('UserCard', () => {
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it('should match snapshot', () => {
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const user = {
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id: '1',
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name: 'John Doe',
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email: 'john@example.com',
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avatar: 'https://example.com/avatar.jpg',
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};
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const { container } = render(<UserCard user={user} />);
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expect(container.firstChild).toMatchSnapshot();
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});
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it('should match snapshot with loading state', () => {
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const { container } = render(<UserCard loading />);
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expect(container.firstChild).toMatchSnapshot();
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});
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});
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```
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## Coverage Reports
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```typescript
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// package.json
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{
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"scripts": {
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"test": "vitest",
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"test:coverage": "vitest --coverage",
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"test:ui": "vitest --ui"
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}
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}
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```
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## Common Patterns
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### Test Organization
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```typescript
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describe("UserService", () => {
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describe("createUser", () => {
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it("should create user successfully", () => {});
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it("should throw error if email exists", () => {});
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it("should hash password", () => {});
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});
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describe("updateUser", () => {
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it("should update user", () => {});
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it("should throw error if not found", () => {});
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});
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});
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```
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### Testing Promises
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```typescript
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// Using async/await
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it("should fetch user", async () => {
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const user = await service.fetchUser("1");
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expect(user).toBeDefined();
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});
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// Testing rejections
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it("should throw error", async () => {
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await expect(service.fetchUser("invalid")).rejects.toThrow("Not found");
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});
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```
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### Testing Timers
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```typescript
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import { vi } from "vitest";
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it("should call function after delay", () => {
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vi.useFakeTimers();
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const callback = vi.fn();
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setTimeout(callback, 1000);
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expect(callback).not.toHaveBeenCalled();
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vi.advanceTimersByTime(1000);
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expect(callback).toHaveBeenCalled();
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vi.useRealTimers();
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});
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```
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