Vitest と呼ばれるテスティングフレームワークがめちゃくちゃ早いらしいな

npm init vite@latest my-vitest-app --template vue-ts

npm install -D vitest

  "scripts": {
    "test": "vitest",
    "test:watch": "vitest -w",
    "coverage": "vitest --coverage"
  },

const add = (num1: number, num2: number): number => {
  return num1 * num2;
}
 
export default add;

import { describe, it, expect } from 'vitest'
import add from '../add'
 
describe('add', () => {
  it('should add two numbers', () => {
    expect(add(1, 2)).toBe(3)
  })
})

npm run test:watch
 
> [email protected] test:watch ~/my-vitest-app
> vitest -w
 
 WATCH  ~/my-vitest-app
 
 ❯ src/test/add.spec.ts (1)
   ❯ add (1)
     × should add two numbers
 
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 FAIL  src/test/add.spec.ts > add > should add two numbers
AssertionError: expected 2 to equal 3
 ❯ Proxy.<anonymous> node_modules/vitest/dist/vi-67e478ef.js:505:17
 ❯ Proxy.methodWrapper node_modules/chai/lib/chai/utils/addMethod.js:57:25
 ❯ src/test/add.spec.ts:6:22
      4| describe('add', () => {
      5|   it('should add two numbers', () => {
      6|     expect(add(1, 2)).toBe(3)
       |                      ^
      7|   })
      8| })
 
  - Expected   3
  + Received   2
 
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Test Files  1 failed (1)
     Tests  1 failed (1)
      Time  2.35s (in thread 6ms, 42608.54%)
 
 FAIL  Tests failed. Watching for file changes...
press any key to exit...

 const add = (num1: number, num2: number): number => {
-   return num1 * num2; 
+   return num1 + num2;
 }
 
 export default add;

Re-running tests... [ src/add.ts ]
 
 √ src/test/add.spec.ts (1)
 
Test Files  1 passed (1)
     Tests  1 passed (1)
      Time  3ms
 
 PASS  Waiting for file changes...

import { defineConfig } from 'vite'
 
export default defineConfig({
  test: {
    global: true,
  },
})

{
  "compilerOptions": {
    "types": ["vitest/global"]
  }
}

import axios from 'axios';
 
interface User {
  id: number;
  name: string;
}
 
const fetchUsers = async () => {
  const { data } = await axios.get<User[]>('/api/users');
  return data.map(user => user.name)
}
 
export default fetchUsers;

import { describe, it, expect, vi } from "vitest";
import fetchUsers from "../fetchUsers";
import axios from "axios";
 
vi.mock("axios", () => ({
  get: vi.fn(() => Promise.resolve({
    data: [
      { id: 1, name: "John" },
      { id: 2, name: 'Jane' }
    ]
  }))
}))
 
describe('fetchUsers', () => {
 
  it('should fetch users', async () => {
    const users = await fetchUsers();
    expect(axios.get).toHaveBeenCalledWith('/api/users');
    expect(users).toEqual(['John', 'Jane']);
  });
})

const dayOfWeeks = {
  0: '日曜日',
  1: '月曜日',
  2: '火曜日',
  3: '水曜日',
  4: '木曜日',
  5: '金曜日',
  6: '土曜日'
} as const
 
type Day = keyof typeof dayOfWeeks;
 
const getCurrentDayOfWeek = () => {
  const date = new Date();
  const day = date.getDay() as Day;
  return dayOfWeeks[day];
}
 
export default getCurrentDayOfWeek;

import { describe, it, expect, vi, afterEach } from "vitest";
import getCurrentDayOfWeek from "../getCurrentDayOfWeek";
 
describe('getCurrentDayOfWeek', () => {
 
  afterEach(() => {
    vi.resetAllMocks()
  })
 
  it('should return "土曜日"', () => {
    vi.mockCurrentDate(new Date('2021-12-24'));
    expect(getCurrentDayOfWeek()).toBe("金曜日");
  })
})