Vitest Unit Test for API Handlers

import { describe, it, expect, beforeAll } from 'vitest';
import request from 'supertest';
import express from 'express';

function buildApp() {
  const app = express();
  app.use(express.json());

  app.post('/feedback', (req, res) => {
    const { rating, comment } = req.body ?? {};
    if (!Number.isInteger(rating) || rating < 1 || rating > 5) {
      return res.status(400).json({ error: 'rating must be 1-5' });
    }
    return res.status(201).json({ received: true, length: comment.length });
  });
  return app;
}

let app;
beforeAll(() => { app = buildApp(); });

describe('POST /feedback', () => {
  it('accepts a valid rating and returns 201', async () => {
    const res = await request(app)
      .post('/feedback')
      .send({ rating: 5, comment: 'great' });
    expect(res.status).toBe(201);
    expect(res.body.received).toBe(true);
  });

  it('rejects out-of-range rating with 400', async () => {
    const res = await request(app)
      .post('/feedback')
      .send({ rating: 9, comment: 'x' });
    expect(res.status).toBe(400);
    expect(res.body.error).toMatch(/rating/);
  });

  it('rejects missing body with 400', async () => {
    const res = await request(app).post('/feedback').send({});
    expect(res.status).toBe(400);
  });
});