No puedo hacer que esta prueba funcione. Siempre devuelve:

TypeError: no se puede leer la propiedad 'ser' de indefinido

paquete.json (dependencias de desarrollo)

 "chai": "^4.3.6", "chai-as-promised": "^7.1.1", "mocha": "^10.0.0", "sinon": "^9.0.1", "sinon-chai": "^3.7.0", "supertest": "^4.0.2", "ts-node": "^10.7.0",

.mocharc

 { "diff": true, "extension": ["ts"], "package": "./package.json", "reporter": "spec", "slow": "75", "timeout": "2000", "ui": "bdd", "watch-files": ["test/*.ts"], "require": ["ts-node/register"] }

mytest.spec.ts

 import * as request from 'supertest'; import * as sinon from 'sinon'; import * as express from 'express'; import * as appSetup from '../src/app'; describe('Requests handler', () => { let app: express.Application; before(async function (): Promise<void> { app = await appSetup.init(); }); describe('Success', () => { it('Should success', async () => { const payload = { name: 'name', age: 20 }; const resp = await request(app) .post('/my/url') .set('Content-Type', 'application/json'); .send(payload) resp.status.should.be.equal(201); // Here is undefined. }); }); });

PERO, si uso chai espero que funcione;

 import { expect } from 'chai'; expect(resp.status).to.be.equal(201); // WORKS

¿Por qué recibo este error cuando uso sinon?