Observer function simulated by SinonStub

Question

Observer function simulated by SinonStub

I am currently testing express middleware using sinon.js

My goal is to verify that it sends a specific JSON response and prevents the request from moving on to the next middleware or request handler.

const middleware = (req: Request, res: Response, next: NextFunction) => {
  setTimeout(() => res.json({status: 'blocked'}), 1000);
}

To mock the Request and Response objects, I am utilizing sinon-express-mock. This allows me to have every property and method in the Response object as a SinonStub.

The issue I am encountering is that when I invoke the middleware and the json method is triggered, I am unsure how to check it afterwards.

Is there a listener or observer available for SinonStub?

Thank you.

javascript typescript express chai sinon

Answer 1

Answer №1

Below is the solution for the unit test:

index.ts:

import { NextFunction, Response, Request } from 'express';

const middleware = (req: Request, res: Response, next: NextFunction) => {
  setTimeout(() => res.json({ status: 'blocked' }), 1000);
};

export { middleware };

index.test.ts:

import { middleware } from './';
import { Request } from 'express';
import sinon, { SinonFakeTimers } from 'sinon';

describe('56676480', () => {
  let clock: SinonFakeTimers;
  before(() => {
    clock = sinon.useFakeTimers();
  });
  after(() => {
    clock.restore();
  });
  it('Test should be successful', () => {
    const mReq = {} as Request;
    const mRes = { json: sinon.stub() } as any;
    const mNext = sinon.stub();
    middleware(mReq, mRes, mNext);
    clock.tick(1000);
    sinon.assert.calledWithExactly(mRes.json, { status: 'blocked' });
  });
});

Results of the unit test with 100% coverage:

  56676480
    ✓ Test should be successful


  1 passing (12ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |                   
 index.ts |     100 |      100 |     100 |     100 |                   
----------|---------|----------|---------|---------|-------------------

Answer 2

Below is the solution for the unit test:

index.ts:

import { NextFunction, Response, Request } from 'express';

const middleware = (req: Request, res: Response, next: NextFunction) => {
  setTimeout(() => res.json({ status: 'blocked' }), 1000);
};

export { middleware };

index.test.ts:

import { middleware } from './';
import { Request } from 'express';
import sinon, { SinonFakeTimers } from 'sinon';

describe('56676480', () => {
  let clock: SinonFakeTimers;
  before(() => {
    clock = sinon.useFakeTimers();
  });
  after(() => {
    clock.restore();
  });
  it('Test should be successful', () => {
    const mReq = {} as Request;
    const mRes = { json: sinon.stub() } as any;
    const mNext = sinon.stub();
    middleware(mReq, mRes, mNext);
    clock.tick(1000);
    sinon.assert.calledWithExactly(mRes.json, { status: 'blocked' });
  });
});

Results of the unit test with 100% coverage:

  56676480
    ✓ Test should be successful


  1 passing (12ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |                   
 index.ts |     100 |      100 |     100 |     100 |                   
----------|---------|----------|---------|---------|-------------------

Observer function simulated by SinonStub

Answer №1

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