How to unit test express Router routes

If you just want to unit test the route’s presence and its method, you can do something like this:

auth.router.js

import { Router } from 'express';

const router = Router();

router.post('/signup', signupValidation, signupUser);
router.post('/login', loginValidation, loginUser);
router.post('/reset', resetValidation, setPasswordReset);

export default router;

auth.router.spec.js

test('has routes', () => {
  const routes = [
    { path: '/signup', method: 'post' },
    { path: '/login', method: 'post' },
    { path: '/reset', method: 'post' },
  ]

it.each(routes)('`$method` exists on $path', (route) => {
  expect(router.stack.some((s) => Object.keys(s.route.methods).includes(route.method))).toBe(true)
  expect(router.stack.some((s) => s.route.path === route.path)).toBe(true)
})

Note: The use of $variables in the example test name will only work with Jest ^27.0.0

Edit: Thanks to Keith Yeh for his suggestion to put this into an each() statement. I have updated the code accordingly & the old code is below:

auth.router.spec.js (OLD)

import router from '../auth.router';

test('has routes', () => {
  const routes = [
    { path: '/signup', method: 'post' },
    { path: '/login', method: 'post' },
    { path: '/reset', method: 'post' }
  ]

  routes.forEach((route) => {
    const match = router.stack.find(
      (s) => s.route.path === route.path && s.route.methods[route.method]
    );
    expect(match).toBeTruthy();
  });
});