Unit testing Express endpoints with Sinon

userRouterTest.js

// eslint-disable-next-line
const should = require('should')
const sinon = require('sinon');
const proxyquire = require('proxyquire');

describe('userRouter', () => {
  let expressStub;
  let controllerStub;
  let RouterStub;
  let rootRouteStub;
  let idRouterStub;

  before(() => {
    rootRouteStub = {
      get: sinon.stub().callsFake(() => rootRouteStub),
      post: sinon.stub().callsFake(() => rootRouteStub),
    };

    idRouterStub = {
      get: sinon.stub().callsFake(() => idRouterStub),
      put: sinon.stub().callsFake(() => idRouterStub),
      delete: sinon.stub().callsFake(() => idRouterStub),
    };

    RouterStub = {
      route: sinon.stub().callsFake((route) => {
        if (route === '/:id') {
          return idRouterStub;
        }

        return rootRouteStub;
      }),
    };

    expressStub = {
      Router: sinon.stub().returns(RouterStub),
    };

    controllerStub = {
      getAll: sinon.mock(),
      getOne: sinon.mock(),
    };

    proxyquire('../routes/userRouter.js',
      {
        express: expressStub,
        usersController: controllerStub,
      })({});
  });

  it('should map /users get router with getAll controller', () => {
    sinon.assert.calledWith(RouterStub.route, '/users');
    sinon.assert.calledWith(rootRouteStub.get, controllerStub.getAll);
  });

  it('should map /users/:id get router with getOne controller', () => {
    sinon.assert.calledWith(RouterStub.route, '/users/:id');
    sinon.assert.calledWith(idRouterStub.get, controllerStub.getOne)
  });
});

// BASED ON: https://stackoverflow.com/questions/38190712/how-to-unit-test-a-node-api-using-sinon-express-with-mongo-db