Testing the Mongoose save() method by mocking it in an integration test

Question

Testing the Mongoose save() method by mocking it in an integration test

I am currently facing an issue while trying to create a test scenario. The problem arises with the endpoint I have for a REST-API:

Post represents a Mongoose model.

router.post('/addPost', (req, res) => {
  const post = new Post(req.body);
  post.save()
    .then(() => ... return success)
    .catch((err) => ... return error);
});

My goal is to write a test that verifies if the correct value is returned when save() resolves.

After attempting to mock the save() method within the model, I realized it may not be possible. As mentioned in this thread , save is not a method on the model itself but on the document (an instance of the model).

Even after following the recommended approach from the above-mentioned discussion, I seem to be missing something as I cannot successfully override the save() method.

The code snippet I have so far (factory is sourced from factory-girl as per the instructions provided in the given link. Here is a direct link to the package):

factory.define('Post', Post, {
  save: new Promise((resolve, reject) => {
    resolve();
  }),
});
factory.build('Post').then((factoryPost) => {
  Post = factoryPost;
  PostMock = sinon.mock(Post);
  PostMock.expects('save').resolves({});

  ... perform test
});

I believe my implementation might be off track, but I am unable to pinpoint where I am going wrong. There must be others who have encountered a similar issue before.

javascript unit-testing mongoose promise sinon

Answer 1

Answer №1

If you want to create a stub for the post document, which represents an instance of the Post model, you can achieve this by stubbing the Post.prototype.

For example:

server.ts:

import express from 'express';
import Post from './models/post';
import http from 'http';

const app = express();
app.post('/addPost', async (req, res) => {
  const post = new Post(req.body);
  await post.save();
  res.sendStatus(200);
});

const server = http.createServer(app).listen(3000, () => {
  console.info('Http server is listening on http://localhost:3000');
});

export { server };

models/post.ts:

import { model, Schema } from 'mongoose';

const postSchema = new Schema({
  titie: String,
});

export default model('post', postSchema);

server.integration.spec.ts:

import { server } from './server';
import request from 'supertest';
import Post from './models/post';
import sinon from 'sinon';
import { expect } from 'chai';

after((done) => {
  server.close(done);
});

describe('58820254', () => {
  it('/addPost', (done) => {
    const saveStub = sinon.stub(Post.prototype, 'save').returnsThis();
    request(server)
      .post('/addPost')
      .expect(() => {
        console.log('assert');
        expect(saveStub.calledOnce).to.be.true;
      })
      .expect(200, done);
  });
});

Integration test with full coverage:

Http server is listening on http://localhost:3000
  58820254
assert
    ✓ /addPost


  1 passing (25ms)

-----------------------------|----------|----------|----------|----------|-------------------|
File                         |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-----------------------------|----------|----------|----------|----------|-------------------|
All files                    |      100 |      100 |      100 |      100 |                   |
 58820254                    |      100 |      100 |      100 |      100 |                   |
  server.integration.spec.ts |      100 |      100 |      100 |      100 |                   |
  server.ts                  |      100 |      100 |      100 |      100 |                   |
 58820254/models             |      100 |      100 |      100 |      100 |                   |
  post.ts                    |      100 |      100 |      100 |      100 |                   |
-----------------------------|----------|----------|----------|----------|-------------------|

Source code: https://github.com/mrdulin/mongoose5.x-lab/tree/master/src/stackoverflow/58820254

Answer 2

If you want to create a stub for the post document, which represents an instance of the Post model, you can achieve this by stubbing the Post.prototype.

For example:

server.ts:

import express from 'express';
import Post from './models/post';
import http from 'http';

const app = express();
app.post('/addPost', async (req, res) => {
  const post = new Post(req.body);
  await post.save();
  res.sendStatus(200);
});

const server = http.createServer(app).listen(3000, () => {
  console.info('Http server is listening on http://localhost:3000');
});

export { server };

models/post.ts:

import { model, Schema } from 'mongoose';

const postSchema = new Schema({
  titie: String,
});

export default model('post', postSchema);

server.integration.spec.ts:

import { server } from './server';
import request from 'supertest';
import Post from './models/post';
import sinon from 'sinon';
import { expect } from 'chai';

after((done) => {
  server.close(done);
});

describe('58820254', () => {
  it('/addPost', (done) => {
    const saveStub = sinon.stub(Post.prototype, 'save').returnsThis();
    request(server)
      .post('/addPost')
      .expect(() => {
        console.log('assert');
        expect(saveStub.calledOnce).to.be.true;
      })
      .expect(200, done);
  });
});

Integration test with full coverage:

Http server is listening on http://localhost:3000
  58820254
assert
    ✓ /addPost


  1 passing (25ms)

-----------------------------|----------|----------|----------|----------|-------------------|
File                         |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
-----------------------------|----------|----------|----------|----------|-------------------|
All files                    |      100 |      100 |      100 |      100 |                   |
 58820254                    |      100 |      100 |      100 |      100 |                   |
  server.integration.spec.ts |      100 |      100 |      100 |      100 |                   |
  server.ts                  |      100 |      100 |      100 |      100 |                   |
 58820254/models             |      100 |      100 |      100 |      100 |                   |
  post.ts                    |      100 |      100 |      100 |      100 |                   |
-----------------------------|----------|----------|----------|----------|-------------------|

Source code: https://github.com/mrdulin/mongoose5.x-lab/tree/master/src/stackoverflow/58820254

Testing the Mongoose save() method by mocking it in an integration test

Answer №1

Similar questions

Suggestions for resetting the input field IDs in a cloned div after deletion

What is the best way to link one element to another element?

Angular's alternative to JQUERY for handling file uploads and multipart forms

Creating a variable by using a conditional operation in JavaScript

ReactJS fetching previous data through POST request

Exceeded Limit: Google Maps API cannot process more than 10 destinations at this time

How to stop Accordion from automatically collapsing when clicking on AccordionDetails in Material-UI

Phantom.js: Exploring the Power of setTimeout

es-lint is issuing a warning about the presence of multiple modules within the node_modules directory that have names differing only in their casing

The damping effect in three.js OrbitControls only activates when the mouse is pressed, however there is no damping effect once the

Socket.io is most effective when reconnecting

Syncing data between parent and child components in VueJS using v-bind:sync with an object parameter for bidirectional data flow

I'm stumped trying to understand why I keep getting this syntax error. Any thoughts on how to fix it?

Do you think it's feasible to configure cookies for express-session to never expire?

Information is inaccessible beyond onBeforeMount in the Composition API of Vue 3

Checking and merging arrays in Javascript

Is it possible to integrate a Backbone app as a component within a separate app?

Combining actions in a chain within an NgRx effect for Angular

Integrating Dynamics CRM with an External Source to Trigger Workflows

What is the purpose of the assertEquals() method in JSUnit?