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Setup in-memory database for testing Node.js and Mongoose

Dmytro Rykhlyk on February 16, 2021

I've been working on creating an application using Node.js and Mongoose where all data stored in the cloud MongoDB Atlas. My goal was to test API e...
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tperrinweembi profile image
tperrin •

Thanks for this awsome article. But since mongodb-memory-server version 7.0.0 we can't use anymore const mongoServer = new MongoMemoryServer(); but must use instead const mongo = await MongoMemoryServer.create(); . But I didn't succeed to adapt this to your code since that make me run await at file top level so I got the error "SyntaxError: await is only valid in async function". How would do you migrate your code to version 7?

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ryuuto829 profile image
Dmytro Rykhlyk •

Thank you for your comment!
I've updated article using the latest @7.2.1 version of mongodb-memory-server.
Basically, I define a new instance of "MongoMemoryServer" in the connect async function to automatically start server:

/tests/db.js

- const mongoServer = new MongoMemoryServer();
+ let mongoServer;

const connect = async () => {
  await mongoose.disconnect();
+ mongoServer = await MongoMemoryServer.create();

// ...
};
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tperrinweembi profile image
tperrin •

Ok! thanks a lot for your answer

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tperrinweembi profile image
tperrin •

Simply move the create() into the connect method. Thanks! (answer from this article : dev.to/paulasantamaria/testing-nod...)

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nicolasbellini profile image
nicolasbellini •

Hello, thanks for your guide.
How do i test something that requires a JWK, since i first need to create something in the DB for it to provide a token and then use that token for the update request

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ryuuto829 profile image
Dmytro Rykhlyk • • Edited

Hi, thank you :)
Its a good question! Please, check my updated Github repo where I added a simple authentication using JWT and some tests.

My solution is based on this issue

// auth.test.js

describe('POST /api/user/signup', () => {
  test('It should return protected page if token is correct',  async done => {
  // Store our cookies
    let Cookies;

    // Create a new user
    await agent
      .post('/api/user/signup')
      .send({ email: 'hello@world.com', password: '123456' })
      .expect(201)
      .then(res => {
        expect(res.body.user).toBeTruthy();

        // Save the cookie to use it later to retrieve the session
        Cookies = res.headers['set-cookie'].pop().split(';')[0];
      });

    const req = agent.get('/');
    req.cookies = Cookies;

    req.end(function(err, res) {
      if (err) {return done(err);}

      expect(res.text).toBe('Protected page');
      expect(res.status).toBe(200);
      done();
    });
  });
});
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You can create a user and generate a token in each test or just populate it through beforeAll:

beforeAll(async () => {
  await db.connect();
  // create user
});
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parveen99 profile image
parveen99 •

Hi great article. My project is also very similar. How can I learn how to write unit tests using mongo in memory server. Its my first time writing unit tests as a developer.

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ryuuto829 profile image
Dmytro Rykhlyk • • Edited

Thank you!
It's hard for me to give you some concrete advice, I'm still learning how to write tests :) For my small project though, I've tried to write tests for each API endpoint using superset, Jest and mongodb-memory-server official documentations along with some examples.

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Ocholla-T •

Created a dev.to account just to heart this article.

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ryuuto829 profile image
Dmytro Rykhlyk •

Thanks a lot! 😉

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Cédric Gourville •

Hey thx for the article. In the function clear from the db file in test. I think deleMany should have an empty object as parameter

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ryuuto829 profile image
Dmytro Rykhlyk • • Edited

Hi, thank you!
I've tested it with / without empty object and in both cases, all data was properly deleted after each test, so everything should work fine.
Anyway, I'll add it as in the MongoDB documentation. Thx :)

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Egide Kamuzinzi •

I have followed your post but still getting errors on my project.

ReferenceError: regeneratorRuntime is not defined
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Any help?

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navyaharish profile image
navyaharish •

Do you have any similar repo with examples for nestJs testing using mongoMemoryServer?

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Dmytro Rykhlyk •

Sorry, I don't have examples for nestJs 😔