Testing Database Operations Cheat Sheet

Setup

1. Install mongodb-memory-server: npm install mongodb-memory-server --save-dev
2. Import mongodb-memory-server: const { MongoMemoryServer } = require("mongodb-memory-server");
3. Create a function to initialize the in-memory MongoDB server and connect to it using Mongoose.

Example

async function initializeMongoServer() {
  const mongoServer = await MongoMemoryServer.create();
  const mongoUri = mongoServer.getUri();

  mongoose.connect(mongoUri);

  mongoose.connection.on("error", e => {
    if (e.message.code === "ETIMEDOUT") {
      console.log(e);
      mongoose.connect(mongoUri);
    }
    console.log(e);
  });

  mongoose.connection.once("open", () => {
    console.log(`MongoDB successfully connected to ${mongoUri}`);
  });
}

module.exports = initializeMongoServer;

Using the Testing Database

• Call the initializeMongoServer function in your testing file.
• Any operations that work on your MongoDB database will use this testing one instead of your real one.

Additional Notes

• Consider using a beforeAll function in your testing suite to add a couple of items to the database before running tests.
• This is not the only way to set up a testing environment. You could also use nconf, command-line arguments, or other methods to set up a testing environment that uses mongodb-memory-server.
• Always read through the mongodb-memory-server docs and Jest Docs for more details.