I am currently working on a Typescript project and facing the challenge of adding tests for functions that are responsible for sorting through MongoDB responses to extract meaningful results. To facilitate this, I have set up an in-memory mock of the database. Now, the final step is figuring out how to integrate this mock database into my tests when running them on the functions within my file.
The key file in question is mongoClient.ts, playing a crucial role in managing the MongoClient object that requires mocking:
import { MongoClient } from 'mongodb';
const client = new MongoClient(`${process.env.MONGO_CONNECT}`);
export default client;
Another important file called models.ts imports mongoClient using an ES6 import statement:
import client from '../mongoClient';
In order to tackle this issue, I have leveraged a MongoMemoryServer (via mongodb-memory-server) in my test setup, along with creating a custom class to handle connections to the MongoMemoryServer:
class dbConnection {
server;
connection;
uri;
async init() {
this.server = await MongoMemoryServer.create();
this.uri = await this.server.getUri();
this.connection = await new MongoClient(this.uri);
return this.connection;
}
connect() {
this.connection.connect();
}
getClient() {
return this.connection;
}
getUri() {
return this.uri;
}
async stopIt() {
await this.server.stop();
}
}
Despite my efforts, I have encountered difficulties in properly mocking the import of 'mongoClient' within the created models object in the test (
const models = require('../src/models');jest.doMock(), however, they all seem to lead to errors - including scope-related issues and undefined export problems.
Through multiple iterations and edits, it has become apparent that the execution order of Jest tests plays a crucial role in resolving this issue. Ultimately, by meticulously organizing the mocks within beforeAll() statements and dynamically instantiating the models at the beginning of each test, I was able to ensure that the tests ran smoothly, with the necessary mocking applied effectively.
With these adjustments in place, the tests now execute successfully, marking a positive conclusion to this troubleshooting journey. Life is good!