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My DB Class to test
I have a DB class where i encapsulate Mongodb methods to test
My DB Class to test
import mongodb from 'mongodb';
import dotenv from 'dotenv';

// Comfigure dotenv
dotenv.config();

// eslint-disable-next-line no-unused-vars
class DBClient {
/**
Creates a new DBclient instance.
*/
constructor() {
const host = process.env.DB_HOST || 'localhost';
const port = process.env.DB_PORT || 27017;
const database = process.env.DB_DATABASE || 'files_manager';

const dbUri = `mongodb://${host}:${port}/${database}`;
this.client = new mongodb.MongoClient(dbUri, {
useNewUrlParser: true,
useUnifiedTopology: true,
});

this.isClientConnected = false;
this.client.connect((err) = {
if (err) {
console.error('Error encounted while connecting to MongoDB', err);
} else {
this.isClientConnected = true;
console.log('Connected to MongoDB');
}
});
}

/**
check the status of the connection to MongoDB
@returns {boolean}
*/
isAlive() {
return this.isClientConnected;
}
}

const dbClient = new DBClient();
module.exports = dbClient;

import mongodb from 'mongodb';
import dotenv from 'dotenv';

// Comfigure dotenv
dotenv.config();

// eslint-disable-next-line no-unused-vars
class DBClient {
/**
Creates a new DBclient instance.
*/
constructor() {
const host = process.env.DB_HOST || 'localhost';
const port = process.env.DB_PORT || 27017;
const database = process.env.DB_DATABASE || 'files_manager';

const dbUri = `mongodb://${host}:${port}/${database}`;
this.client = new mongodb.MongoClient(dbUri, {
useNewUrlParser: true,
useUnifiedTopology: true,
});

this.isClientConnected = false;
this.client.connect((err) = {
if (err) {
console.error('Error encounted while connecting to MongoDB', err);
} else {
this.isClientConnected = true;
console.log('Connected to MongoDB');
}
});
}

/**
check the status of the connection to MongoDB
@returns {boolean}
*/
isAlive() {
return this.isClientConnected;
}
}

const dbClient = new DBClient();
module.exports = dbClient;

My Test File
My intention is to mock the connection to db then test
My Test File
const { expect } = require('chai');
const sinon = require('sinon');
const mongodb = require('mongodb');
const dbClient = require('../utils/db');

describe('DBClient', function() {
afterEach(function() {
// Automatically restore all stubs after each test
sinon.restore();
});

it('should initialize and connect successfully', function(done) {
const connectStub = sinon.stub(mongodb.MongoClient.prototype, 'connect').callsFake(function(cb) {
cb(null); // No Error
});
// Wait for the next tick to allow the callback to execute
process.nextTick(() = {
expect(dbClient.isAlive()).to.be.true;
expect(connectStub.calledOnce).to.be.true;
done();
});
});

it('should fail to connect and isAlive returns false', function(done) {
// Stub the connect method to simulate a connection failure
const connectStub = sinon.stub(mongodb.MongoClient.prototype, 'connect').callsFake(function(cb) {
cb(new Error('Failed to connect'));
});

process.nextTick(() = {
expect(dbClient.isAlive()).to.be.false;
expect(connectStub.calledOnce).to.be.true();
done()Source of the question:
https://stackoverflow.com/questions/7...

Question and source license information:
https://meta.stackexchange.com/help/l...
https://stackoverflow.com/