Exporting MongooseServerSelectionError and other errors

[kasir-barati]

Do you want to request a feature or report a bug? Yes. I think exposing MongooseServerSelectionError and other custom errors written in Mongoose package should be exported. Why? because then I can do error instanceof MongooseServerSelectionError and It would be much much simpler and secure. It is also helps me to write tests with jest. Test like this

// connect-to-mongodb.config.ts
import mongoose from 'mongoose';
import { serializeError } from 'serialize-error';

import { logger } from './winston.config';
import { Configs } from '../contracts/types/configs.type';

mongoose.Promise = global.Promise;
export let mongooseInstance: typeof mongoose;

export const connectToDb = async (config: Configs) => {
    try {
        if (config.nodeEnv === 'development') {
            mongoose.set('debug', true);
        }
        mongooseInstance = await mongoose.connect(config.db_uri, {
            useNewUrlParser: true,
            useUnifiedTopology: true,
            useFindAndModify: true,
            useCreateIndex: true,
            autoReconnect: true,
            connectTimeoutMS: 100_000,
            reconnectInterval: 10_000,
        });
        logger.info('[conn stat] connected to MongoDb', {
            meta: {
                connectionString: config.db_uri,
            },
        });
    } catch (err) {
        let message = 'During connecting to the mongodb an error occurred';
        if (err.name === 'MongooseServerSelectionError') {
            message = 'Could not connect to the specified connection string';
        }
        logger.error(message, {
            meta: serializeError(err),
        });

        throw err;
    }
};

// connect-to-mongodb.config.test.ts
import { MongooseServerSelectionError } from 'mongoose';

import {
    connectToDb,
    mongooseInstance,
} from '../../src/config/connect-to-mongodb.config';
import { Configs } from '../../src/contracts/types/configs.type';

test('Test connecting to database', function () {
    describe('connect to database failed', function () {
        // @ts-ignore
        const configs: Configs = {
            nodeEnv: 'development',
            db_uri: 'mongodb://user:[email protected]/db-name',
        };
        expect(connectToDb(configs)).toThrowError(MongooseServerSelectionError);
    });
});

What is the current behavior? No access to the errors (MongooseServerSelectionError)

What is the expected behavior? Exporting custom errors from the library. I mean I would like to import { MongooseServerSelectionError } from 'mongoose';

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
NodeJS: 17.3.0
MongooseJS: 5.6.2
MongoDB NodeJS driver: 3.5.1

[vkarpov15]

In 6.2.0 you'll be able to do err instanceof mongoose.Error.MongooseServerSelectionError. Looks like there's already a typedef for this in index.d.ts