/busuu-backend-engineer

Primary LanguageTypeScript

Busuu Backend Engineer Test (NodeJS)

The main goal is create a new project with two API endpoints.

  • Get all Exercises
  • Create an Exercise

The implementation I have done is more complex that it needs to be considering the main goal, however this is how I would setup a new project thinking on the scalability.

Setup

Requirements

  1. node
  2. docker

Installation

$ npm install

Running the app

$ make start

# Onl first time
$ npm run migrations:run

App running in http://localhost:3000

Use-cases

  • Users
    • View all users: GET to http://localhost:3000/users
    • Create: POST to http://localhost:3000/users body example: { name: 'exampleName' }
  • Exercises
    • View all exercises: GET to http://localhost:3000/exercises
    • Create: POST to http://localhost:3000/exercises, body example: { userId: '36a24320-418a-4ff8-bd00-12ca6ce2e19f', content: 'exercise content' }

Notes

  • This test has been implemented using Nest framework TypeScript.
  • Using docker for postgres and node to run the app locally.
  • Separating modules by responsibilities.
  • Basic DDD approach with hexagonal architecture.
  • Easy understand from the folder structure to know what the application is doing just by reading the use cases
  • The migration infrastructure is setup to be used, I mean it's not autogenerated.
  • Using typeorm, but not using Active Record, so using data mapper pattern by repositories.
  • There is coupling in the entities at the domain level šŸ¤®, which is wrong. The correct thing to do would be to have an implementation at the infrastructure level and avoid the coupling at domain level.
  • I added a test file for the use-case to create an exercise. I had some problems mocking the repository, but I left the test implemented as it should, with the mention that with more time I would create a different implementation for that.
  • Created some custom exceptions at domain level. I could create more and with more details.
  • Using class-validator to validate body requests (Not domain rules).

Stay in touch

  • Author - Gonzalo Barba