Nest.js EWX Worker Node Challenge

Introduction

Hello! Welcome to Energy Web's Typescript and Nest.js challenge. The objective of the challenge is to assess fundamental proficiency in Nest.js and Typescript (or possibly the ability to quickly learn the technology it is new to you).

The challenge scenario is based off of the EWX Worker Node use case. This blog post has more information about EWX. In this challenge, you will implement EWX features in an HTTP API.

The challenge is intended to be a test of fundamental abilities and should be completed in under 2 hours.

Instructions

Please refer to the following instructions in order to complete the challenge.

Installation

First, install the required node.js version.

nvm is recommended. To install and activate required version with nvm, execute:

nvm install

After having required version already required execute:

nvm use # you need to execute this in every terminal used for this project

After having installed the correct node version, to install the required package execute:

$ npm install

Task Requirements

The task is to implement 3 HTTP endpoints. The expected behaviour of these endpoints is:

1. The /vote endpoint should be POST endpoint and should accept a body with the Vote type
2. The /rewarded-accounts endpoint should return an array of account IDs whose vote was a part of the consensus set of votes are are eligible for rewards, based on the data submitted to the /vote endpoint. If consensus has not been reached, an empty array should be return.
3. The /rewarded-accounts/:accountId endpoint should return an { isRewarded: true } object if the provided accountId is a part of the consensus set. It should return { isRewarded: false } otherwise.
4. The consensus logic should be that the first vote value to receive a count greater than CONSENSUS_THRESHOLD is the consensus value.

If you have any questions about the above behaviour, please reach out to ask.

Note

• Data storage may be entirely in application memory. There is no need to configure a database to persist data between requests.
• Please consider the time and space complexity of your implementation if a large number of votes are submitted.

Validating your Implementation

The easiest value to validate your implementation is to use automated tests. An initial end-to-end test is provided and can be run using

$ npm run test:e2e

Please feel free to additional automated tests, either unit or end-to-end.

To run the app to test your implementation manually, you may use:

# development
$ npm run start

# watch mode
$ npm run start:dev

Submission

Please make a clone of this repository and send us either a link to your cloned repository on GitHub or a zipped copy of the cloned repository.