franciscorafart / medallion

nft-test

TypeScript NFT exercise

A brief exercise to create an NFT-like object in TypeScript (or JavaScript).

Motivation

This exercise is designed to allow you to show in under an hour:

• you write readable, maintainable code
• you can implement a simply specified system
• you're comfortable with typed code (optional)

If you're new to Blockchain and NFTs, you might find it interesting!

In a hurry

• Clone this repository
• Install the dependencies npm install^[1]
• Create a new file src/nft.ts^[2]
• Export a default function of type NFTCreateFn
• Implement necessary interfaces & types in src/supporting.ts
• Run the tests to verify your solution npm test^[3]
• Email your solution to [e-mail]

The problem

At a basic level, the Ethereum NFT (ERC721) spec allows tracking ownership of distinguishable assets. Each owner is represented by a string address, and each asset by a unique integer.

To complete this exercise you'll create a TypeScript object (or class) which keeps track of assets and their owners, implementing the following methods:

• balanceOf returns the number of assets held by an owner
• ownerOf returns the owner of a specific asset
• transferFrom transfers an asset from one owner to another

Your solution should take the form of a function which accepts a list of owners and balances to initialise the assets (with sequential, zero-indexed, integer identifiers) and returns an object implementing these methods.

const owners: NFTHolder[] = [["0xAB…CD", 2], …, ["0x12…34", 1]];

We'll check your submission against the provided test suite, which is based on the comments found in src/supporting.ts. However, we're looking for a good approach to the problem, not a perfect solution.

Submitting

Please send your solution to [e-mail] in whatever form you prefer, just do you best to make it easy for us to access, and parse (no JPEGs!)

Supporting files

While you only need to submit a single .ts (or .js) file, we've provided a basic development environment help make things easier:

• src/supporting.ts predefined types and interfaces
• src/nft.spec.ts a test suite for the exercise
• .mocharc.json configuration for running tests
• package.json, package-lock.json development dependencies
• tsconfig.json TypeScript configuration for the exercise
• README.md the instructions you're reading right now!

Notes

1. Feel to use another package manager if you'd like
2. You can use plain JS, although we'd prefer TypeScript
3. Running (and passing) the tests is optional