Coding Assessment Tasks

Intro

This is a URL shortener that has been created by a junior engineer. Your task is to review the solution, check that it works, and find any errors they may have made, as well as complete the fixes and TODOs listed below.

This solution has been pre-seeded with data in the database already.

Note that these are not necessarily in the order you will need to address them.

Fixes

• Fix Delete Behavior: The client has reported strange behavior when clicking on delete on a URL. Investigate and fix the issue.
• Generate Alias: Implement the generateAlias function.
• UI Implementation: Build out the UI to display the URLs on the main page.

TODO

• Add paging for retrieval of the URLs.
• Sort URLs by their creation date.
• Create the Docker commands to run the solution.
• Replace this README with an appropriate one.

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Snip – URL Shortener

A full-stack URL shortener built with Java Spring Boot (backend) and React + TypeScript (frontend), containerized with Docker.

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Architecture

frontend/      React + TypeScript (Vite)
backend/       Java Spring Boot Web API + SQLite
docker-compose.yml       Orchestrates both services

The frontend proxies API calls through Nginx in production, so there are no CORS concerns once containerized. In development, Vite's dev server proxies to the local API.

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API Reference

The API exposes the same contract expected by the existing frontend.

Method	Path	Description
POST	/shorten	Create a shortened URL
GET	/urls	List all shortened URLs
GET	/{alias}	Redirect to the full URL
DELETE	/{alias}	Delete a shortened URL

POST /shorten

// Request
{
  "fullUrl": "https://example.com/very/long/path",
  "customAlias": "my-alias"   // optional
}

// Response 201
{
  "alias": "my-alias",
  "fullUrl": "https://example.com/very/long/path",
  "shortUrl": "http://localhost:8080/my-alias"
}

Returns 400 if the URL is invalid, the alias is malformed, or the alias is already taken.

GET /urls

// Response 200
[
  {
    "alias": "my-alias",
    "fullUrl": "https://example.com/very/long/path",
    "shortUrl": "http://localhost:8080/my-alias"
  }
]

GET /{alias}

Returns 302 Redirect to the full URL, or 404 if the alias doesn't exist.

DELETE /{alias}

Returns 204 No Content on success, 404 if alias not found.

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Design Decisions & Assumptions

Persistence - SQLite via JDBC. The database file path is configurable via the DATABASE_PATH environment variable and is volume-mounted in Docker so data survives container restarts.

Alias validation - Aliases must be 2-64 characters, containing only letters, numbers, and hyphens. This mirrors typical URL shortener conventions and avoids characters that are awkward in URLs.

Random alias generation -

Error handling - Invalid input and domain errors are translated into JSON error responses like { "error": "..." }.

Testing - The backend includes service-level tests and can be extended with integration tests. The frontend includes React component tests and service-level API tests.

Frontend - The hosted frontend uses Nginx to proxy /shorten, /urls, and alias requests to the API, so the same Docker setup works without CORS issues.