Backend Developer Interview Test: Node.js

Objective:

Create a backend service using Node.js that manages data between multiple tables with various relationships. The service should authenticate requests using an API key and optionally include an authentication mechanism using Self-Sovereign Identity (SSI) based on the Aries framework.

Requirements:

1. Setup and Configuration:

   • Use Node.js with the NestJS framework.
   • Use Prisma as the ORM.

2. Database Design:

   • Tables:
     1. Users
     2. Groups
     3. Interests
   • Relationships:
     1. Users & Groups: Many-to-many relation.
     2. Users & Interests: One-to-many relation.

3. Endpoints:

   • CRUD operations for each table.
   • Endpoint to add a user to a group.
   • Endpoint to remove a user from a group.
   • Endpoint to retrieve all groups for a specific user.
   • Endpoint to retrieve all interests for a specific user.

4. Authentication:

   • Simple API Key-based authentication:
     • Requests should include an x-api-key header.
     • Store a valid API key in an environment variable.
   • [Bonus] Self-Sovereign Identity (SSI) using the Aries framework:
     • Implement a basic connection protocol.
     • Store DIDs after verification.

5. Testing:

   • Unit tests for GET requests:
     • Retrieve a user.
     • Retrieve groups for a user.
     • Retrieve interests for a user.
   • Integration test to simulate adding a user to a group.

Deliverables:

1. GitHub Repository:

   • Contains the backend code.
   • Includes a README with setup instructions.
   • Features an npm start script for easy testing.

2. Documentation:

   • Endpoint descriptions.
   • Additional assumptions or decisions.

3. API Collection:

   • Postman or equivalent tool setup for testing.

Evaluation Criteria:

1. Code Quality:

   • Clarity and modularity.
   • Error handling.
   • Proper use of async/await.

2. Database Design:

   • Normalization.
   • Relationship setup in Prisma.

3. Authentication:

   • API key authentication implementation.
   • [Bonus] SSI implementation.

4. Testing:

   • Scenario coverage.
   • Test correctness.

5. Bonus:

   • NestJS best practices: modules, decorators, and guards.
   • Provide Postman/Insomnia collections for the API.