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Software Engineering Fundamentals questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master software engineering fundamentals interviews.

What difficulty level is this interview question?

This is a medium difficulty Software Engineering Fundamentals question, commonly asked during Technical Screen rounds at League.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at League during technical interviews.

Design matrix-operations HTTP service and test strategy

Quick Overview

This question evaluates system and API design, input validation, error handling, project architecture, and test strategy for backend services, assessing practical software engineering competencies such as modularity, clarity, and testability.

You are given a take-home assignment to build a small backend server. The goal is not algorithmic difficulty but demonstrating solid software engineering practices, project structure, and test design.

Design an HTTP service that exposes several APIs to perform operations on 2D matrices of integers. At minimum, support:

Matrix addition
Matrix subtraction
Matrix transpose
Horizontal flip (reverse columns)
Vertical flip (reverse rows)

Assume:

Clients send requests over HTTP using JSON.
A matrix is represented as a 2D JSON array of integers, e.g. [[1, 2], [3, 4]] .
For binary operations (like addition), the client sends two matrices in the request.
The service should validate input (e.g., shape compatibility for addition) and return clear error responses for invalid input.
Performance is not the primary concern; correctness, clarity, and testability are.

Describe in detail:

Overall architecture and project structure for this server (layers, modules, packages, etc.).
API design : the endpoints you would expose, HTTP methods, and example request/response payloads for each operation.
Validation and error handling : how you handle malformed JSON, non-rectangular matrices, dimension mismatches, and unexpected server errors.
Testing strategy : what unit tests, integration tests, and possibly end-to-end tests you would write, and how you would organize them.
Any additional engineering considerations you think are important (e.g., logging, configuration, extensibility for adding new matrix operations later).

Quick Overview

Design an HTTP service that exposes several APIs to perform operations on 2D matrices of integers. At minimum, support:

Matrix addition
Matrix subtraction
Matrix transpose
Horizontal flip (reverse columns)
Vertical flip (reverse rows)

Assume:

Clients send requests over HTTP using JSON.
A matrix is represented as a 2D JSON array of integers, e.g. [[1, 2], [3, 4]] .
For binary operations (like addition), the client sends two matrices in the request.
The service should validate input (e.g., shape compatibility for addition) and return clear error responses for invalid input.
Performance is not the primary concern; correctness, clarity, and testability are.

Describe in detail:

Overall architecture and project structure for this server (layers, modules, packages, etc.).
API design : the endpoints you would expose, HTTP methods, and example request/response payloads for each operation.
Validation and error handling : how you handle malformed JSON, non-rectangular matrices, dimension mismatches, and unexpected server errors.
Testing strategy : what unit tests, integration tests, and possibly end-to-end tests you would write, and how you would organize them.
Any additional engineering considerations you think are important (e.g., logging, configuration, extensibility for adding new matrix operations later).

Design matrix-operations HTTP service and test strategy

Quick Overview

Solution

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Design matrix-operations HTTP service and test strategy

Quick Overview

Solution

Submit Your Answer