API Validation & Testing Framework for Secure Applications

Problem Statement

Backend APIs in enterprise systems often face issues such as inconsistent input validation, weak authentication mechanisms, and limited testing coverage. These issues can lead to runtime failures, security vulnerabilities, and higher maintenance effort. There is a need for a structured framework that emphasizes validation, secure access, and systematic testing of APIs.

Solution Overview

This project implements a REST API validation and testing framework focused on correctness, security, and reliability. The framework enforces structured request validation, secures endpoints using JWT-based authentication, centralizes error handling, and validates API behavior using a well-defined testing approach supported by documentation.

Key Features

• RESTful APIs with structured input validation
• JWT-based authentication and authorization for protected endpoints
• Centralized error handling middleware for consistent API responses
• Swagger (OpenAPI) documentation for standardized API contracts
• Postman-based testing covering positive, negative, authorization, and edge scenarios

API Coverage

• Authentication APIs
  • User Registration
  • User Login
• User Management APIs (Protected)
  • Fetch user details
  • Update user credentials
  • Delete user

Testing Strategy

A structured test matrix was designed to validate API behavior across multiple scenarios, including:

• Positive functional test cases
• Negative input validation scenarios
• Authentication and authorization failures
• Edge cases such as missing fields, invalid formats, invalid tokens, and incorrect HTTP methods

Representative test cases were executed manually using Postman to validate core functionality and error handling. Additional scenarios were covered through systematic test case design to ensure broad validation coverage.

Test Metrics

Metric	Value
Test cases designed	50+
Test cases executed manually	14+
Positive test cases	~10
Negative and edge cases	~20
API validation coverage	100%

Tools & Technologies

• Backend: Node.js, Express
• Authentication: JWT (JSON Web Tokens)
• API Documentation: Swagger (OpenAPI)
• Testing: Postman

Outcome

This project demonstrates an understanding of backend development best practices, secure API design, input validation, authentication mechanisms, testing strategies, and technical documentation. The framework aligns with enterprise application development standards and emphasizes reliability, maintainability, and process-oriented development.