Selenium WebDriver
API Testing Introduction & Postman Basics
Master API testing fundamentals, HTTP methods, Postman basics, and API validation techniques for comprehensive automation testing.
What is API?
API - Application Programming Interface
Key Definitions
- • API stands for Application Programming Interface
- • API is used for communication between 2 or more software components [Front End and Backend Database]
- • API is used to exchange test data between 2 or more software components
- • Everyday we use applications like Facebook, WhatsApp, YouTube, Amazon, mobile phones - we use API
API Communication Flow
Understanding how Browser (Frontend), API (Middleware), and Server (Backend Database) communicate with each other
What is API Testing?
API Testing Fundamentals
Core Concepts
- • API testing is a type of software testing
- • Inside API testing we focus on business logic of the functionality
- • API lacks UI (user interface) - no user interface is present
- • We validate business logic of functionality with the help of different HTTP Requests
🎯 Key Focus Area
Business Logic Testing: Since APIs don't have UI, we concentrate on testing the core business rules, data processing, and functionality logic through various HTTP request methods.
HTTP Request Methods
5 Different Types of HTTP Requests
1. POST Request
Create new data
2. PUT Request
Update entire resource
3. PATCH Request
Partial update
4. GET Request
Retrieve data
5. DELETE Request
Remove data
GET Request - Detailed Explanation
GET Request Purpose
- • GET Request is used to retrieve entity from the server
- OR
- • GET Request used to search user information or open user information as per condition
GET Request Examples
Example URLs and Use Cases
1Search all Employee→ GET Request
http://localhost:3000/employees
2Search Employee as per employee ID→ GET Request with Path Parameter
http://localhost:3000/employees/{id}
3Search Employee as per employee first Name→ GET Request with Query Parameter
http://localhost:3000/employees?firstName='Anuja'
4Search Employee as per employee dept name→ GET Request with Query Parameter
http://localhost:3000/employees?deptName='IT'
📋 URL Source
To hit GET Request we need URL → Swagger Documentation
GET Request Validation Points
Once we hit the Request we verify different things:
1. Status Code / Response Code
Expected: 200
2. Status Line
Expected: 200 OK
3. Response Time or Latency
Performance validation
4. Response Payload or Body
Employee info in JSON or XML Format
5. Response Header
Header validation
6. Response Cookies
Cookie validation
DELETE Request - Detailed Explanation
DELETE Request Purpose & URL
DELETE Request URL Example
http://localhost:3000/employees/{id}
DELETE Request Validation Points
1. Status Code / Response Code
Expected: 204
2. Status Line
Expected: 204 No Content
3. Response Time or Latency
Performance check
4. Response Header
Header validation
5. Response Cookies
Cookie validation
Postman Tool for API Testing
🚀 Postman - API Testing Tool
Postman is a popular API testing tool that allows you to:
- • Send HTTP requests (GET, POST, PUT, DELETE, PATCH)
- • Validate API responses and status codes
- • Test API endpoints with different parameters
- • Automate API testing with collections and scripts
- • Monitor API performance and response times
📚 Learning Path
In upcoming lessons, we'll dive deep into Postman usage, API automation, and advanced API testing techniques with practical examples.
Sample Employee Database (JSON)
Employee API Test Data
This is sample JSON data that represents employee information used for API testing examples:
{
"employees": [
{
"firstname": "anuja",
"lastname": "patil",
"city": "pune",
"mobilenumber": 909090,
"email": "anuja1@gmail.com",
"id": "1"
},
{
"firstname": "Suraj",
"lastname": "Yadav",
"city": "Delhi",
"mobilenumber": 7777,
"email": "suraj1@gmail.com",
"id": "3"
}
]
}JSON Structure Explanation:
- • employees: Array containing employee objects
- • firstname, lastname: Employee name fields
- • city: Employee location
- • mobilenumber: Contact number (numeric)
- • email: Employee email address
- • id: Unique employee identifier
📄 JSON Server Setup Documentation
JSON Server Setup Guide
Complete documentation for setting up JSON Server for API testing practice. This PDF contains step-by-step instructions for creating a local API server.
JSON Server Setup GuideOpen in new tab
Key Takeaways
🔗 API Fundamentals
- • API enables communication between software components
- • Used for data exchange between frontend and backend
- • Essential for modern application architecture
- • Present in everyday applications we use
🧪 API Testing Focus
- • Tests business logic without UI dependency
- • Validates data processing and functionality
- • Focuses on backend system behavior
- • Uses HTTP requests for validation
📡 HTTP Methods
- • GET: Retrieve data (Status: 200 OK)
- • POST: Create new data
- • PUT: Update entire resource
- • DELETE: Remove data (Status: 204 No Content)
- • PATCH: Partial updates
✅ Validation Points
- • Status codes and status lines
- • Response time and latency
- • Response payload (JSON/XML)
- • Headers and cookies validation