Skip to main content

API Testing

By Srinesh Nisala

Pre-requisites​

[!NOTE] It's important to understand the basics of HTTP and RESTful than how to use a specific tool.

Website vs Web Service​

  • Website: Deliver human-consumable content via a browser
    • Interaction is user-driven (clicks, scrolls, inputs)
    • Technologies: HTML, CSS, JavaScript
  • Web Service: Enable machine-to-machine communication over the web
    • Data is transferred in structured formats (e.g., JSON/XML)
    • Technologies: REST, SOAP, GraphQL

Exercise 1: HTTP Request and Response​

  • Open a new browser tab
  • Open the network tab in the developer tools
  • Visit a website (e.g., https://www.google.com)
  • Observe the first network requests made by the browser

Http Request Response

Exercise 2: Calling a web service using HTTP​

Exercise 3: Using other tools to call a web service​

  • Open network tab in the developer tools
  • Go to https://jsonplaceholder.typicode.com/posts/1
  • Observe the response data
  • Use xh to make the same request xh https://jsonplaceholder.typicode.com/posts/1
  • Use Bruno to make the same request
    • Create a new collection
    • Create a new request
    • Set the method to GET
    • Set the URL to https://jsonplaceholder.typicode.com/posts/1
    • Click on Send

Exercise 4: Using Bruno to make a POST request​

  • Create a new request
  • Set the method to POST
  • Set the URL to https://jsonplaceholder.typicode.com/posts
  • In the body tab, select JSON and enter the following JSON data:
{
  "title": "foo",
  "body": "bar",
  "userId": 1
}
  • Click on Send

Exercise 5: Using REST Assured to make a GET/POST request​

  • Open https://github.com/s1n7ax/lecture-api-testing in codespace
  • Send a request to https://jsonplaceholder.typicode.com/posts/1 and get post
  • Add validations to check if the response status code is 200 OK
  • Add validations to check if the response body contains the correct title
  • Send a POST request to https://jsonplaceholder.typicode.com/posts and create a new post
  • Add validations to check if the response status code is 201 Created
  • Add validations to check if the response body contains the correct title and body

HTTP vs RESTful​

  • HTTP (Hypertext Transfer Protocol, 1996): source
    • Protocol for transferring data over the web
  • RESTful (Representational State Transfer, 2000): source
    • An architectural style (not a protocol!) for designing networked applications

HTTP Methods​

  • GET: Retrieve data from the server
  • POST: Send data to the server to create a new resource
  • PUT: Update an existing resource on the server
  • DELETE: Remove a resource from the server
  • PATCH: Partially update an existing resource on the server
  • OPTIONS: Retrieve the allowed HTTP methods for a resource

HTTP Request/Response Data​

  • Request: Client sends a request to the server
    • Method (GET, POST, PUT, DELETE, etc.)
    • URL (Uniform Resource Locator)
    • Headers (Metadata about the request)
    • Body (Data sent with the request, optional)
  • Response: Server sends a response back to the client
    • Status Code (Indicates the result of the request)
    • Headers (Metadata about the response)
    • Body (Data returned by the server, optional)

HTTP Status Codes​

  • 1xx: Informational
  • 2xx: Success
    • 200 OK: Request succeeded
    • 201 Created: Resource created successfully
    • 204 No Content: Request succeeded, no content to return
  • 3xx: Redirection
    • 301 Moved Permanently: Resource moved to a new URL
    • 302 Found: Resource temporarily moved
  • 4xx: Client Error
    • 400 Bad Request: Invalid request syntax
    • 401 Unauthorized: Authentication required
    • 404 Not Found: Resource not found
  • 5xx: Server Error
    • 500 Internal Server Error: Generic server error
    • 502 Bad Gateway: Invalid response from upstream server
    • 503 Service Unavailable: Service temporarily unavailable
  • 504 Gateway Timeout: Upstream server did not respond in time