Top 30 API Testing Interview Questions and Answers

Given-When-Then is a testing methodology used in API testing to define the preconditions, actions, and expected outcomes of a test case.

• Given: Defines the preconditions or initial state of the system

• When: Defines the actions or events that occur in t...read more

API testing using Postman involves sending requests to an API and validating the response.

• Create a new request in Postman and enter the API endpoint

• Select the appropriate HTTP method (GET, POST, PUT, DELETE, etc.)

• Add headers, parameters, and body if ...read more

There are several status codes available in API testing to indicate the outcome of a request.

• 200 - OK: The request was successful

• 201 - Created: The request was successful and a new resource was created

• 400 - Bad Request: The request was invalid or cou...read more

Variables in Postman are used to store and reuse values throughout requests and scripts.

• Variables can be defined at different scopes such as global, collection, environment, and local.

• Variables can be set using the syntax {{variable_name}}.

• Variables ...read more

Common bugs in API testing include incorrect data formats, authentication issues, and performance problems.

• Incorrect data formats such as missing or incorrect parameters

• Authentication issues like invalid tokens or permissions

• Performance problems such...read more

Pre requisites of API testing include understanding of API documentation, knowledge of HTTP methods, familiarity with testing tools.

• Understanding of API documentation

• Knowledge of HTTP methods (GET, POST, PUT, DELETE)

• Familiarity with testing tools lik...read more

The test plan includes X number of APIs for performance testing.

• Identify all APIs to be tested for performance

• Include both internal and external APIs

• Consider different types of APIs such as REST, SOAP, GraphQL

• Ensure APIs are properly documented in th...read more

We use tools like Postman, SoapUI, and JMeter to test APIs.

• Postman is a popular tool for API testing with features like automated testing, request chaining, and response validation.

• SoapUI is another tool commonly used for testing SOAP and REST APIs, ...read more

CRUD stands for Create, Read, Update, Delete - the four basic functions of persistent storage.

• Create - testing the ability to create new resources through API calls

• Read - testing the ability to retrieve existing resources from the API

• Update - testing...read more

To write a post query in RestAssured, use the given() method to set request parameters and body, then use the post() method to send the request.

• Use given() method to set request parameters and body

• Use post() method to send the request

• Example: given()...read more

To create a payload for API testing, you need to understand the API endpoints, parameters, and expected data formats.

• Identify the API endpoints and the type of request (GET, POST, PUT, DELETE, etc.)

• Understand the parameters required for the API reque...read more

API testing involves testing the various HTTP methods like GET, POST, PUT, DELETE, etc.

• API testing ensures that the API functions correctly and meets the requirements

• Common HTTP methods used in API testing include GET, POST, PUT, DELETE

• Each HTTP meth...read more

API testing with Rest API involves testing the functionality, performance, and security of API endpoints.

• Understand the API documentation to identify endpoints, parameters, and expected responses

• Test different HTTP methods like GET, POST, PUT, DELETE...read more

Performance testing procedures for API involve load testing, stress testing, and scalability testing.

• Conduct load testing to determine how the API performs under normal and peak load conditions.

• Perform stress testing to evaluate the API's stability a...read more

API testing involves checking various response codes to ensure the API functions correctly.

• Test for common response codes like 200 (OK), 400 (Bad Request), 401 (Unauthorized), 404 (Not Found), 500 (Internal Server Error)

• Verify the response code match...read more

RestAssured can be used to automate the Login API by sending HTTP requests and validating responses.

• Use RestAssured library to send HTTP requests to the Login API endpoint

• Include the necessary authentication credentials in the request header or body

• V...read more

API testing in Tosca involves validating the functionality and performance of APIs using Tosca automation tool.

• Create API test cases in Tosca by defining input data, expected output, and assertions

• Execute API test cases using Tosca to validate API re...read more

API testing involves testing different methods of APIs to ensure they function correctly.

• API methods include GET, POST, PUT, DELETE

• GET method is used to retrieve data from the server

• POST method is used to send data to the server

• PUT method is used to ...read more

Playwright is a tool that can be used for API automation testing.

• Playwright can be used to automate API calls and test responses.

• It supports multiple programming languages like JavaScript, Python, and C#.

• Playwright provides a simple and intuitive API...read more

Json path converter is used in API testing to extract data from JSON responses.

• Json path converter is a tool used to extract specific data from JSON responses in API testing.

• It allows testers to easily navigate through complex JSON structures and ret...read more

To re-run a failed API, you can follow these steps

• Identify the reason for the failure by checking error logs or response codes

• Make necessary corrections to the request parameters or code

• Retry the API call using tools like Postman or by updating the c...read more

Validating API through Postman involves sending requests, receiving responses, and verifying data.

• Create a new request in Postman and enter the API endpoint

• Add any required headers, parameters, or body data

• Send the request and check the response stat...read more

Status codes in API testing indicate the outcome of the request made to the API.

• 200 - OK: Request was successful

• 201 - Created: Request resulted in a new resource being created

• 400 - Bad Request: Request was invalid

• 401 - Unauthorized: Request requires ...read more

Important HTTP methods in Postman include GET, POST, PUT, PATCH, and DELETE.

• GET: Used to retrieve data from a server. Example: GET request to fetch user details.

• POST: Used to submit data to a server. Example: POST request to create a new user.

• PUT: Us...read more

API testing verifies the functionality, reliability, and performance of APIs, ensuring they meet expected outcomes.

• API testing focuses on the business logic layer of the software architecture.

• It involves sending requests to the API and validating the...read more

Status codes of REST Assured API responses are used to indicate the outcome of the request.

• Status code 200 - OK: Indicates that the request was successful.

• Status code 201 - Created: Indicates that a new resource was successfully created.

• Status code 4...read more

HTTP methods used in API testing include GET, POST, PUT, DELETE, PATCH, and OPTIONS.

• GET - Used to retrieve data from the server

• POST - Used to submit data to the server

• PUT - Used to update existing data on the server

• DELETE - Used to remove data from t...read more