Test Design & Coverage for REST-API
Updated: Jun 14, 2021

Index
Introduction To API’s
API Testing Approach
Useful Checklist To Follow
Common Mistakes To Avoid
Best Practices
Real-Time Example
Prerequisite:
Before diving deeply. First, we have to make sure these three things are there in our hands
API’s functionality documentation
Tool to test an API (Postman/Swagger/Fiddler)
Dedicated environment
API’s functionality documentation helps us to understand the business logic and also the importance of the API. Having this document, we get an idea as to what are the different technologies used for particular SUT(System Under Test).
Tools to test an API One should have knowledge of the tool and what varieties of features it offers that makes it the perfect tool for testing the API. Choose the tool wisely based on your comfort (Personally I recommend Postman).
Dedicated Environment This is important as the changes/issues don’t affect the QA environment and the teams working on it.
Introduction to API’s

An API stands for Application Programming Interface.
An API will simply state the set of rules for the communication to happen between the systems/services.
API Testing
The purpose of API Testing is to check the functionality, reliability, performance, and security of application programming interfaces.
It mainly concentrates on the business logic layer. API testing helps us to find more vulnerabilities that can be missed in the functional testing (UI level).
Why do we have vulnerabilities in API?
Flaws in the Business logic
No A to Z validation
Unhandled Exceptions
Not filtering the user input
API testing approach

API Testing Approach is a predefined strategy or a method that the QA team will perform.
This helps to better understand the functionalities, testing techniques, input parameters, and the execution of test cases and also will help testers for better coverage.
The following points will help tester for API testing approach
Understanding the business logic and functionalities of each and every API
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