An API is the middle man of the systems and layers within an application or software. API testing determines whether the APIs meet the testers expectations of reliability, performance, functionality, and security. There are two are 2 main approaches to online data transmission (read more here):
REST (Representational State Transfer) uses HTTP and is the web standards-based architecture. However, there is no official standard for RESTful Web APIs, unlike SOAP-based web services.
SOAP (Simple Object Access Protocol) is a standard protocol defined by the WS3 for receiving and sending web service requests, etc.
Testing API tips
Know API Requirements. You should know the purpose of API to prepare your test data for input and output. In addition, this part helps you understand the verification approach. For some APIs, you’ll verify the response against the database. For other APIs, you should verify the response against other APIs.
Focus on Small Functional APIs. Login API, get token API, health check API are straightforward APIs with only one or two inputs. These APIs are necessary because they are the gateway to entering further APIs. You’ll ensure the authentication, API servers, and environment work properly by focusing on these simple APIs.
Determine the API Output Status. The most prevalent API output in testing is the response status code. Verifying whether the response code equals 200 to determine whether if they API testing has passed or failed is common for new API testers. However, although it’s not a wrong verification, it doesn’t reflect all test scenarios for API testers. Instead, you should verify whether the code follows global standard classes and if the code is specified in the requirement.
Organize API Endpoints. You may have hundreds of APIs for testing, but you should organize them into categories for the best testing results. APIs in the same categories share the same information, such as path and resource type. As a result, organizing your tests into structures makes your tests reusable.
Use Automation. Capability for API Testing Leveraging automation capability is an excellent way to improve your API testing. It’s easier to run faster, more stable, and more reliable tests when using automation capability.
If you follow these five tips, your API testing experience won't be complicated. It will be faster, more reliable, and more stable.