Aug 25th, 2024
API Testing: Maximize Benefits and Avoid Pitfalls for Peak Performance
The term “API” (Application Programming Interface) is well-known in modern application development. These days, most applications manage their own internal APIs and rely on at least one external API to handle a multitude of tasks—from user authentication to photo manipulation to maps, payments, and weather. Effective API development also involves rigorous API testing, which ensures that these interfaces work correctly and efficiently across different scenarios and use cases.
This article is focused on APIs not from a consumer standpoint but from the standpoint of developing and maintaining your own API. More and more, companies are exposing their API endpoints and making their internal APIs available to developers. Doing so opens up new revenue opportunities, as you can charge devs for access to your most popular and useful endpoints and functions. But before making your API available to the public, you must ensure it is robust and well-tested.
Even if you don’t make your API publicly available, testing your internal APIs is important for maintaining the stability of your application ecosystem. API testing services is a critical part of this maintenance and ensure that the backend routes of your application are robust, secure, and performant.
What Is API Testing? Why Is It So Important in Today’s Business World?
If the UI is the face of your application, the API is the bones, muscles, and veins. It handles routing user requests to the right parts of your backend, fulfilling those requests, updating databases, returning data to the user, and requesting resources from external APIs. Suffice it to say that if any part of that system breaks, it can affect the whole application.
API testing typically means sending requests to specific endpoints, receiving the endpoint’s response, and comparing it to an expected response. API testing should include negative tests (testing of error handling and failure) as well as positive tests (testing for successful responses.)
UI testing is also important, but typically can’t be done until development of the app or feature is nearly complete. API testing can be performed much earlier on in the development process, and can tell you whether the data in your application is flowing in the right direction.
Types of API Testing
Functional Testing
Checks that an API returns the correct response. It includes unit testing, integration testing and regression testing.
Load Testing
Measures how well an API performs when receiving a high volume of requests.
Performance Testing
Evaluates your API’s real-time performance and simulates traffic spikes using load, stress, and spike testing to prevent unexpected outages.
Runtime and Error Detection Testing
Focuses on error detection and response handling. Monitors the API under actual conditions and checks for leaks and unhandled errors.
Security Testing
Assesses how well an API responds to cyber security threats.
UI Testing
Focuses on improving the functionality and UI/UX design of your application
Fuzz Testing
Sends a large number of random requests to the API to see if it responds with errors, degrades performance, or crashes.
API testing can expose numerous security threats, such as incorrectly assigned user permissions and authentication issues, exposed resources and databases, and data leaks. There is no one type of test that is best for testing APIs. All types are important and expose different weaknesses in the system.
Why Is It Important to Know the Expected Behavior of an API?
It is vital to understand how every part of your application performs. Just as you write UI tests to make sure that a button behaves as expected when you click on it, you must write API tests to make sure that the response the endpoint returns contains the expected type and quantity of data, that the data is correctly formed, and that it is returned in a timely manner.
Without the expectations good API testing establishes, it is impossible to know when an API is performing slowly or improperly.
What Types of Applications Rely Heavily on APIs?
These days, nearly all applications rely on APIs in some form or another—whether your application is dependent on external APIs to handle tasks for you, or your own custom-built endpoints. It is likely that you will need to write tests for both the internal and external routes your application utilizes. Just because an endpoint isn’t managed by your company, doesn’t mean it isn’t your responsibility to make sure the response you’re getting from it is correct.
Bottom Line
API testing is a vital part of the software product development lifecycle, just like UI testing, unit testing, and security testing. If you plan to expose your API’s endpoints and make them publicly available, testing is doubly important—not only to ensure that your API consumers have a good experience, but also to maintain the security of your endpoints and backend.
