Fri Apr 22, 2022

What is API Testing and Why Should You Do It?

A phone and a laptop showing code

If you’re reading this, then I’m going to assume you already know what an API is. But, for the sake of those who may not know, I’ll touch on the fundamentals a bit.

What Is an API (Application Programming Interface)?

An API is a software interface that allows data exchange and communication between two separate software applications. One system executes the API, while another performs its functions and subroutines. The API specifies the data formats, methods, and requests that can be made between two software systems.

APIs are the reason why you can log in to your Twitter account using your Google account credentials. What happens, in very simple terms, is that Twitter sends a request to Google via APIs to fetch your data and voila, you’re in!

What Is API Testing?

API testing is the practice of validating the integrity and functionality of APIs by sending requests across system software and evaluating system responses. In API testing special software is used to send calls to the API eing tested while the responses are noted and analyzed.

API testing works on the business logic layer of a codebase, so any anomalies detected could lead to astronomical effects One could say that APIs make up the background framework of the internet as we know it today. This is why API tests are invaluable.

Why Should You Test APIs?

API testing is crucial now more than ever because APIs serve as the primary link to business logic. Perhaps, the most important reason for API testing is that as a system scales, changes are made across the codebase. API regression tests can help to detect whether a system upgrade results in a break in API interfaces.

Such a break could have catastrophic results for web apps that rely on those APIs.

On the other hand, API observability like what we do at APItoolkit can help you detect breaks in API interfaces that your web app relies on. For more context, here’s a list of the types of bugs that can be detected by API tests

  • Duplicate functionality
  • Missing Functionality
  • Incorrect structuring of Response Data (JSON or XML)
  • Problems in calling and getting a response from an API.
  • Security Issues
  • Incorrect handling of valid argument values
  • Performance lapses.

API Testing Tools

API testing can be done with a variety of automated tools.

  • Rapid API testing: Over 1 million developers and 10,000 APIs are available on Rapid API testing. It’s an API testing solution for managing complex API tests throughout the development process. You can run tests for any type of API (including REST, SOAP, and GraphQL).
    Rapid API Testing
  • SOAPUI test: Mainly used for REST, SOAP, and other mainstream API and IoT systems.
  • Postman testing: Commonly used for REST APIs
    Postman testing
  • Parasoft testing: It’s a paid tool. It’s used for comprehensive API testing.
    Parasoft testing

What Are API Test Cases Based on?

QA teams are usually in charge of API testing. It’s normal to see them follow a predefined strategy to conduct the API testing after the build is ready. This testing may not necessarily include the source code. The API testing approach helps to better understand the functionalities, security and testing techniques, input parameters, and the execution of test cases.

API test cases are based on the following considerations

  • Failure to return a value: This is an event in which there is no return value when an API is called. Trigger some other API/event/interrupt: Events and interrupt listeners should be tracked when an API output triggers some events.

  • Return value based on input condition: This is pretty straightforward. Input is made and the results are authenticated.

  • Update data structure: Changing data structures will have some effect on the system, which should be authenticated Modify certain resources: API calls that modify resources should be checked by accessing the corresponding resources

Key Takeaways

  • APIs are software interfaces that allow data exchange and interaction between two different software applications.

  • The purpose of API testing is to validate the integrity and functionality of APIs by sending requests across various systems and evaluating system responses.

  • When approaching API testing, assess which APIs can enable important customer-facing applications/solutions and which can provide a solid technical foundation.

  • API testing should be prioritized based on company strategy, business and modernization impact, as well as ability to execute.

  • Develop API testing standards for your organization and train developers on prioritization.

Final Thoughts on API Testing

API testing represents the most fundamental measure in maintaining the seamless operation of application systems.

When APIs are not tested thoroughly, it leads to problems in the API and calling applications. Suffice it to say that API testing is indispensable in software engineering. A break in an API calling system for a few seconds could have huge financial consequences.

API toolkit essentially provides API observability and testing as a service. We augment your QA team, to detect issues automatically and in real-time.