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API Testing: Quick Guide for Software Testers

API is a common term these days, you must have heard this term. APIs have made coding faster for many developers. Also, it provides a window of using a single code in more than one application to perform similar tasks. The APIs are also used by the developers to use the functionality of one solution within another solution by integrating that API in the existing code. The integrated API will bestow all features of another solution within your system. For an instance, you can use an SMS solution of a third party business provider within your call center or CRM system. The end user will never get to know that he is using two different applications. This is the power of the API.

API Definition

We understood what the API is! Now it is time to define it technically.  An API aka Application Programming Interface creates a bridge between two different applications or software to let them interact with each other to meet certain goals.

API Testing

API Testing is a process of quality assurance and testing the API to be used in software by applying a whole range of functional and nonfunctional tests on it.

The Software testers thoroughly test the APIs to check various factors such as,

  • Accuracy
  • Efficiency
  • Response Rate
  • Security
  • And more

The API testing expert will create different test cases as we all as an API test code to test and write actual and expected results.

Major Reasons to Perform API Testing

Using an API means making it an integral part of your software. Its failure and success define your failure and success. That’s why it is important to thoroughly test it for the following criteria:

  • Flawless operations
  • Compatibility
  • Performance and Response
  • Security
  • Usability

A solution may work great as a standalone application, but it may react abnormally when we inject an API in it. Thus, it is important to assure the quality performance of the solution with an API. To save time, it is necessary to test APIs before integrating it. Of course, testing the solution with APIs is important as well.

Steps to effectively test an API:

The API should go through all different test cases and types of tests like any software. However, there are a few best practices, which can be applied during API testing to save time. Below is step-wise process to perform effective API testing:

  1. Test APIs under normal and abnormal conditions with expected and unexpected inputs and API calls to see how it behaves. This will help in detecting bugs, if there are any, in early stage. This can be done with automated testing tools to test multiple inputs in less time.
  2. If API passes the first stage, then perform stress testing to see how the API reacts in case of excessive load.
  3. Third step is to see the behavior of API in case of failure. See how APIs react in case of failure. Does it give the required information to reveal the cause of failure to end user or not? Does it handle failure abruptly? All this helps in maintaining in great user experience.
  4. Last, but not the least, is security testing. You need to assure the API is not stealing any private or sensitive data from the software.

These are the top 4 steps, each QA testing engineer must follow to assure flawless performance of the API.

We, QA Mentor, have a team of experienced API testing engineers. If you are looking for help from experts for API testing, get in touch!


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