API Testing – An engrossing and Comprehensive Guide for All

API Testing – An Out-and-out Overview

As we advance, our technology allies have also evolved to address the complexities of our lives and work. This has led to developing multiple layers of intelligence and internal and external integrations of software and application. To make it possible, APIs or Application Programming Interface have come to the rescue, which makes API testing of software critical.

What are API and API testing?

Let’s get our concepts clear and start with the very basics. Application Programming Interface acts as the intermediary layer between database layers and the UI (user interface). This enables communication and exchange of data between the various layers and software applications. In the words of Wikipedia, API testing is defined as a kind of software testing that encompasses testing the APIs, both directly and as a part of the integral software testing procedure. It helps in determining if all the functional expectations and requirements, reliability, security, and performance are at par. 

While direct API testing validates the attributes of the software’s innate capabilities, when done as a part of the integrated testing, it corroborates the logic associated with the architecture of software within a short span. 

Unlike other testings, in API testings, you do not use the standard inputs, rather send calls or messages to the API. This is to check and record the responses and if they meet the output goals. It is inherently different from GUI tests and does not centralize on the UI but the functionality and effectiveness of the API layers and the business logic in the layers of the software application. 

Testing Categories

Let’s look at the different types of API testings for a better understanding:

• Functional testing – Check the specific functional parameters and outcomes by testing broader scenarios.
• Validation testing – It is done during the final stage. It has a significant role to play along the development process. It validates the product, efficacy, and behavior aspects to warranty the accuracy of the development process.
• UI testing – Test the UI compatibility for the API layers and other integral parts. Unlike the conventional API testings, UI testing focuses on the interface layers associated with the API. It offers a sketch of the usability, health, and proficiency of both the front and back ends of the software.
• Security testing – It validates various security parameters. It includes authentication, access control, encryption, and user management rights. This further ensures the software is safe against external threats.
• Load testing – It verifies if the API-enabled application functions efficiently under all circumstances and pressure levels. Also Read https://www.testgrid.io/blog/load-testing-a-brief-guide/ to know more about Load Testing
• Penetration testing – In this test process users with limited knowhow of API networks to evaluate the threat vectors and vulnerabilities from an external perspective.
• Fuzz testing – Test random parameters and inputs to check the optimum limits of the API under the worst-case scenario. Also Read https://www.testgrid.io/blog/everything-about-fuzz-testing/ to know more about Fuzz Testing
• Runtime & error detection testing – Test the functionality and defects while in action to validate its flawlessness during the actual runtime.

Where is it Performed?

Now that we have a clear overview of what is API testing and the different classifications attached. So, let us look at where this can be performed. Typically, software or application has three vital layers, namely, the user interface (UI) layer, the database layer, and the business layer. Of these, the business layer is unequivocally the most crucial layer. Through API testings, you check the logic processing in the business layer, covering all the undertakings between the UI and database layers in the application.

Pre-requisites of API Testing

API testing comes with a set of preconditions for optimum performance and the best results. Let us quickly glance at the checklist now.

• Evaluation of the team’s proficiency – Check how well-versed your team is when it comes to this testing and the related architecture. You should understand how well they comprehend the API and automation tools involved. Consider involving an external QA team in case your in-house team falls short of knowledge in the specific areas.
• Setting up an API Testing environment – Configure the server and database to fit the testing requirements. 
• Define the test plan – API testing needs a predefined test plan. It helps to get a clear vision of what should be tested and what outcome should be expected.
• Choose the right API and automation tools – Selecting the testing tools is very important when it comes to testing. Choose the most suitable API tools, preferably automation tools, for a faster and more accurate testing experience.
• Strategize the bug tracking and execution process – Create a well-defined strategy to execute the testing, detection, monitoring, reporting, and fixing the errors in the API framework.
• Stipulate the API output status – Define the output results you are looking for as an outcome of the API test. This helps to verify the end results with the same.

Challenges with this Testing

Every type of software testing comes with its own share of challenges, and API testing no exception. Here are a few common challenges to note:

• Setting up API testing – The prepping of this framework is of utmost importance. Often the first knot coming in the way of the testers and developers. You can overcome this by taking time to understand the prerequisites (given above for the benefit of the readers) and designing the framework accordingly.
• Updating the schema of API testing – Update data formatting or the schema frequently. It helps to maintain relativity throughout the testing process. The challenge is that with every iteration in the program, additional parameters come into play.
• Testing the parameters – It is necessary to test all the related parameters passing through the database and data requests. It is done across all possible combinations and specific configurations. 
• Validating the parameters – Validating a number of parameters is a daunting task. Because it requires verifying each numerical data and sequence.
• Sequencing API calls – API calls often need to follow a specific route or sequence. Creating the sequence map can be a hurdle to the testers and developers.
• Tracking system integrations – Keeping a track of all the system integrations is a tedious task. It can often be intimidating to the team.

APIs form the bridge between different layers and integrations within software or application and API testing can ensure the flawlessness and fluidity of the API. Hence, it is an indispensable test parameter for multi-layered and integrative software and applications.