Understanding the Importance of API Testing and Why You Should Be Doing It

So what is API testing exactly and why is it important part of your app development process?

First of all, let’s first define what API (Application Programming Interface) is. Put simply, an API is a set of functions, procedures, and other points of access which applications or operating systems make available to programmers that allows it to interact with other software.

It’s somewhat similar to a user interface, but acts as a direct software connection to lower-level functions and operations. APIs are more complex in that usually only trained, knowledgeable programmers deal with them.

With that out of the way, the next question is: what’s API testing?

API testing focuses on the business logic layer of the application, which works on a much deeper level than other types of testing. This is different from GUI testing, which is able to test the look and feel of an application. Instead of using user inputs and outputs, you use software to send calls to the API. You then receive an output and note down the system’s response.

Importance of API Testing

Depending on the testing environment, you’ll most likely be writing your own code to test the API. Programmers should consider using an API testing tool to test, debug and maximise the success of a project.

Why Test an API?

In the development process, API testing allows programmers to find bugs, often before the user interface has been made. Also, API testing lets you make requests that may not be allowed through the UI, which is fundamental in exposing security flaws in the application.

Does that mean there’s no need for UI testing? Not really. Some UI testing will always be needed, especially if you want to verify that certain elements on a page can be interacted with. API tests are still faster, however, and more reliable than UI-based tests.

While some UI testing will always be needed to verify that elements appear on a page and can be interacted with, API tests are much faster and more reliable than UI-based tests. When testing things like adding and removing records from a database, automated UI tests can be time-consuming and repetitive. API tests allow for rapid record manipulation.


Main Advantages of API Testing

Now that you understand what API and API testing is, let’s take a look at the benefits of doing them:

1. Allows you to test the core functionality of the app

API testing helps expose some of the small errors that can potentially become larger problems during UI testing. Core access also lets you test while in development, improving collaboration and communication between different teams.

2. More time effective than GUI testing

API tests work much faster than GUI testing. When automating tests, API test automation requires far less code, thus providing better and faster coverage than automated GUI tests. This is because webpage elements need to be polled in GUI testing, which is why the testing process is considerably slower.

3. It’s language-independent

With API testing, data is exchanged using JSON or XML. As transfer modes, these two are completely language-independent, which lets you choose any core language when doing automated testing services on the application.

4. Can be easily integrated with user interface

Highly integrated tests are possible with API testing. This is a key advantage if you plan to perform functional GUI tests after API testing. As an example, easy integration lets you create new users within the application right before conducting GUI tests.

At the most basic level, the common use for API testing is to expose bugs within the application and to check if the API works on all platforms, such as browsers and operating systems.

API Testing Should Be a Part of Your Development Process

While API testing is considered the challenging part of software testing, it’s important in API development. From a business standpoint, APIs allow for faster innovation. This may mean you get better products that are far ahead from the competition, and monetization is made much easier. To put it simply, using API lets companies penetrate markets they may have never considered, which is why it also pays to invest in proper API testing.

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