API Testing Tutorial for Beginners

An important yet difficult aspect of software development is API testing since it incorporates a lot of elements that we just do not come across in the other parts of the development process. In most situations, just the minimum requirements that the API should possess are tested, but, in reality, you are responsible for testing everything to ensure that it is functional as well as all of the security features. However, having a trustworthy API without glitches can have profound effects on your product. Before we get into all the details of API testing, let’s get more of an idea of what this process is and later on we will get to know some of the tools used to get the job done.   

What is API Testing? 

In layman’s terms, API testing is making sure that there is nothing wrong with the API which would prevent it from functioning the way that it is supposed to. Even though the API testing process is expensive and time-consuming, putting out a product that has bugs in the API is dangerous and all of the security breaches could cost you even more. While there are many business and technical reasons for making sure that everything is alright with your API. Below we have listed the five main reasons why companies decide to go ahead with this process:  

1. Ensure proper functionality 
2. Ensuring it can withstand the workload 
3. Account for everything that could go wrong on the user’s end 
4. Verifying that it works across all devices 
5. Breaches can be costly 

Whenever you invest in the API testing process, it will result in a much better final product. If you know that all the data goes through the API, this makes your testing and compliance process much easier, because there is a single interface. By making sure that all the necessary business rules are being followed on the API level enables a much more comprehensive user experience testing as soon as the user interface is available without having to focus on each individual business rule at the concluding stages of the project.  

How to Test API 

Testing the API of your software business solution begins with setting up the necessary environment with the correct testing rules around your API in order to make sure that exactly the features that you would like to test will be targeted. This will require adjusting the database and the server for everything that the app requires to function. When the test environment is up and running, do an API call to verify that everything works properly prior to beginning rigorous testing. Now you can start combining data obtained from the app with the API tests to ensure functionality across all known input possibilities. Keep in mind, that there are lots of API tests out there:  

• Functionality testing – validating that everything is functioning properly  
• Reliability testing – validates that the API produces the same results every single time 
• Load testing – validates the API’s ability to handle the necessary volumes of calls 
• Negative testing – thinking of all possible wrong user inputs testing them all 

One of the most frequently used API testing software is REST-Assured, which is great when you are using Java. It can be used to test your services that are HTTP based. It was created specifically for testing purposes and can be integrated with any Java-based automation framework that you may already have. Another great tool is called Postman. It is very useful for some quick API testing without having to always think about the overhead other options might have. Its interface is much richer than most other REST clients thus making it very easy to use. Therefore, if your team needs to test APIs and also have something handy that allows them to automate certain explanatory API testing processes, this is certainly a great choice for you.   

Also, it is important to remember that there is no such thing as a perfect tool. Each one will have its own unique requirements and pretty much all of them work very well, but it will come down to your team’s specific requirements.   

We hope that this API testing tutorial has shown you that even though testing APIs is complicated, it is certainly a manageable process and more importantly it is very significant. If the testing process wasn’t done properly, it can create a lot of problems in both the API application and when calling application. As soon as you API has been tested and you have verified that it works properly, get all of your API documentation in order so that if someone would like to integrate with your platform, they will know what they can expect from each feature of your application. If you have a great API, you want to showcase it to other developers so that they can integrate, but without the necessary documentation, it will be impossible for anybody to find out exactly what they can do with your API. When you provide bad API documentation, it really slows down the development process, which is why it is very important that you write out all of the descriptions for all the functions, but also for the data types as well.  

API is at the very core of the apps and websites that we use today and if your app has an unreliable API it could really discourage a lot of users from accessing your app.