API Testing: What Should be Tested?

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February 12, 2021 Web development

In an application, the API layer acts as a very essential part of its functionalities. It connects the server to the client providing services that add value to the application and driving almost all processes in a business.

This means that failure by a single API not only affects a single process but all processes designed around the API. This has the potential to bring down a business and cause irreparable damage.

To show you how testing is important in companies, Google introduced a feature that allows gamers to test games on Play Store without installing them. Even though this might be a simple feature compared to testing APIs, it is important for users of any application to be able to test them before their actual use.

Furthermore, if one creates a solid testing strategy for their APIs, they are most likely going to get higher reliability from their applications. Chances are that they will be able to iron out any current and future errors that might affect the operations of the API.

If you are working on an API, you might be wondering about the best way to conduct your tests, what to test and what to use when testing. To start with, you can have a look at some of the best API testing tools here. These tools will make testing easier and straightforward. Make sure you get a tool that best suits your API.

Before you start testing an API, it is important to come up with a testing strategy and work on what to test.

Testing Strategy

The testing strategy involves describing all the requirements that will be needed through the testing process. At a later stage, this description can be used to come up with a test plan detailed enough to meet all test requirements.

Further, make sure that you plan about functional testing when working on your testing strategy. This is used to determine if the functions of the API are met. It also;

Tests if the implementation of an API works as required.
Tests if the implementation meets all the requirements of the specification document.
Prevents confusion that might be brought by releases and code merges.

What should you Test?

Now that you have worked on your testing strategy and even chosen a tool to use for the testing, you need to determine what you need to test. This is where most developers and testers go wrong. You need to come up with test cases that make sure that every single functionality of the API is checked.

The first thing to do is to add test actions to your tests. This comprises the individual things that each test needs to do. The most common actions you need to consider include;

Checking response headers. Server headers affect both the performance and the security of an API.
Checking HTTP status codes.
Checking the state of an application. This is done manually. It can also be done for easy to inspect interfaces.
API’s response load. This involves checking correct types, names, and values. It also checks if the JSON body is valid.
Checking basic performance. The fact that an operation succeeded is not enough to assume successful completion. Some operations might take more time than expected, meaning that the test has failed.

Finally, it is important to have both positive and negative tests for your API. Positive testing involves the use of valid data sets as the input when testing an API. It is used to check if the API will function as expected when valid data sets are used.

Negative testing involves the use of improper or invalid data sets as the input when testing an API. This type of testing is used to check the performance of the API with unwanted or negative data input. Negative testing is important when making sure that an API will function well even with invalid or negative data input.

Conclusion

API testing should not be the last time you check for issues that might affect the functionality of an API. As discussed earlier, failure by APIs can affect the entire operations of a business. Developers also need to employ API monitoring that checks APIs for availability, performance, and functional correctness.