Getting started with API testing for your startup

API testing is one of the most important parts of the API development lifecycle. Since APIs can be complicated at times especially due to their standards and protocols, some developers might not test every aspect of their APIs leaving them vulnerable to failures when deployed.

API testing is a software testing type that involves checking APIs for performance, security, availability, and functionality issues. It is a process that continues through the life of an API with API monitoring implemented when the API is in use. This shows you how important testing is when it comes to APIs.

Applications derive their value from APIs. They are used in the daily operations of businesses and make it possible for our applications to communicate and share information. A poorly tested API or one that is not tested will most likely fail and affect an entire business instead of affecting just a single application that implements it.

When testing APIs, testers are required to test different parts of the API and its operations. For example, rest API endpoint testing involves testing the locations from which APIs gain access to resources they use when performing their functions.

What Do You Need to Start Testing APIs?

Before you can start testing your APIs, you first need to come up with a testing environment that has all the parameters that the API needs to function. To do this, you will need to configure the server and database to meet the API requirements.

After successfully setting up the test environment, you need to make sure that everything works well to avoid any broken links. You can test this by making a simple API call to see if it behaves as expected.

Once you have established that there are no broken links, you need to test the performance of the API against known input data. You can do this by combining the API tests with your application data.

Finally, you can now start testing your API. However, which types of testing are you going to use?

Types of API Testing

There are different types of API testing that you can use. This does not mean that you can Let us take an example where a developer is using an interface to access WordPress without going through the WordPress installation. This interface is called the WordPress REST API and allows one to create interactive applications and websites.

In such a situation, the developer needs to come up with a test coverage for their WordPress REST API endpoints. The best way to do this is to start from the very beginning making sure that they have tested every aspect of the API. This, in turn, will lead to higher test coverage, making sure that their applications do not break even when they get more complex.

In some situations, developers might argue that their WordPress applications do not deal with any private information or maybe they have written unit tests and therefore do not need to come up with test coverage for the WordPress REST API.

However, since the API provides a read and write interface directly into WordPress, they need to make sure that;

  • Requests are not unintentionally performing write operations on their WordPress applications.
  • Private information is not unintentionally disclosed to unauthorized requests.

Even though developers might verify the security of their endpoints manually when developing their WordPress applications, they need test coverage to test the WordPress REST API to make sure that all security assertions are explicitly made. This is a basic example that shows an API test scenario with WordPress.

The common types of testing include;

  1. Functional Testing: This tests the functionality of the API to make sure that the API does what is expected of it.
  2. Load Testing: This tests if the API has the capability to handle many calls at a time without breaking.
  3. Reliability Testing: It tests the ability of an API to be consistently active while at the same time giving results.
  4. Security Testing: This tests if the API meets its requirements when it comes to permissions, authentication, and access control.
  5. Creativity Testing: This tests the ability of the API to keep working and delivering results even when used in different ways.
  6. Proficiency Testing: It tests the ability of an API to make work easier for developers and increase what they can do with it when developing applications.
  7. Negative Testing: This tests the response of an API when supplied with every known wrong input it could possibly be supplied with.


Finally, when testing your API, you might decide to use either manual or automatic testing. You can even use both. Automated testing is a type of API testing that requires one to use software testing tools. It is preferred when one is performing functional testing, load testing, performance testing, regression testing, and error testing among others.

Manual testing is a type of API testing that requires one to write their own test code to test an API. It can be used when performing tests such as ad-hoc testing, exploratory testing, and usability testing. It is recommended to use automatic testing when performing API tests.