Users expect to be able to use apps across devices and browsers. As a result, you must conduct thorough different API testing types to understand how well it works and whether it can perform its primary functions. Some testers need to pay more attention to this aspect, and as a result, we see many applications of poor quality. Today we want to explain what types of API testing are and why they are so important.

Functional API tests

This type of API testing aims to understand whether this part of the program code can perform the functions for which it was created. It can be verified by positive and negative testing. To do this, the specialist enters correct and incorrect ones and sees how the system reacts to them. If it fails on the correct data, it does not work well even in ideal conditions, which means that blunders have been made.

There are the following types of functional tests:

• Unit testing. It allows you to understand how well each part of the code performs the tasks for which it was created. It is worth conducting this type of test after completing each module.
• Runtime error detection. It allows you to identify the slightest defects in the process of your software. Typically, such tests are run in parallel with unit testing.
• API documentation testing. When you create software, the first thing you do is develop a specification. Subsequently, all the actions that you performed with the code are documented. This testing allows you to check the correctness of filling out such documents and how much what is written on paper corresponds to reality.

The above types of testing allow you to understand how your software meets the goals for which it was created and whether it can meet the needs of customers.

API performance tests

Common API testing is unimaginable without this type of testing that covers quite a lot of different processes. When your software is first released, it will be used by a limited number of users, but gradually their number will grow quite significantly. You may have seen online stores that take a long time to load during sales, or programs that can’t handle the load after adding new modules.

To check the performance, use the following types of tests:

• Load testing. It determines how the application works when many people use it simultaneously, how long it takes to open a new page, how the central systems work, and much more.
• Soak testing. It allows you to detect system instability, such as a memory leak. Such tests take a lot of time because you need to see how the system behaves in dynamics.
• Stress testing. It allows you to understand how your software will behave in stressful situations, such as hacking attempts or power or internet outages.
• Spike testing. Specialists check how the software reacts to a sharp increase and decrease in users. It allows you to understand how quickly the system can stabilize.
• Scalability. As your business grows, you will need to add new features or enter new markets. Scaling testing is used to test how up-to-date your software is.

Different types are used at various stages of software development. Your project will work stably under other loads if you do everything consistently.

API security tests

Your software will store a lot of information about your customers, and this data mustn’t fall into the hands of intruders. It is of utmost importance if you accept payments, as scammers can hack into your system and access critical information.

To prevent this from happening, you need to use the type API tests. It includes:

• Security testing. It allows you to check how well all the data is encrypted, how easy it is to access it, how well the authorization settings are configured, and much more.
• Permeability test. It allows you to identify vulnerabilities in your program code that attackers can use for a hacker attack and how the system reacts to outside interference.
• Fuzz testing. It is usually used in the last stages of development. Specialists are explicitly trying to disable the system and see how it will react to a large amount of incorrect data.

There are many examples where security issues have led to the destruction of a brand. So, if you want customers to trust you, you need to take care of security.

API integration and reliability tests

You need to test the API interface to see how well it integrates between internal and third-party services. It can be done through integration and reliability testing. It allows an understanding of how well your product can communicate with other APIs and whether it will cause errors. Likewise, it also lets you know whether connecting to other APIs will cause a system shutdown.

We can distinguish the following main types of integration and reliability testing:

• Integration testing. This is testing various modules and identifying various defects that can occur when these components are integrated and must interact with each other.
• Reliability testing. It allows you to understand whether the software can perform uptime in a particular environment for a certain period of time. Experts strive to understand if there are any errors in your program code that can affect the level of reliability.
• Web UI testing. It involves testing the visuals that the user will encounter to make sure they meet performance criteria. In addition, web interface tests ensure that there are no bugs in the functions.
• Interoperability testing. It helps you understand if your product can interact with other software components and systems.

The above types of testing for API interface allow you to understand how comfortable it will be for people to use your product, whether various failures will occur during operation, and how reliable your software is.

WS Compliance

There are many specifications that your software must comply with. This kind of test is aimed at helping you understand how your project matches them. It will not only raise the prestige of your company, but will also convince your investors that you are interested in creating a good product.

API testing will help you to ensure that the APIs that your organization is developing or using are working correctly and efficiently. It will identify problems early in the development process, contributing to a greater reliability. Don’t forget that API testing should be emerged with the overall software testing process, as APIs often serve as the interface between different systems and play a key role in the integration of those systems.