It would hardly be an exaggeration to say that APIs (Application Programming Interfaces) are one of the cornerstones of modern-day software development. They serve as a crucial component of various software products. They connect different systems and program layers and help transfer data between them.
The majority of both enterprise and consumer applications today rely on APIs to power a variety of processes. This is why effectively and diligently testing your APIs before launching the product is increasingly important. It is also why neglecting your testing can have serious long-term consequences.
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What is API testing?
API testing is a type of software testing. It uses several quality assurance actions to check if your APIs are meet specific functionality, performance, security, and reliability criteria.
API tests focus mainly on a software product’s business logic. Because APIs lack a GUI (graphical user interface), API testing happens at the message layer. Some of the quality actions executed during tests include sending calls to the API, getting output, and analyzing the system response to meet multiple requirements, such as an absence of error codes, accurate data transfers, timely data updates, etc.
Why is API testing important?
Because APIs serve as the main interface powering application logic, API testing is a crucial component of automated testing, which is quickly replacing manual software QA.
Here are several main reasons why API testing is getting increasingly important today.
Necessary to ensure proper application logic
Modern applications are getting more complex. In order to meet growing consumer needs, apps have to include more and more functions, many of which require APIs. As a result, thorough testing is required to make sure all components of the application’s logic are functioning properly.
A Better alternative to GUI tests
API testing is an ideal match for agile software development practices. This is because GUI tests are slow and difficult to combine with the short release cycles and frequent changes expected today. Developers often prefer API tests to GUI tests because APIs don’t rely on the UI (user interface) and changes in it.
Security threat prevention
The API layer of the application can also be quite vulnerable to hacker attacks. This is another reason why API security testing is getting more important, especially for enterprise applications.
Types of API testing
There are multiple ways you can approach API testing. They are most commonly divided into the following types.
Functional testing assesses functions in the codebase by running a number of specific scenarios to make sure APIs perform in line with key parameters. In addition, Functional API testing uses Unit tests (testing the functionality of individual processes) to divide the process into separate building blocks.
Performance testing assesses the performance of APIs by creating different types of API calls. Here are some of the main performance-related API tests:
Load testing validates the performance of APIs under load. It is typically done after the completion of a specific app process or the whole codebase. Load testing often relies on the scenarios from functional test cases performed under peak load.
Basically, soak testing is running the same high load tests for extended periods to check if the system stays stable even in cases when peak load lasts for days or more.
Spike and stress testing
These tests typically focus on assessing how the system can handle large numbers of users. In order to do that, testers run a process that creates multiple virtual users, either in spikes followed by declines (spike testing) or by gradually increasing the numbers (stress testing).
Scalability testing focuses on measuring how well the system can scale by increasing the number of requests and monitoring performance in the process.
Runtime error detection
Runtime error detection focuses on testing the actual running of the API codebase in order to identify exceptions, resource leaks, and other types of runtime errors.
UI testing focuses on assessing the app’s user interface and how it is tied to APIs and other key parts of the application.
As we mentioned already, vulnerability detection is an important part of API testing. Security testing includes several practices, such as:
Testing focused on assessing the API layer to find threats and vulnerabilities that hackers can potentially exploit.
Fuzz testing sends a large amount of mostly random data into the system in order to detect if such an activity can be used to force a crash, overflow, or other kinds of system errors.
Validation and reliability testing
Finally, there are reliability and validation testing. This happens closer to the final stages of the development process. It verifies that all the main aspects of a product function reliably and according to the development goals.
Does the quality of APIs matter?
Since APIs are a way to ensure the highest quality and reliability of the end software product, it stands to reason that choosing a professional and solid API certainly matters. It should be a priority in the early stages of the development process.
Apilayer is a powerful suite of productivity-boosting web APIs & cloud-based microservice applications for developers and companies of any size. It includes many high-quality APIs that are easily integrable and highly reliable. As an example, ipstack is a scalable IP address geolocation and reverse IP lookup REST API. It provides you with access to IP intelligence data that can be utilized to take control of your web audience, enhance user experience and prevent fraud efficiently.
Benefits of API testing
To wrap up, here are some of the most crucial benefits of API testing and the reasons why it should be an integral part of your software development process.
Start testing early
You can plan and execute API tests in even the very early stages of the development processes soon after you design your application logic.
You can use any programming language for API testing. This is because APIs exchange data in testing scenarios in XML and JSON formats.
Because APIs don’t rely on UI, browsers, and other frequently changed tools and components used to access the data, it is much easier to maintain API tests.
And, of course, API tests allow developing teams to get results much faster by automating processes and creating complex scenarios that cover multiple functions of an application. This leads to faster releases in line with agile development methodologies.
Ready to start deploying powerful APIs in your projects?
Apilayer offers over 20 APIs that can increase your productivity. They are super to implement as well as to integrate into your testing pipeline.