Best practices for API Testing: the top 5 lessons learned by Solvd’s testers

api testing best practices
By Katrine Spirina, Content Manager

An application consists of several layers, while a service layer (API) contains the business logic. It’s the core of application software development that connects multiple apps and enables data transfer. 

Software developers spend 29.5% of their time on creating an application programming interface (API), according to Statista. Almost the same amount of time, 27.8%, is required for manual and automated tests. But business owners may sometimes wrongly prioritize development efforts over QA work, which jeopardizes the quality of their software solutions.

By allocating enough time and resources for testing API endpoints, you can drastically improve the quality of your solutions and deliver the product faster.

That seems intuitive enough, but let’s take a closer look. Read on for five lessons our QA and test automation specialists wish to share about API testing pitfalls and their best possible solutions.

What is API Testing in QA?

All test activities generally fall into mobile, web and API testing. The first two aspects relate to functional tests that verify the proper functioning of UI elements, including buttons, pages and images. API verification means dealing with just the code.

Using API test automation best practices or by performing tests manually, QA engineers work directly with code and have little to no visualized entities that usually facilitate running tests. They send lots of API requests and check to see if it responds with the correct status and data.

Testing requests are swift, but the API responses received contain tons of information, which is not just the only challenge with API testing. If you think testing code strings is simple, think twice and follow this article.

API testing in QA

If you think that Testing API is a piece of cake, you’re wrong

Simply put, it requires straightforward testing. If you’re lucky enough, you’ll have comprehensive documentation and a well-defined interface. So, your tasks will boil down to sending API calls, verifying API responses and reacting to error messages.

If you have an API suite that involves thousands of tests, it would probably take you several minutes at most to run all those types of tests. Meanwhile, you may spend hours testing the UI of mobile applications because of the wide variety of devices and platforms.

Unlike UI verification, running tests for APIs is easier and faster. You don't even need drivers to connect with other devices; debugging processes are a lot easier than on web or mobile testing projects, and infrastructure issues are unlikely.

But don’t let the seeming simplicity of this type of tests fool you. APIs have an extremely complex infrastructure, including a massive number of testing entities that contain hundreds of fields with very little visualized information.

For example, when QAs test scenarios for the UI of an e-commerce website, all of the information they need usually comes explicitly. If they lack some explanation of what’s going on in the tests, they may browse a webpage or item description and verify the logic of the intuitive attributes like price, size, color and others.

Now, let’s say they need to test fintech APIs. It may be extremely hard and puzzling, given the non-transparent nature of financial solutions, security requirements and the strict regulations specific to the banking and finance industry. QA engineers may have to deal with a wall of text describing specific financial terms, features and working principles that they need to clarify for themselves before they run the tests. Manual and automated API tests for fintech can become a nightmare – even for a highly qualified team.

Best practices for API Testing: these 5 tips can save the day

If you’re outsourcing API and web services testing, remember that you can help make a big contribution when supporting a QA team.

When you need to ensure adequate team management, use API testing best practices and the most advanced tools and infrastructure, use realistic data, focus equally on mundane tasks and high-flying issues, and use service virtualization.

For some projects, error messages on those aspects won't be critical. But when it comes to testing fintech or other data-rich and sophisticated applications, the cost of a mistake might be high.

1. Don’t tolerate poor management

When you need fintech API testing, prepare to respond to multiple queries from the team about the working principles of your solution. A fintech application, by nature, isn't intuitive. It isn’t something QA and test automation engineers on typically deal with on a daily basis, unlike e-stores or service websites.

Team managers should be in touch whenever team members need them to explain specific entities, fields or features. It can be challenging if your QA team is scattered across different time zones. Check our tips on managing remote teams or simply check to see if we work in your time zone – there’s a very high probability that we do. At Solvd, we have the capacity to offer you QA specialists as per your location, and we consult with you about establishing and maintaining communication with the team.

2. Stop using legacy infrastructure and outdated tech stack

You need to work with up-to-date and customizable platforms that allow more flexibility and let you use the latest technology features. However, it’s all right if some projects require support for legacy solutions and approaches. In some cases, migrating fintech solutions in the short run might be insecure, and the process has to comply with strict industry regulations and high security standards.

If your team has to use legacy tools and architecture, be ready because the testing processes may take much more time than you might expect. QA specialists might have to compromise on quality. They should test critical aspects first to make sure the basic functionality is in working order, and only then could they make some improvements, deadlines permitting.

You may facilitate working with legacy technology and tools by providing your QA team with up-to-date and detailed fintech API testing documentation. Guides, manuals and requirements for tests should be as clear and as comprehensive as possible. That allows QA engineers to get down to their core tasks while skipping redundant explanations.

3. Always test non-obvious data relations and use realistic testing data

The closer the test data resembles the conditions of how real-user API requests will interact with API, the more reliable these types of tests will be. It's vital to bridge the gap between business users and API testers. To that end, your QA team should start at the source and always keep in mind the business procedures that the API was created to serve. The API's purpose and the data it will receive during design and implementation should remain the priority throughout all the tests. 

In addition, professional QA testers should consider the potential of various non-obvious relations between data. Some specific input values might be based on other information transmitted to the API, and specific conditions might be applied when an API receives return data. Having the right tech stack and employing API testing best practices, test engineers can accurately reflect these relations in test data.

API testing tips

4. Use service virtualization for API Security Tests and more

QA teams shouldn't imitate themselves over and over in the number and variety of cases and scenarios they can use to test the work of all services and endpoints. To do this, they can take advantage of service virtualization - an invaluable tool for testing APIs that lets developers and testers simulate complicated, connected systems that could be hard to get to or reproduce without it. It also makes it possible to test APIs in different environments and configurations without having to deploy a new version of the application or build a new environment for each and every change.

Most significantly, the service virtualization tool can help do security tests of different settings and make sure your app is well-protected. With the huge number and complexity of attacks against APIs, it’s important to implement a comprehensive security testing strategy and adequately prepare the API to resist attacks.

5. Don’t focus just on high-flying issues while neglecting simpler tasks

Believe it or not, cornerstone issues like incomplete documentation, poor communication or the wrong choice of methodology and API testing tools online affect your project more than using a less popular API testing strategy.

Focus on where you are in your testing journey at this moment. Perhaps your acute goal is to update tools and API testing scenarios or streamline your QA management activities. If you have already passed the early stages, think about ways to increase your team's efficiency and make the best use of your customer feedback.

Wherever you are in the process, focus first on the routine issues that slow down the whole process before the QA processes can get shattered. Move step by step, resolve current concerns and set up robust cooperation within a team that complies with API testing best practices.

Frequently Asked Questions

The key hurdles you might face are:

  • API testing requires automation, as it's a complicated process that needs speeding up. That requires skilled testers to use API test automation best practices and tools effectively.
  • Security threats to APIs are incredibly high, so QA and automation testers should check the API’s security features, such as authentication and authorization, to ensure that it’s completely secure against any and all potential threats.
  • Performance issues can arise from API integration, latency in response time or slow execution, and professional testers should verify that API performance meets the desired standards.
  • Poor or inadequate documentation can make it difficult for testers to understand the API’s functionality and how to use it effectively. Make sure you provide your team with accurate and understandable information.

Manual and automated API tests shouldn't be used to test user-facing functionality, such as the look and feel of your website or the usability of your application. Also, QA testers and software developers shouldn't employ this type of tests as a substitute for unit, integration and performance testing.

In Conclusion

API testing can be done by different software development and QA vendors while using various automation tools and manual testing approaches. At first glance, it may seem like a piece of cake, but it requires a complex approach, with the knowledge of API testing best practices, the potential blatant mistakes and the non-intuitive issues to avoid. 

Be very careful with the input you provide about your business niche and project scope. Also, invest the time and resources needed in scaling up a QA team, maintaining project documentation, and keeping the tech stack you use up-to-date. The overall efficiency of the work our QA engineers can do for you depends on you, so make your processes and business goals as transparent as possible for a QA team, and you’ll help attain the best possible results.

Katrine Spirina
Katrine Spirina
Content Manager
Katrine Spirina graduated from MSLU with a Bachelor's degree in Linguistics and Education. She enjoys keeping up on the latest advances in AI, VR, robotic automation and smart home gadgets. Her articles have been published on Computer Weekly, Clutch, ITProPortal, HackerNoon and Towards Data Science.

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