Payment Gateway Testing: The Ultimate Guide With Use Cases

If you’ve done any online shopping lately, it’s safe to assume your transaction was completed through a payment system or a payment gateway. This type of application may seem small compared to major eCommerce stores or media platforms, but it is both absolutely indispensable and completely ubiquitous in today’s internet landscape, illustrated by their revenue that increases year after year.

However, behind every great payment solution, there is an incredible amount of work from development and testing teams. Testing payment systems is the only way to make sure they perform flawlessly, have an appealing UX, and can withstand the variety of security threats present today. In this guide, we will tell you why testing payment gateways is important, how it works, and what kind of challenges you can encounter along the way.

What Are Payment Systems and Payment Gateways?

Online payment systems and payment gateways are two terms that are often used interchangeably. But are they really the same thing? No, these are two different payment options, although they do have a lot in common. Let’s look at the definitions of both solutions and why they are different after all.

A payment gateway is a software solution that acts as the bridge between the customer, the merchant, and the bank, transferring the details of the transaction back and forth along the line. You can think of payment gateways as the virtual-only alternative to POS terminals used in stores and other establishments. It deals with the authorization and processing of online payments and mainly relies on the front-end part that users interact with directly.

A payment system or payment processor is an application that is responsible for the complete processing of online transactions. While payment gateways are more focused on the front-end part, payment processors do the heavy lifting of online payments. In addition to communicating the payment information between the customer, merchant, bank, and credit card association, payment systems also check funds availability, perform fraud detection, and handle chargebacks in case of disputes.

Payment gateways and payment systems do not operate in isolation and are, in most cases, interconnected. This is why most payment testing projects focus on both the payment gateway and the payment processor, although that depends on the solutions implemented in the product: sometimes, it’s enough to test just the payment gateway and the way it is connected to the payment processor, while testing of the processor itself is primarily done by the supplier.

Why Is It Important to Test the Payment Process?

Testing is an integral part of any software development process, and one cannot be imagined without the other. Testing ensures the spotless functionality, utmost stability, complete security, and engaging UX of a software product. However, there are product types where testing is even more indispensable, and payment systems definitely belong on that list. Here are just a few reasons why payment gateway testing is absolutely crucial for your project:

• Stability and scalability. One of the worst things that can potentially happen to a payment software product is being unprepared for a sudden spike in transactions or the user load increasing at a faster rate than expected. Timely testing ensures that the system can handle any workload without any performance gaps.
• Data integrity and security. Any guide to payment gateway testing will tell you that tight security is what users expect from a payment system in the first place. Testing and quality assurance helps keep security risks at bay, making sure the sensitive payment data stays intact.
• Regulatory compliance. Depending on where the product will be made available, you will need to ensure the system is compliant with all the relevant regulatory requirements — these may be specific to the financial domain, such as AML/CFT regulations in the United States, or applicable to all software released in a certain location, such as GDPR in Europe.
• Data-driven decisions. With payment systems, testing can provide a valuable opportunity to make important business decisions that are based on precise calculations, large volumes of data being processed, and accurate predictions being made by AI and ML-based tools.
• Proactive issue resolution. There are plenty of things that can go wrong with a payment gateway, but comprehensive testing allows the product team and the stakeholders to anticipate problems before they become a real threat to the app’s performance, security, or UX, getting rid of them exactly where they do the least amount of damage.
• Continuous improvement. For online businesses, it is crucial to constantly improve their services, keeping a valuable competitive advantage and avoiding the common business pitfalls that come with a stagnating product. A testing team that is involved in the project long-term will always find new ways to further improve the product.
• User satisfaction. With plenty of different payment methods available online, users are only going to stick around a payment system that delivers flawless performance and an equally flawless user experience. And that is only possible when payment testing services are an integral part of the product development process.

Common Types of Payment Gateway Testing

The exact set of testing types to be used on a payment system testing project depends on the specifics of the product, the goals of testing, and many other factors. Still, some types of testing are more relevant than others for payment solutions, and here are the ones that are most likely to be included in payment app testing services.

Functional Testing

Functional payment gateway testing verifies the correct functionality of the product — in other words, whether the website or application does everything it is expected to do according to the requirements. To efficiently test the functionality of the product, the team must have some insights into the payment process, although black box testing techniques also work well here.

Performance Testing

Performance testing involves verifying the way the application operates in different situations and under different conditions. Performance testing, along with its subtypes like load testing and stress testing, is indispensable for payment systems because it points towards the performance bottlenecks and potential operational gaps that would otherwise be discovered by users, which would inevitably damage the product’s reputation.

Usability Testing

Payment gateways are technically complex systems, but they are created for real human beings to use, and whether or not those human beings enjoy using the application will directly impact its future in the market. Usability testing exists to ensure a consistent payment experience that is equally accessible to all users regardless of their technical proficiency and does not create additional challenges for users completing transactions.

Security Testing

An impenetrable, fully secure payment system is nothing short of an industry standard. As users are getting more aware of the potential security risks and how elaborate online scams are getting, they will want to make sure the payment gateway is secure before they trust it to handle their sensitive financial information. For the payment card industry, data security is vital and can only be fully ensured through continuous testing.

Localization Testing

Oftentimes, a payment gateway processes transactions globally, not limited to any particular location. This means that the application should be available in every target language, and the translations should be as accurate as possible. On top of that, localization testing is also used to ensure that the payment solution uses correct currencies, time settings, and does not violate local laws. 

Compatibility Testing

With billions of smartphone users in the world, hundreds of available models, lots of operating system versions, and an endless number of their combinations, the variety of platforms is not something you can afford to ignore as someone who develops payment gateways. This is why it’s crucial for payment systems to be tested for device compatibility, and a little later in this article, we will discuss why it’s important to specifically test on real devices rather than emulators or device farms.

Accessibility Testing

Inclusivity is a growing concern in the world of financial software. Developers must make their products accessible to the widest category of users, including users with disabilities and physical limitations that prevent them from accessing the solution in the regular way. Software testers, in turn, need to check the accessibility with different groups of users and physical requirements in mind.

Integration Testing

One of the reasons why banking and financial software has been able to grow at such a rapid pace, both in terms of functionality and availability, is that financial applications are often developed with the help of individual products combined into one functional solution. Payment processors are also often used as part of a bigger product, which is why integration testing is required to check the way the final product operates. 

Regression Testing

This is one of the testing types you would find on any testing project, not just as part of payment software testing services. Regression testing purposes are plain enough: to check whether the software product was negatively affected by the recent changes to the code — particularly during bug fixes in the previous round of testing. Regression testing allows teams to release software with confidence and with a lower risk of new bugs appearing.

Compliance Testing

In different local and foreign markets, banking and financial products, including digital payment methods, need to comply with regulatory requirements. These requirements exist to ensure the integrity of the software, the responsible practices of processing and storing user data, the absence of security risks, and other essential parameters of reliable software users can trust. Only a team with relevant experience can plan and run the tests for compliance, as the world of regulatory compliance is enormous, and regulations change frequently.

Automated Testing of Payment Systems

Test automation is a perfect fit for payment solution testing. It helps get the most reliable results of testing and avoid many of the quality-related risks while saving time and resources compared to manual testing. But what should you automate in the first place for a payment testing project? Here are the testing activities that make particular sense to automate:

• Functional testing — checking the payment functionality, transactions, card statements, payment history, etc.
• Regression testing — making sure the recent changes to the code did not negatively affect the application as a whole.
• API testing — testing the APIs integrated into the end product, both on their own and as part of a larger system.
• Performance, load and stress testing — ensuring the payment application can withstand any number of users and transactions.
• Security testing — performing comprehensive checks to make sure the app is impenetrable for those who want to interfere with data.

The success of automation testing depends on several factors: the skills and experience of the team, the match between the project specifics and its goals, and the correctly selected stack of tools and frameworks. The choice of tools to use on the project is directly linked to the tech stack used to create the product. For example, when it comes to API testing, there are specific tools for each programming language used to create the API: there is REST Assured for Java, Requests module for Python, and so on. At the end of the day, the team uses a set of metrics to determine whether the setup is successful and whether the automation efforts pay off, or whether there are additional steps that need to be taken.

Preparing Test Cases for Payment System Testing: What Needs to Be Tested

The exact set of test cases for a payment gateway testing project will always depend on the project requirements, the specifics of the product, and the goals that need to be achieved. Still, having provided testing across dozens of payment systems and other related products, we have a firm grasp of what the team must test in a payment solution and what this segment of testing covers. Here are some of the most common sample payment gateway test cases to get you started:

• Credit card authorization. Here, the system must take certain parameters, such as credit card details, currency, user’s location, and others, to verify that the payment is authorized by the bank and allowed to proceed.
• Payment confirmation. Once the payment is processed, the testing team needs to ensure that it proceeds correctly and that the user receives a timely confirmation of the payment, while the bank or card issuing company also gets a payment confirmation on their end.
• Connection check. A stable, uninterrupted internet connection is integral for the correct operation of the payment solution. For this stage of testing, the team will simulate different conditions to see how they affect the connection, and how the interruptions in the connection, in turn, affect the payment process: for example, whether the user gets a corresponding error message and whether the process resumes after the connection is restored.
• Exchange rates. When the product is going to be available globally, one of the key tasks for the testing team is to ensure that the payment gateway uses correct exchange rates for all currency pairs. The exchange rates also need to be updated swiftly when they change, which is why the testing procedure should also include verifying how quickly it happens.
• Negative scenarios. A significant portion of payment gateway testing ensures that the payment is completed successfully. However, that is not always the case, and an online payment can fail for a myriad of reasons. The team’s job is to account for both common and unlikely scenarios, overseeing the way the system reacts to payment failures and what options the user has for aborting or resuming the transaction.
• Security checks. One of the most important things to check while testing a payment solution is the security of the application. Some security tests, like penetration testing and security scanning, need to be automated to cover as many scenarios as possible, but it is also possible to do manual security checks. For example, the team may test password rules, password and username strength, fail-open authorization, input validation, trust relationships, and more. Many teams use enterprise password managers to securely handle credentials, minimizing access risks during testing.
• Refund processing. Refunds are a common byproduct of online transactions, and depending on the merchant’s policy, the refund can be requested and issued months after the purchase. This means the team has to make sure that all relevant data is stored securely for an extended period of time to make the refund possible, and that the refund itself works smoothly for all parties, including the customer, the seller, and the bank.

The Specifics of Testing in the Payment Domain

Many of the techniques and approaches in testing payment systems are widely used in testing other types of applications. However, payment testing also has a few techniques and trends of its own, and here are some of the key specifics of testing payment applications.

• API testing. Most payment systems are comprised of several smaller solutions, typically carried out through the API technology. This is why, when it comes to testing payment methods, API testing is an integral part of the process: each API has to be tested both individually and as part of a larger application. While it is possible to perform API testing manually, sooner or later, it has to be automated. Since APIs don’t have a user interface, testing these products works better when the team has access to the code. Automated testing of APIs takes time for writing the tests initially, but it saves resources in the long run and increases the accuracy of the results.

• Testing in real-life conditions. When it comes to testing payment gateways, sandbox testing and virtual card simulations are widely used throughout the project. However, the closer the product is to the release, the more important it becomes to also test it using real-life conditions and real credit cards with real money on them. This gives the team and the stakeholders a comprehensive idea of how the app behaves in real life and helps mitigate the risks of releasing an undertested product.

• Beta testing. A common technique for testing payment solutions is to release them to a small group of users, have them fully interact with the product as they would with a regular payment system, and collect the bugs they discovered. However, as effective as this technique is for gauging the real-life experience of using the product, it cannot be viewed as a substitute for professional testing, as it takes an in-depth knowledge of software QA to do the most thorough job.
• Stress testing. We’ve already touched on the importance of performance testing and load testing for apps that deal with payments and transactions. In addition to that, we would like to point out the importance of stress testing, which is used to see how the app behaves in situations that venture from its normal operations. From Christmas shopping to the start of ticket sales for Taylor Swift’s next tour, using stress testing to prepare even for the most grueling scenarios can save the stakeholders from a lot of trouble.
• Data testing. Data testing is a relatively new trend in software testing and, as the name gives away, it deals with data — specifically, the data produced by, stored, and exchanged through the payment system. Data should be checked for consistency, integrity, relevance, absence of duplicates, and so on. This type of testing is also closely connected to compliance testing — in particular, compliance with regulatory requirements concerning the handling of user data.
• Shift-left testing. This trend is something we are witnessing more and more all across the software testing field, but it is also dominating the payment gateway testing segment. The shift-left approach to testing moves the quality assurance activities to the beginning of the development lifecycle, allowing the testing team to get involved from the start and begin performing quality assurance despite the fact that there is barely any code written. This results in cleaner, durable code that creates high-quality and scalable products.

How to Test Payment Systems and Payment Gateways

Having delivered payment gateway testing services for over 15 years and for dozens of clients, we have time and time again come to realize that precise planning is just as important for the success of the project as making immediate decisions based on the project specifics. This is why, while we always leave room for adjustments, our procedure for testing includes certain steps and activities we cannot do without. Here is how we approach testing payment applications.

1. Determine the Scope

Together with the project stakeholders and developers, the testing team will determine the scope of testing, e.g. what needs to be tested and on what scale. Taking the time to complete this step will save the team from wasting valuable resources and will help keep the testing process streamlined.

2. Create Use Cases

This is the stage where the testing team, along with business analysts and other specialists, work to create user personas and use cases for the application. For this stage to work properly, it is integral for the team to account for the whole variety of users and their needs, creating a diverse range of user personas, who, in turn, will influence the number and variability of use cases: the more potential scenarios are covered during testing, the more successful the release is going to be.

3. Prepare Test Cases

Using the information obtained at the two previous stages, this is where the testing team will create detailed test cases to be executed later. Depending on the specifics of the product, the test cases will be focused on functionality, security, compatibility, performance, accessibility, and other parameters of a well-tested payment gateway. The in-depth description of the steps and conditions contained in test cases for payment gateway testing is crucial for continuity in case another testing team has to take over or the developers need to replicate the event.

4. Get the Infrastructure Ready

Testing payment systems requires the use of specific infrastructure, which may include various hardware and software, as well as testing environments. For payment gateways, it is essential to test the application on different mobile and desktop devices, as well as on different operating systems and in different browsers. And while there is an option of using device emulators and farms, at the end of the day, nothing beats the efficiency and reliability of testing on real devices — the way we do it at TestFort.

5. Run the Tests

This is an integral part of the testing process where the team goes over the test cases one by one, executing the tests and noting whether they passed or failed. This process should run according to the predefined plan, and the team should watch out for any test runs that produce unexpected results. In most cases, this stage will include initiating a transaction based on a specific set of conditions, entering payment details, and completing the payment, or using different techniques to prevent it from being completed.

6. Observe the Outcomes

A vital part of testing a payment gateway is evaluating the outcome of the test run. Was the test successful? Did it happen the way it was described in the test case? What did the process feel like to an average user? Were the transaction stages and the accompanying system messages easy to understand and informative? Examining the payment process from the standpoint of a user is a highly useful activity that adds value to the testing process.

7. Document the Results

Documentation is a sometimes overlooked aspect of testing, but we cannot stress the importance of documentation enough. Documenting the process and especially the results makes them more tangible and easily accessible for the team, both the people currently involved in the project and the people who will be involved in it at later stages. Documentation can also be used by developers and project stakeholders, so this is not a step that can be omitted or taken lightly.

8. Create Reports and Analytics

Once the testing team has enough data, they should turn it into reports and use various tools, including AI-based ones, to describe the state of the application, its functionality, stability, performance, usability, and other essential parameters. Detailed reports and robust analytics will give the developers and other stakeholders a complete picture of where the product’s quality stands at the moment and what can be done to improve it.

The Importance of Testing on Real Devices

Here at TestFort, we pride ourselves on testing software on physical devices, and that includes payment solution testing. Our procedure for payment system testing involves checking the product on 250+ real devices ranging from entry-level smartphones and tablets to flagship devices, and that helps us ensure a few vital outcomes:

• Testing the solution on different combinations of devices, versions of operating systems, and settings allows us to cover hundreds of target device setups, making the system’s behavior more predictable regardless of the platform or the user’s preferences in setting up their devices.
• Using physical devices for testing a payment processing system and other types of payment solutions allows us to utilize all the software and hardware infrastructure available on the device, including various sensors, biometric authentication solutions, and built-in payment systems like Google Pay and Apple Pay.
• Employing a fleet of real devices is the only real way to check the way the application being tested is impacted by the variety of events that take place on a mobile device, such as notifications, calls, system alerts, error messages, network and internet connection issues, and applications running in the background.

Challenges of Testing Payment Gateways

Payment gateway testing helps businesses make sure their software is release-ready and able to compete with the market leaders. And the payment system QA field has come a long way since its inception, introducing different types of testing, techniques, tools, and best practices to make the process more effective. Still, like any QA activity, testing payment systems has its challenges, and here are the most common ones.

Increasing Complexity of Systems

Online payment systems are getting more and more elaborate and include more and more cutting-edge functionality. In addition to testing credit and debit card payments, testing teams now also have to focus on cryptocurrency and other advanced technologies as well. Plus, as scammers are getting more creative with their attempts to steal sensitive information, testers should also get more creative with their testing approaches.

Variety of Integrations

In the online payment landscape these days, there is no shortage of range. There are dozens of diverse payment methods available, and those are integrated with an even bigger variety of banking, financial, and eCommerce solutions. As a result, testers often have to deal not just with the payment gateway itself, but also with the way it operates with other systems, and the sheer number of possible combinations can be overwhelming for a team with limited resources.

Intricate Regulatory Requirements

As eCommerce and online payments are becoming more of a mainstay in our lives, governments around the world are making an effort to control the industry and prevent fraud and user data getting mishandled. There are numerous regulations specific to the financial domain in most foreign markets, which means the more locations you want to release your product in, the more regulatory requirements it will need to comply with, and the complexity of the regulations is a challenge on its own.

Outdated Testing Infrastructure

Testing advanced software solutions requires the use of equally advanced testing infrastructure. Unfortunately, that is not always the case, particularly when the company is trying to keep the testing operations in-house. In that case, the testing process may not end up meeting all the project goals. Plus, the cost of testing may increase because the outdated infrastructure requires more time and effort to complete a simple task. Entrusting testing to a trusted provider with all the necessary infrastructure is a great way to alleviate those risks.

Final Thoughts

Payment systems and payment gateways are one of those software types that are everywhere around us, even if we don’t always notice them. And even though there are a few great payment solutions in the market already, with the growing number of online transactions, there will always be room for more. At the same time, it’s important to remember that users are not going to have much patience for an application that is riddled with usability bugs or much trust for a product that has been involved in security-related controversies. Timely and all-encompassing software testing helps nip those risks in the bud, and we hope that our guide has made things clearer for you in this regard.