Learn These Key Functional Testing Types and Programs

The functional testing types below, therefore, are neither sequential nor required for every application. Consider the advantages and disadvantages of each type of functional test, as well as the time and resources available to commit to QA.

Functional testing types

Let’s explore these types of testing with examples:

• Unit testing
• Component testing
• Smoke testing
• Sanity testing
• Regression testing
• Integration testing
• API testing
• UI testing
• System testing
• White-box testing
• Black-box testing
• Exploratory testing
• Acceptance testing
• Alpha testing
• Beta testing
• Production testing

Unit testing. Before you can test an entire software program, make sure the individual parts work properly on their own. Unit testing validates the function of a unit, ensuring that the inputs (one to a few) result in the lone desired output. This testing type provides the foundation for more complex integrated software. When done right, unit testing drives higher quality application code and speeds up the development process. Developers often execute unit tests through test automation.

Unit testing example: A developer builds a calculator app. A unit test would check whether the user can input two numbers and receive an accurate sum. Separate unit tests would validate other calculator functionality, such as subtraction, multiplication and division.

Component testing. Also called module testing, component testing checks individual parts of an application. Similar to unit testing, component testing assesses a part of the software in isolation from the broader system. The difference between unit testing and component testing is that the former is done by developers in a white-box format to verify that program modules execute, while the latter is done by testers in a black-box format to validate individual objects or parts of the software. If other software components rely on the component under test, the QA professional might use a stub and driver to simulate interactions between those dependent components.

Component testing example: A banking mobile app includes an option to schedule an appointment with a banking professional. The stub provides a simulated user profile, and the driver provides a simulated schedule of available appointment times. In this functional testing example, the middle component — the one under test — finds the user’s location via GPS and displays local banking centers from which they can choose. By testing this component in isolation, the tester can ensure that the geolocation service works correctly and displays an accurate list of nearby locations.

Smoke testing. A type of acceptance testing, smoke testing provides an initial check that a new software build and its critical functionality are stable. If the smoke tests pass, the build can undergo further testing. Smoke testing, also called build verification testing, checks whether new or critical functionality meets its objective. If the tests don’t pass, as the saying goes, “where there’s smoke, there’s fire,” and additional dev work is required.

Smoke testing example: A web app for an insurance company adds a claims status page. Testers would apply smoke tests to verify that the existing build works on a fundamental level. In this functional testing example, they would validate whether a user can successfully log in, navigate to the claims status page and retrieve the status of a specific claim.

Ebook

Ebook

White-box testing. When the software’s internal infrastructure, code and design are visible to the developer or tester, that refers to white-box testing. This approach incorporates various functional testing types, including unit, integration and system testing. In a white-box testing approach, the organization tests several aspects of the software, such as predefined inputs and expected outputs, as well as decision branches, loops and statements in the code.

White box testing example: In this functional testing example, consider an end-to-end test for a customer who adds payment information to a retailer’s app. Developers and testers would conduct tests in a white-box format to ensure that sensitive data, such as a credit card number, is stored in a PCI-compliant manner. White-box tests might also ensure that purchase information flows to a machine learning algorithm to generate predictions, the purchase correctly generates rewards points, and the inventory system deducts the items from the stock count.

Black-box testing. Contrary to white-box testing, black-box testing involves testing against a system where the internal code, paths and infrastructure are not visible. Thus, testers use this method to validate expected outputs against specific inputs. Any time where a QA professional doesn’t look into the code before testing can be considered black box. With black-box testing, the organization can test the software in the same way a customer would experience it. Black-box testing encompasses a variety of non-functional and functional testing types, depending on the objective of the test. 

Black box testing example: On a streaming television platform, the tester toggles the search functionality and executes a search for a specific actor. The tester then verifies that the search feature returns logical (expected) outputs, including television shows that the actor appeared in, or suggested titles similar to that actor’s well-known works.

Exploratory testing. Exploratory testing involves testers exploring the application to discover potential issues. Unlike other types of functional testing, exploratory testing does not rely on predefined scripts. This technique allows testers to use their intuition, creativity and experience to find unexpected problems that structured tests miss.

Exploratory testing example: A tester uses a new e-commerce website and experiments with adding products to the cart, removing items, applying discount codes, putting nonsensical items in entry fields and navigating across different pages in a random manner. Through this exploration, they discover that applying a discount code after removing items causes an unexpected error.

Acceptance testing. The purpose of acceptance testing is purely to ensure that the end user can achieve the goals set in the business requirements. Rather than focus on functionality of specific features, acceptance testing involves reviewing the feature-complete application flow and end-to-end experience. User acceptance testing (UAT) and beta testing, subsets of acceptance testing, involve end users to conduct their analysis of the finished product. From there, the organization can evaluate that feedback and make changes.

Acceptance testing example: A software company releases a product that enables its users to manage big data. Upon release of a new version of the software, a group of that company’s most significant users conducts user acceptance testing to determine whether the new version meets their primary needs and how the product can be improved.

AI testing. A lot of work — and data — goes into testing and training AI-based algorithms. But it doesn’t stop there. AI testing against a variety of criteria ensures that AI and ML systems function as expected. It’s just as important to validate generative AI systems to root out bias and inaccuracies.

Applause provides AI training and testing, including for specific quality attributes like model bias, accuracy and data quality. Applause community experts provide real user perspectives, testing for devices where the system will run and check against AI bias. Without proper training and testing, it’s hard to realize the value of AI and ML — take the time to do it right.

Customer journey testing. Nearly every company connects with consumers across multiple channels (e.g. mobile, web, social, in-store). Thus, customer journey testing, or omnichannel testing, is essential to the end-to-end experience. Customer journey testing uses real people to test an experience from one channel to another to ensure consistent digital quality and continuity of experience.

The Applause community of experts helps brands achieve alignment and smooth customer experiences. Take advantage of testers in the markets and demographics you need. Receive actionable feedback to reduce customer friction.

Payment testing. For any transactional system, payment testing is critical to success. With payment testing, users validate select payment methods, such as credit cards, debit cards, mobile wallets and P2P platforms. Payment testing ensures that currency can seamlessly change hands from the consumer to the business and a transaction can be processed.

Applause conducts payment testing with real users around the world, in different currencies for both digital and physical transactions. When it comes to financial transactions, it’s not good enough to simply hope the payment processes. Ensure your revenue stream works as it should with payment testing.

Security testing. All apps and websites require robust security to maintain consumer trust and protect both data and intellectual property. Automated scans and assessments are a common part of security testing. Active testing elements should bring the human side into testing as well.

Applause provides a global team of white-hat hackers to penetration test your digital products. These penetration tests may include techniques such as SQL injection, cross-site scripting (XSS) and other common attack vectors to identify vulnerabilities. These penetration testers attempt to break into your protected system to identify vulnerabilities. Applause provides these insights within our platform. And our experts offer a breadth of knowledge and experience to give peace of mind that a release meets high security standards.

User experience testing. Contrary to user acceptance testing, user experience testing considers user opinions. It’s important to have functional digital products, but it’s also crucial to have products that customers can easily use — and, ideally, like to use.

Applause conducts user experience testing led by a qualified UX researcher. We run through our global community of experts based on your customer profiles. You can run various types of studies to collect detailed user feedback that helps identify areas or features to improve the user experience.