12 Types of Functional Testing in Software Testing

Functional testing checks if the software does what the user expects it to do. Here you will get to know about different types of functional analysis which is used during software testing. Each of the types above can be based on features, user actions or system behaviours. These tests help the team to discover problems early on, so they can improve the quality and the user-friendliness of the software. When developers and testers have knowledge of all the functional testing types, they can develop and test products that run well, meet user expectations, and are enjoyable to use. This whitepaper provides a high-level introduction to the interplay between the two types of testing and the benefits to software quality.

What is Functional Testing?

Functional testing is a testing process that ensures that the software behaves as expected. It is concerned with the results of processing rather than with the processing itself. In layman's term, all buttons, forms, links and features are tested under functional testing to know the output is as expected or not. Functional testing is web site testing to determine what happens when users click on links and buttons.

Many types of functional testing are commonly used in software testing. There is a different software testing for every stage and for each component. Some are aimed at testing individual components, others at testing complete systems. These types of testing enable you to catch issues early on, before your users do. Software functional testing is a way to help software be safe, smooth, and user friendly.

With various types of functional testing, the team can verify that all the parts of the application work together as expected. This way of testing is quite significant in software development as it enhances software quality and user confidence. When functional testing works well, users receive software that behaves as it should and does so consistently – every time.

Different Types of Functional Testing

Various forms of functional testing play a vital role in ensuring proper functioning for each and every feature of the software. Each one validates the software from a user’s point of view and focuses on the results that are expected. Both these testing types contribute to improvement in software quality, effective reduction of defects, and better user experience.

List of all types of functional testing:

• Unit Testing
• Integration Testing
• System Testing
• Smoke Testing
• Sanity Testing
• Regression Testing
• User Acceptance Testing (UAT)
• End-to-End Testing
• Interface Testing
• Alpha Testing
• Beta Testing
• Compatibility Testing

1. Unit Testing

Unit testing is the first and smallest phase of software testing. So it basically tests small unit of software one by one. This tiny section is known as a unit. A unit may be as small as a button, a function, or an entire feature. Unit testing ensures that each component is working correctly before it is integrated with other components.

This testing is generally performed at the early stage when the software is being developed. Early detection of problems saves time and strengthens the software. Unit tests give developers confidence in their own work. If all units do well, the entire software will behave better and break less.

The Significance of Unit Testing

• It tests small portions of the software individually, isolating defects is easy.
• It prevents large-scale errors by correcting small errors in the early stage of development.
• That makes the software more stable, secure, and dependable for the users.
• So, it saves time and effort as problems are resolved before testing in full.

Example Unit Testing:

Think of a page in an app to log in. A unit verifies the validity of the password. Another one verifies if the username is filled in. Unit testing evaluates each of these component prototypes on its own. If password checking works and username checking works and if all of this is combined together login works perfectly, so our login feature also works when we tie everything together.

2. Integration Testing

Integration testing involves the combination of modules tested as a group. Software is just a game with many little interacting parts. Each individual part may be fine, but when you put them together, they have to work together. Integration testing is to check whether these components can communicate with each other successfully or not.

As software gets larger, features rely on each other. If any component transmits invalid data, the dependent component may also break. Integration testing also helps locate these errors at an early stage. Before any real user starts interacting with it, it makes the software smooth, safe, and easy to use for them, making it fun and painless for the prospective users.

Why Integration Testing Is Important

• It tests the interaction between modules, not modules in isolation, so it is easier to identify interfacing bugs invariably before they cause other problems.
• Data flow anomalies, such as incorrect data transferred from one module of software to another that can mess up with whole system, can be tracked.
• It also saves developers and testers time and energy by allowing them to focus on work that they know won't be invalidated.
• And it ensures the quality of your software by verifying that all the integrated components you rely on are doing what you expect, in the real world. 

Types of Integration Testing

1. Big Bang Integration Testing: In the big-bang integration testing approach, all or most of the modules of the software are combined together to form a complete system and then tested in one go.
2. Incremental Integration Testing: Integration between modules takes place incrementally, one module at a time, allowing for earlier detection and correction of errors.

Example of Integration Testing

Take an e-commerce app for instance. One might be for products, another for payments, and a third for order messages. Integration test so that you know that purchasing a product, paying for it, and receiving an order message hook up properly. Payment is made but order message may not appear, and integration testing can be used to identify such a problem and fix it at an early stage.

3. System Testing

System Testing is performed after the completion of Integration testing and when the entire software is compiled. The entire system is tested as a whole during this testing. The aim is to verify the software functioning is correct and complies with all the requirements that have been planned. It tests the system as it’s actually used, where the user will use it.

System testing follows integration testing in the Software Testing Life Cycle (STLC). This testing is usually done by the testers themselves who didn’t develop the software. They run tests in an environment that simulates the real system that customers use, as closely as possible. System testing is crucial as it ensures that the software satisfies the technical, functional, and business requirements that the user and stakeholders expect it to meet.

Example:

System testing is executed when all modules are fully developed and integrated. For instance, in an Employee management system, testers verify all modules as a whole as employee records, leave applications, reports and performance tracking. They ensure that each component performs well within the system as a whole and produces the expected outcomes to the end users.

4. Smoke Testing

Smoke testing is done on a new build shared by developers to check whether the basic and most important features are working. It is one of the key types of functional testing and is always the first test performed on a fresh build. The main goal of smoke testing is not deep testing, but to quickly confirm that the software is stable enough for further testing.

In smoke testing, a subset of test cases of each testing type is executed to test the application whether it is working fine or not. These are the features without which no other testing makes sense. This is a convenience that can save resources from developers and testers alike.

A build that successfully passes smoke testing is considered stable. The QA team then conducts new function testing for new features and regress testing as needed. If the build does not pass the smoke test, it is discarded and sent back to the developers to resolve the problems and issue another build.

Example

Suppose a company builds an employee portal for daily office tasks. Features like login for employees, leave request, leave balance, employee details, notifications etc. Once the developers have finished a new build, it is delivered to the QA team to perform smoke testing.

Testing all the features of the system will be the responsibility of many test cases, but smoke testing select only the absolutely critical ones.

These smoke test checks include:

• User can log in successfully
• User can select leave dates
• User can enter leave details
• Leave request is sent to the manager

If these basic actions work, the build is accepted for further testing. But if even one critical step fails, the build is returned to developers. This early check helps prevent wasting time on unstable software and keeps the testing process smooth.

5. Sanity Testing

Sanity testing is done when a new build has small changes and bug fixes. So testers just run a quick check rather than executing full test cases to make sure that the recent changes are working fine and that nothing else is broken. It is considered to be one of the important types of functional testing and is generally regarded as a narrow regression test. Among software testing types, sanity testing contributes to time-saving, because it refers only to the testing of the specific areas touched by a particular fix when fixing an application.

Example

Consider an employee leave management system. A new build is released with a fix for a date selection issue. First, smoke testing confirms the build is stable. Then sanity testing checks only the date selection feature and ensures it works correctly without affecting leave submission or approval.

6. Regression Testing

Whenever developers make changes, add new capabilities, or fix bugs in software, they are performing Regression Testing. These modifications can lead to the malfunction of previous features, sometimes. Regression testing ensures that the existing functionality is still working as expected in the new upgraded version. Its purpose is to make sure that the modifications have not introduced new problems and that the old problems have indeed been fixed. A lot of testing tools facilitate regression testing, allowing testers to execute automated checks in a fast and accurate way.

Example

In leave management system, a new feature is added by the developers which displays the employee leave history reports. Testers confirm the new feature works, then do regression testing to make sure the old features like leave application, approvals, notifications are still working properly. Test scenarios from the previous build are reused to ensure nothing is broken.

Problems in Regression Testing

• The number of regression test cases increases for every new feature, which requires more effort to test in time.
• Due to time and budget constraints, it is not always possible to perform the full regression testing.
• Getting the right test cases for maximum coverage using minimum effort is not an easy task.
• Instructions on how often to do regression testing after changes or fixes can get mixed up.

7. User Acceptance Testing (UAT)

User Acceptance Testing (UAT) is the end of the road in the software testing lifecycle. At this stage, actual users use the application to check if it meets their requirements and works in real life. Typically, UAT takes place just before a product is handed over to period and it is generally considered one of the key phases in any type of functional testing. It is used to perform the final go check to determine whether to release the software.

During development, the application is tested countless times by the developers and QA before being tested with different methodologies. But those teams are so close to the system, they sometimes don’t realize this is not really how people use it. This is where UAT is useful. End users evaluate the software when they don’t have a clue of the internal logic in the software and are only interested in how the software acts and feels when they are using it.

They perform real workflows based on their needs and expectations that are similar to their daily duties. They do the above test and also sit down to find out if the app is easy to understand, easy to use, and whether it fulfills the business needs. Instead of attempting to destroy the system, users confirm that it naturally and smoothly works. UAT ensures software meets user expectations and adds real value before being deployed.

8. End-to-End Testing

End-to-End Testing authenticates the flow of an application for the user, and user interface is snapped up for testing at that level. This testing is performed to check whether the flow of an application is working fine or not. End-to-end testing is considered as one of the important types of functional testing and it ensures that the entire application flow is working as expected in the production environment.

In software development, various modules of an application like login, data entry, processing, alerting etc are developed individually. End-to-End Testing takes all those isolated components and smashes them together in an orbital flurry of unadulterated joy, all in one cohesive user experience! The purpose is to check whether software runs from the first to last statement without crashing or error.

Testers emulate the actions that typical real users perform on the website for example, logging in, completing a form, saving data, getting results. They check whether data is correctly flowing through the system, and the modules. End-to-end Testing is done with Users normal expectations of usage, and the system not to be hacked into the System. This type of testing can also be used to validate that the software is friendly enough, robust and can be delivered to the end users successfully.

9. Interface Testing

UI Testing is Testing the User Interface of an application. It is concerned with the screens, the buttons, the text fields, the colors, the icons, and the menus that we have to interact with daily. The purpose of UI testing is to validate if the application is visually appealing and functionally working fine while users are using it. UI testing can be performed manually or using automated tools, however currently many teams choose automation as it saves time and increases the accuracy.

In Interface testing Two aspects are tested: The behavior of the application in response to user input performs a sequence of input events (clicks, key presses and mouse moves) on the component. It validates that the software is what users want and that it’s a joy to use.

Typical Items to Look for in the UI Testing

• Menus, buttons, text boxes, check boxes and icons perform well and they are properly aligned.
• The colors, fonts and lays are bright and consistent within all pages.
• The Navigation Buttons are used to Navigate from one screen to another screen so level of confusion is least in that navigation.
• Whenever the user types in an invalid or incomplete input, error messages are displayed properly.

Example

A simple example for UI testing is a sign up form. Testers verify whether the labels are understandable, text boxes get valid inputs, buttons perform functions, error messages appear in right moment, and form can be submitted without any problem.

10. Alpha Testing

Alpha Testing is a testing method used to find and fix issues before software is released to real users. It is one of the important functional testing types and is done to improve software quality at an early stage. This testing catches even tiny issues so the product glides when it reaches its users. Alpha testing is conducted within the organization by the developers or the testing team.

Alpha testing is conducted after completion of unit testing and integration testing. It can be performed by using black and white-box testing techniques depending on the project requirements. This testing helps verify that features are working correctly, performance remains stable, and the software is ready for the next testing phase. Functional testing examples range (but are not limited) to alpha testing as a step before beta testing.

Alpha Testing Process:

1. Requirement Review: The tester analyze the software in terms of the requirements and the design to determine how the product is expected to behave.
2. Test Planning: A brief test plan is prepared for the purpose of specifying what needs to be tested and how the coverage can be obtained.
3. Test Case Creation and Execution: Creating and executing test cases to validate different inputs, working of applications, and output.
4. Bug Reporting: Any bugs, crashes, or holes in functionality encountered during testing are documented.
5. Bug Fixing: Those reported issues are handed over to the developer to fix them as the priority.
6. Re-testing after fixes or updates: After the fixes or updates, the testers recheck the software to confirm if the issues are resolved and to check if there are any new issues.

Example

A company creates a booking website that should allow for thousands of users to be online at the same time. During alpha testing, the in-house team logs on as numerous users and performs key actions. They find slow loading issues and fix them before release. This is one of the common functional testing examples where teams may even Hire QA Developer experts to ensure high software quality.

11. Beta Testing

Beta Testing is performed when the software is already complete and is distributed to end users to have it tested in their environment. It is a kind of UAT where the testers are actual end users of the product. Among the objectives of beta testing includes determining performance, usability, and reliability in real life environment before releasing the final product. The product is stable, complete, and fully internally tested when it is released to beta.

Beta testing is not a one size fits all process. Every company tailors the process to their needs. Real users take the software for a test drive in the actual wild environment and contribute their experince, assisting teams enhance their product before its launch.

Beta Testing Process

1. Planning: The team sets beta testing goals, defines the scope, outlines the schedule, and establishes expectations.
2. User Selection: A set of target users is selected according to the product audience.
3. Release: The beta is released to a limited group of users.
4. Feedback Collection: Collect and analyze user feedback to identify issues or areas for further improvement.
5. Closure: Once testing proves satisfactory, the beta software is finished and ready for release.

Example

A railway booking application is given to actual users to test booking and cancellation functions. Users test the app, report bugs, and request new features or changes. Based on this feedback, the product is improved and finalised for release.

12. Compatibility Testing

Compatibility Testing determines whether the software is compatible with various hardware, operating systems, network environments or mobile devices. It ensures that the app looks and performs well on all its touch points of presence. This testing is used to verify whether the users are able to get the same outcome when they are using any device or platform. Compatibility testing is necessary as application and websites these days are not confined to a single or two operating systems but many phones, laptops, and browsers.

Example

A shopping app is tested on mobile, tablet and computer. Testers verify that buttons, images, and text are properly aligned, rendered, and displayed on all screens. They also test it on different browsers to check if it flow the same for all the users.

Conclusion

At Dignizant Technology, we consider functional testing critical to converting business requirements to an enterprise application which is user friendly meets expectations of the customers. Software with functional problems can negatively impact users trust and the growth of a business, which is why our QA professionals are dedicated to testing every feature and function with the utmost care. With the combination of all the types of functional testing at the right stage of development, we assist enterprises, minimizing the risks and providing doable, stable, quality software. With our Software Testing Services you can be sure that your application is working perfectly, meets real user needs and has a chance to succeed in the real world.