Functional Testing : Definition, Types & Examples

Functional testing is a type of software testing that validates the functionality of an application by means of automated tests. Functional testing does not ensure that all data input, output, and internal structures are working correctly. It only checks if the end product meets its required requirements.

A functional test is a test that checks whether a piece of software meets its intended functionality. Functional tests include unit testing, system testing, integration testing, and acceptance testing. A basic example of a functional test is to see if an application works properly when you click on the home button on your smartphone.

Functional Testing Definition

In general, the definition of functional testing is a test that identifies defects before they cause an error or result in failure. However, this definition is just one way to look at it. In reality, functional testing includes a lot more than just finding bugs and inconsistencies in software functionality.

As per Wikipedia, the definition of functional testing is:

Functional testing is a quality assurance (QA) process and a type of black-box testing that bases its test cases on the specifications of the software component under test. Functions are tested by feeding them input and examining the output, and internal program structure is rarely considered (unlike white-box testing). Functional testing is conducted to evaluate the compliance of a system or component with specified functional requirements. Functional testing usually describes what the system does.

What is functional testing?

Functional Testing is the process of verifying that a software application has the functionality it needs according to its requirement specification. In functional testing, each function is tested by giving it a specific value, checking the output, and verifying that its behavior matches what we expect.

Functional testing, also referred to as black-box testing, is a type of software testing where the tester knows little about the internal structure or workings of the item being tested and mainly focuses on whether or not end users have access to what they need.

Functional testing is often referred to as black-box testing because it focuses exclusively on application specification rather than actual code. Tests are performed without knowledge of the system’s internals, so a tester has no need to know the programming language or implementation details.

Why We do Functional Testing?

Every application being developed has some functionality. It is the responsibility of testing to ensure that the application’s functionality meets business requirements, and we are achieving whatever we intended through the design of this software.

Functional testing ensures that users can access all of the expected features in an application. Functional tests are written from a user perspective (not a programmer’s perspective) and include functionality such as login, search, shopping carts, and so on.

Functional testing is not concerned with finding defects; it is only focused on whether or not an application’s functions work or how users can do something in the system. It does not test for corner cases or error handling routines.

Functional testing does not test the application’s security features, just the functionality. Black box testing is designed to test the specification of an application and not its internal structures or workings.

Example :

An older system may not appear to work at all when you enter an incorrect delivery date on a new order. A tester would be looking for this type of behavior in functional testing and would fail the test if the application returned an error message or did not process the order at all. In other words, functional testing is focused on specific results and behaviors of the system under test as defined in a requirements specification or user story.

Functional testing is conducted by business analysts, users who use applications regularly, testers, and others with specific knowledge of the application’s business requirements.

Different Types of Functional testing

Different types of functional testing are described below:

Unit Testing – This type of functional testing is performed by the programmer who creates unit test cases to ensure that each function does what it is supposed to do given a specific input. Automated unit tests (unit tests written automatically by an IDE or other tool) are used here for this purpose when possible.

Test Scenario Testing- If you are using Agile methodologies to develop your application, then this type of functional testing is important because it ensures that the development team has included all the necessary business requirements. Test scenario testing is often a collaborative effort between programmers and testers.

Test Case Design- This type of functional testing involves designing tests that will validate each requirement in an application’s user story or task description. Test cases are then written for each requirement in a test plan.

Component Testing – This type of functional testing is used to ensure that the major components of an application (such as a website’s logon capability) work correctly. Component tests are usually based on programming code but do not require knowledge of the programmer’s coding language.

Smoke Testing– Smoke tests are quick, informal tests performed at the end of each iteration (a period of development). Smoke testing verifies that the latest code build works as expected based on previous test results.

Integration Testing– This type of functional testing is often used when several components or systems are being integrated together to form a larger application. Integration tests ensure that the different parts of the application work together according to specifications, and they can determine whether or not errors occur during integration between the various parts and modules.

Regression Testing– Regression testing is also called “retesting.” It is used to determine if an application that previously passed functional tests still works correctly after a change has been made.

Sanity Testing– Sanity testing is a quick test that is done during the early stages of development to make sure there are no show-stopper defects.

System Testing– System testing is the most formal type of functional testing. In this process, the system under test is put through its paces to determine if it works as expected based on the requirements specifications.

User Acceptance Testing– UAT stands for “user acceptance testing.” This type of testing is conducted as a final check of an application before it goes into production (the phase when the software is actually given to users).

User acceptance testing is conducted by a representative of the people who use an application. In some organizations, this may be a business representative or a customer.

White box testing- White box testing focuses on the internal structure of an application.

Black box testing- Black box testing attempts to test application functionality without knowing how it was programmed or designed.

Grey Box Testing- This type of testing focuses on both the application’s structure and its functionality.

Static Testing- Static testing refers to functions that are tested at compile time (before the application is run). This type of testing uses many visual inspections and requires knowledge of programming languages.

Dynamic Testing- Dynamic testing refers to functions that are tested while executing the application. This type of testing usually involves placing various inputs into an application and then validating whether or not expected results occurred.

Database Testing- This type of functional testing is performed on databases by creating test data and then attempting to execute a variety of queries to ensure that the database works as expected.

Ad-hoc testing- Ad hoc testing is done without formal test plans or test cases.

Recovery Testing- This type of testing is conducted to verify that backups are working correctly and data can be recovered in the event of a system crash or other catastrophic event.

Alpha testing- Alpha testing is done before beta testing to determine if a product has all the necessary features and works correctly. Alpha tests are typically conducted by employees of the organization developing the software or by third-party testers.

Beta Testing- Beta testing is often used when an application is about to be released to customers for evaluation purposes. The application is tested by real users, and results are analyzed to determine if any necessary changes need to be made before the application is released.

API testing- API testing is used to validate that an application programming interface (API) works as expected.

UI testing- UI testing is used to validate that a user interface works as expected.

Production testing- Production testing is used to validate that an application works as expected in a production environment.

What are the advantages of Functional Testing?

Testing is always necessary to see if the thing being tested will work as desired. We can test functionalities, applications, and even websites with these types of tests which we have just discussed above. Functional testing is always good because there are many benefits that could be gotten from it.

The first advantage of conducting this type of testing is that it can find bugs if there are any in the program or website we are going to use. Even though many developers will say that there is no such thing as bug-free software but this type of testing can really help us minimize the effect and it could also make sure that the program won’t have too many issues when used.

Another advantage of functional testing is that is can be changed. If our website or application needs to have a different function then it will still be possible since we are only testing its functionalities.

It also helps us validate user requirements on what they need the program/website to do. This makes them satisfied once they see how exactly the software does and is going to work for them.

Finally, functional testing can be done automatically with the use of automation tools that are available in the market today. This is useful for us especially if we have a lot of programs and websites to test since this could save up time and money because it doesn’t need a human being to do its job. Automation also helps lessen our chances of making mistakes especially when it comes to repetition.

What are the challenges of Functional Testing?

No matter how great functional testing is there are also some disadvantages that could be gained from doing this type of test. One of which is the things that could make it fail and incorrectly perform its work. Even though we may not be able to eliminate these factors, we can lessen them and know how to deal with them.

One of the biggest challenges that functional testing could have is its speed. Since it needs to test each function one by one then a lot of time will be consumed. This will delay the process of creating or updating our program/website if we always need to use it.

Another challenge is on the skill of its tester or team developing it. There are different levels in order to test a software/website and this could be difficult for many especially if they do not have the ability to handle them.

It also depends on what type of testing we need to use. We may only have one functional test but in order to make it work, we have to use the right ones according to our situation.

What are the best practices of Functional Testing?

There are a lot of best practices that can be done while conducting this type of testing and they could really help us out especially if we know and understand them. It’s always good for us to always keep these practices in mind so we would know what to do whenever a problem arises.

One of the most important ones is that we should have great communication skills at all times. Since this type of testing will involve many people, it’s important for everyone to be able to talk and share their thoughts with each other if they need to enhance the process.

We should always follow a plan and know what needs to be done for the software/website to work perfectly. This will help us avoid any rushing issues to occur and if it already did then we can fix them immediately.

Another best practice that is useful here is to have reported everything that was tested during each run so technicians or managers can check it. This will help them to have an overview of what was going on and how they could lower down the risks for bugs to occur.

It’s also important for us to make sure that we are aware of all changes and updates that might affect the program/website. Making sure about this could save up time for us since we won’t be doing a lot of tests that are not needed.

We also have to make sure that our program/website is stable and will not crash the moment it’s launched. This could lower down its reputation from potential users in case this ever happens which means that sales would decrease as well or even stop completely.

What is the future of Functional Testing?

Since functional testing is being used by many people, there are also some new additions that have been added to it. This would help us make it more efficient and better than before.

Technology always changes every single day and this is no different when talking about functional testing since they can now do more in one run. This means that we will not need to always do it over and over again like before.

There are also a lot of new tools and software’s on the market for us to use so be sure to check them out. When using functional testing, make sure to check them out first since they could save up a lot more time and energy when doing it.

These practices would surely help us with doing our jobs in testing a program/website. They are very effective and could save a lot of time for us since they work fast. It’s also important for us to keep our knowledge about how functional testing works so we can be able to use it properly.

Conclusion

Functional testing is a vital part of software development because it’s the process that simulates how your application will perform in real-life scenarios. The goal is to identify any glitches, bugs, or other errors before it hits the market so you can make adjustments and prevent costly delays.

Let me know what you think about functional testing below in the comments section.