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Functional Testing Types and Benefits

Updated: Oct 24, 2023

As the name suggests, functional testing tests multiple aspects of the software product. Let us understand in depth about what is functional testing? The main job of Functional Testing is to check whether each application feature works as per the software requirement. It is a kind of Black Box testing where the tester does not know the internal system logic, and the tests are based on the specifications of the software component under test.


While performing Functional Testing, the internal program structure is rarely considered, and the Functions are tested by feeding inputs and evaluating the outputs.


Proper application of Functional Testing not only delivers huge benefits to the development process but also enhances the communication between analysts, developers, and testers. Functional testing is very diverse and has to be performed on all testing levels since every level has a different point of focus.


So, without much further discussion, let us jump to the functional testing types and categories and how it is useful to software development companies.


Significant Categories of Functional Testing Services


Functional testing is diverse and majorly focuses on the results of processing and has no relation with the mechanism, and rather, it focuses on whether the application satisfies the basic minimum user experience. Functional testing can be majorly categorized, and the different functional testing types are as follows.


1. Component Testing-

Component Testing, also known as Module Testing, assesses a part of the software in isolation from the broader system and tests individual parts of the system. Component Testing is performed by testers in a black box format to validate individual objects or parts of the software.


Broadly speaking, when a module or a component of a system is independently tested by giving inputs to verify its expected output, thus validating the behaviour of the individual component, is the main function of Component Testing.


Component Testing is performed by the testing team immediately after the developers are done performing Unit Testing. The major functionality of the components of the system is tested in phases of entry criteria, and exit criteria, where in entry minimum number of components are to be included in the Unit Test, which should be developed and unit tested.


Secondly, in exit criteria, the functionality of all the components is checked, and the presence of any critical or high, or medium severity is observed.


2. Unit Testing-

Unit Testing is done on the individual parts of an entire software to check whether they work properly on their own or not. Unit Testing ensures that the inputs results in the desired output, thus validating the function of the unit.


Unit Testing is done by developers in a white box format to verify how the program modules execute. This type of testing provides a foundation for more complex integrated software as the smallest functional testable unit of code is tested during Unit Testing.


Since this testing is performed in the earliest stages of development, it helps in identifying defects in the initial phase and saves the higher cost of fixing the defects during a later stage. The techniques used in Unit Testing are Branch coverage, Statement coverage, Boundary Value Analysis & Decision Coverage, and tools generally used are Junit, jtest, JMockit, NUnit, etc.


3. Integration Testing-

Integrated testing is the most common type of Functional Testing, which is performed as automated testing. QA professionals, through Integration testing, check whether individual modules of the code work together as a group or not.

Here two or more unit-tested components are integrated and tested to validate the interaction between the components is stable and as expected. This test confirms that each module that is working fine individually does not show any kind of bugs when integrated.


Generally, the developers perform both black box and white box functional verification extensively and check if the communication of commands, data, API calls, DB calls, etc., is happening between the units and there is no behavioural issue observed.


The main purpose of this testing is to make data and operational commands flow between the modules to check that the modules act as part of the entire system and not like individual components.


4. Smoke Testing-

Smoke Testing is a kind of acceptance testing that is carried out basically in the initial stage to provide an initial check of whether the critical functionality and build of the new software are stable or not.


QA team performs further testing on the stable build and checks the new features and functionality, and then regression testing is done depending on the situation. This type of testing determines the state of the product quality and checks the readiness of the developed product for more extensive further testing.


The main aim of this testing procedure is to verify that the critical functionality of the system is working fine. If the Smoke Test fails, i.e. if the system is not stable, it is rejected and forwarded to the development team for fixing the bugs and creating a new build. If the Smoke Testing is found successful, then the application is forwarded to the next level of testing.


5. Sanity Testing-

In general, Sanity Testing is a type or a subset of Regression Testing. When only minor modifications are made to a new build, Sanity Testing is done instead of doing a full regression test.


The main purpose of the Sanity Test is to highlight that the modifications or the addition of new features to the software have fixed the problem, and no further issues have been introduced by the fixes.


Sanity Testing is unscripted and provides a gate check that a build is ready for more testing, and it specifically targets the area where a code change has occurred.


6. User Acceptance Testing-

From the inception of the software development, it goes through multiple testing procedures from developers and testing teams. The ultimate goal of this effort is to provide stable working software.


User Acceptance Testing (UAT), as the name suggests, aims to provide the acceptance of the application by the end user. It is the last phase of the software testing journey, which testifies that the developed software fulfils all the requirements that were asked of the client and meets the expectations.

User Acceptance testing involves the review of the entire software end-to-end experience and feature complete application flow and does not focus on the functionality of the specific features.


The main purpose of UAT is to check how well the application or software will perform in normal conditions when the end user uses it with a fresh mind and whether it is easy to follow and fulfils their requirements.


7. System Testing-

System Testing is a Black Box testing technique that aims at testing the system when all the components of the system are combined. It is performed in an almost real-life environment and according to real-life usage just before User Acceptance testing in the Software Testing Life Cycle.


System Testing is done by testers and developers who were not involved in the program development, and they check whether the system is meeting the technical, functional, and business requirements as set by the stakeholders.


8. Regression Testing-

In any working software, whenever the developers implement any change or modification in the code, there is a high chance that the updates may introduce bugs and cause a change in the working software. Regression testing is done to ensure that a change or modification does not alter the functionality of the software.

Its main role is to identify the bugs or any modification which may have been introduced accidentally and make sure that the bugs which were removed earlier continue to remain dead.


Thus, keeping the product stable while making changes to it. There can be three approaches for Integration testing which, are the Top-Down approach, Bottom-Up approach & Hybrid approach.


Key Benefits of Functional Testing


Functional testing mainly focuses on producing an error-free product by ensuring that all the requirements from the stakeholders are met and are as projected.

Let’s list down how functional testing services improve the quality of the product and ensure the safeguarding of a software application:

  • It makes sure that the client or end-user is contented.

  • It produces defect-free and flawless software.

  • It makes sure that all the needs are met.

  • It makes sure of the precise working of all the product features.

  • It makes sure that the software works as anticipated by the client.

  • It makes sure of the software's security and safety.

  • It enhances the overall quality of the software product.

  • Its reporting and analysis lead to enhancements in the software

  • The risks and losses allied with the software are trimmed down.

Moving Forward with Functional Testing


Functional testing, as described above, is focused only on providing bug-free software or product which works exactly as it was intended. It is an intrinsic part of the software testing process that plays a crucial role in transforming the requirement of the stakeholder and converting it into a stable bug-free application or software.

Functional testing makes sure that all elements of a software work and function effectively. So, investing in functional testing might mean the variance amid producing a profit and a loss since it is much less expensive to address bugs beforehand release than after.


At PerfectQA, we offer excellence in delivering high quality software by enabling Testing and Quality Assurance (QA) services. Our testing and QA services, which include automated functional testing services, will assist you in controlling your product's entire life cycle, cross-checking every stage of software development, and providing trusted product quality to the diverse set of users and important stakeholders.

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