What Is Functional Testing? Find Out All About The Types Of Functional Testing

What is functional testing? According to the functional testing definition, software testing is used to verify the software system against applicable requirements or specifications. The main objective of performing a practical test is to examine each software application function by providing relevant input and checking the output against functional requirements.

Functional testing mainly involves black-box testing, and it is not relevant to the source code of the application. Functional testing in software testing checks user interface, API, database, security, client-server communication, and other application functionalities under test. It can be performed either manually or by using automation testing.

Difference between functional and non-functional testing

Functional testing describes the process of testing, whereas non-functional testing is used for checking performance, reliability, usability, etc.

Let’s have a look at various parameters on which we can compare these two types of testing:

ParametersFunctional TestingNon-Functional Testing
ObjectiveVerified software actions are carried out.The performance of the software is verified.
Area of FocusConcentrates on user requirements.Concentrates on user expectation.
Ease of Testing Black box testing is easy to execute.White box testing is easy to implement.
FunctionalityWhat the product does is described.How the product works are described.
ExecutionPerformed before non-functional testing.Performed after functional testing.

What is functional testing in software testing, and how is it performed?

Below provided is a step-by-step instruction to perform functional testing using a functional tester:

  1. Understand the applicable requirements.
  2. Recognize test input or test data based on needs.
  3. Calculate the predicted outcomes with selected text input values.
  4. Execute test cases.
  5. Analyze actual and computed expected results.

What are the different types of functional testing?

The functional testing definition states it has several categories, and the usage of each could be based on the scenario. The most famous types of functional testing concisely discussed below:

Unit testing:

Unit testing is done by a developer who writes different code units related to or unrelated to achieve a distinct functionality. It usually involves writing unit tests that describe each division’s methods and confirm those when the necessary parameters are passed and its return code is expected. Code coverage is an integral part of unit testing where test cases are required to exist to cover the below three:

  1. Line coverage
  2. Code Path coverage
  3. Method coverage

Sanity testing:

Testing performed to ensure all the significant and essential functionalities of the application/system are working is known as Sanity testing. 

Smoke testing: 

The testing performed after each build that is released to build consistency is known as smoke testing. 

Regression tests: 

The testing conducted to ensure that adding new code, enhancements, and bugs are not breaking the existing functionality for making any instability and still works according to the specs is known as a regression test. The regression test is not required to be as comprehensive as the actual functional tester but should assure just the amount of coverage for certifying that functionality is stable.

Integration tests: 

When the system depends on multiple functional modules that work independently but are combined to achieve an end-to-end scenario, they must be used logically; validation of such techniques is called integration testing.

Beta/Usability testing: 

The product is shown to the customer in a production-like environment and detects the product. It is significantly comparable to user acceptance testing.

What are Functional testing techniques?

The primary approach to testing could be categorized into two broad categories:

Positive testing: Positive tests are happy path tests performed to guarantee that the product meets essential requirements for customer usage.

Negative testing: Negative scenarios ensure that the behavior of the work is proper when it is subjected to an expected data.

What is functional testing?

Now let’s look at the subcategories of these two different methods of functional testing:

End user-based tests

The system under test contains many components that produce user scenarios when linked together.

Equivalence tests

The test data is split into various partitions called equivalent data classes. Data in each section must act in the same way; therefore, only one condition is required to be tested. Similarly, if one situation in division stops working, none of the other states will do.

Boundary value tests

A boundary test indicates that data limit to the application and confirms how it functions. If Input given is beyond the limited values, then it is supposed to be negative testing.

Decision-based tests

If a specific condition is fulfilled, the decision-based test focuses on the idea of potential outcomes of this system.

Alternate flow tests

An alternate path test is used to confirm all the possible ways that exist other than the main floor to achieve a function.

Ad hoc tests

The above techniques of the test reveal the majority of bugs and are an excellent way to find any errors that are not observed earlier.

Advantages of functional testing

Functional testing is essential as it verifies that the system is set for or release, and it is error-free.

Now let’s have a look at some of the benefits of functional testing using functional tester:

  1. It provides a replica of the existing system, i.e., it is a replica of what the product is in the real environment. 
  2. It does not run on any hypothesis about the structure of the system.
  3. Functional testing assures delivery of a high-quality product designed to meet customer requirements and make sure that the customer’s needs are fulfilled.
  4. It guarantees to deliver a bug-free product with all the functionalities running as per customer requirement.
  5. Risk-based testing is required for minimizing the chances of any e risk in the product.

We gained a brief insight into what is functional testing? The functional testing definition indicates it is a method of testing functionalities off the system, and it guarantees that the system is running as per the functionalities defined in the business document. The goal of functional testing is to check whether the system is functioning correctly.