Functional Testing: A Complete Guide For Beginners!

What is Functional Testing? 

Functional testing that evaluates whether a system, application, or website is carrying out its intended functions correctly is known as functional testing. To make sure everything is functioning as it should, this involves testing the system's features, user interface, data handling, and other components. Functional testing seeks to find any system flaws or errors so they can be fixed before the product is made available to end users. Functional testing is a crucial step in the overall software development process and can be carried out manually or automatically using testing software.

Difference Between Functional Testing VS Non-Functional Testing

How Functional Testing Is 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.

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, which are- unit testing, smoke and sanity testing, regression testing, integration testing, and usability testing. These most famous types of functional testing concisely discussed below:

1. 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:

• Line coverage
• Code Path coverage
• Method coverage

2. Sanity Testing

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

3. Smoke Testing

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

4. Regression Tests

Software Regression testing is 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.

5. 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.

6. 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.

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.

Now Let’s Look at the Subcategories of These Two Different Methods of Functional Testing:

1. End User-Based Tests

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

2. 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.

3. 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.

4. Decision-Based Tests

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

5. 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.

6. 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 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 services is to check whether the system is functioning correctly.