Functional testing – Full guide for functional testing

we will explore the subject of Functional Testing, what it is, and why it is important to perform it in any software project. We will cover some subjects, like what methods of functional testing are there, what are the benefits of it and we will share some examples of functional testing.
Functional testing

In this article, we will explore the subject of Functional Testing, what it is, and why it is important to perform it in any software project. We will cover some subjects, like what methods of functional testing are there, what are the benefits of it and we will share some examples of functional testing.

But first, let’s understand what functional testing means:

What is Functional Testing?

A form of software testing known as FUNCTIONAL TESTING verifies a software system against functional specifications and requirements. Each function of the software program is tested using functional tests, which involve supplying the right input and comparing the output to the functional requirements.

Functional testing mostly includes “black box” testing and is unconcerned with the application’s source code. This testing examines the Application Under Test’s User Interface, APIs, Database, Security, Client/Server connection, and other functionalities. Testing can be carried out manually or automatically.

What are the 3 types of Functional Testing?

3 major types of functional testing are as follows:

  • Unit Testing
  • Integration Testing
  • Smoke Testing

What types of Functional Testing are there?

You can see a list of the many functional testing categories below.

Unit Testing

Performed early in the development process, assisting in discovering flaws at this point. This helps avoid incurring greater repair costs for problems later in the STLC.

Methods employed include:

  • Branch Coverage: Testing covers each of the logical connections and outcomes (True or False). For instance, all branches of the path are If and Then conditions in a code If-Then-Else sentence.
  • Statement Coverage: When testing, each statement in the function or module must be visited at least once.
  • Boundary Value Analysis: The test case is then performed utilizing all the prepared datasets. The test data is created for the boundary values as well as for the values that fall just before and just after the boundary value. Days of Month, for instance, may accept values from 1 to 31. As a result, the test case will also be examined for the invalid conditions of 0 and 32 in addition to the legal boundary values of 1 and 31.
  • Decision Coverage: All selection routes are checked during the execution of Control Structures such as “Do-While” or “Case statement.”

Integration Testing

The software consists of two or more unit-tested components that are combined and tested to ensure that their intended interactions occur.

Seen between units, the transmission of instructions, data, DB calls, API calls, and Micro-services processing occurs. No unexpected behavior has been noticed throughout this integration.

Interface Testing

The accuracy of data interchange, data transmission, messages, calls, and instructions between two major parts is evaluated as part of integration testing. Through interface testing, the application’s communication with a database, web services, APIs, or any other external component is evaluated.

System Testing

The system as a whole is tested for compliance and accuracy against the specified requirements after combining all of its components. The integrated system is verified using a Black-Box testing approach.

System testing is carried out in a setting that is close to real life and by real-life usage.

Regression Testing

When a design deviates from an established workflow due to a technology or complete redesign, UX regression, or a step back in the quality or usability of an application’s or website’s user experience, can happen.

Smoke Testing

Smoke Testing is done on the application after development, when a new build is published, to make sure that all end-to-end major functionality functions. It is typically performed on early, unstable versions of an application that were produced during development.

Any important functionality that is found to be broken during testing results in the rejection of that build. The issues must be fixed, and a fresh build must be made for additional testing.

Sanity Testing

Sanity tests are chosen from the suite of Regression Tests to cover the main features of the application. For a somewhat stable application, developers do sanity testing on the fresh release.

An application is prepared for the following level of testing after it properly passes the Sanity Testing.

Acceptance Testing

The end-acceptability users of the application are tested during acceptance testing. The purpose of this testing is to confirm that the produced system satisfies all of the criteria that were established during the development of the business requirements.

It is carried out just after the System Testing and before the program is finally released into the actual world.

Some examples of functional testing

  1. User Login Testing: This tests the user login functionality, including valid and invalid login scenarios.
  2. Registration Testing: This tests the user registration functionality, including validation of mandatory fields, password strength, and email verification.
  3. Payment Gateway Testing: This tests the functionality of the payment gateway, including successful and unsuccessful transactions, handling of various types of cards, and security of sensitive information.
  4. Search Testing: This tests the search functionality of a website or application, including search results accuracy and performance under different conditions.
  5. Shopping Cart Testing: This tests the functionality of a shopping cart, including adding and removing items, updating quantity, and calculating the total cost.
  6. Order Placement Testing: This tests the functionality of placing an order, including shipping options, billing information, and confirmation of the order.
  7. Email Testing: This tests the functionality of sending and receiving emails, including attachments, spam protection, and email formatting.
  8. Data Integrity Testing: This tests the accuracy and consistency of data, including insertion, update, and deletion of data.

These are just a few examples of functional testing, but the specific tests you would perform would depend on the requirements and functionality of the software being tested.

Website Functional Testing?

Functional testing

A website’s functionality is tested using a variety of testing criteria, including user interface, APIs, database, security, client and server, and fundamental website capabilities. It is quite simple to do both manual and automated functional testing with functional testing. It is done to test how well each feature on the website works.

What methods of Functional Testing are there?

Functional testing is a type of software testing that focuses on verifying that a software system meets its specified requirements and works as intended. There are several methods of functional testing, including:

  • Unit Testing: This involves testing individual components or functions of the software to ensure they work as expected.
  • Integration Testing: This involves testing how different components of the software work together.
  • System Testing: This involves testing the entire software system as a whole to ensure it meets all the requirements and works as intended.
  • End-to-end Testing: This involves testing the software system from start to finish, simulating real-world scenarios, and checking for errors.
  • Acceptance Testing: This involves testing the software system to determine if it is ready for deployment and meets the expectations of the end user.
  • Regression Testing: This involves retesting the software after making changes or updates to ensure that the changes did not cause any unintended consequences.
  • Smoke Testing: This is a quick and basic test that is performed to determine if the software is stable enough to proceed with more in-depth testing.

Each of these testing methods has its specific objectives, techniques, and tools. The choice of method depends on the nature of the software being tested, the requirements, and the resources available.

Why Functional Testing should be a priority?

Functional testing is a crucial aspect of software development because it helps ensure that a software application or system functions as intended and meets the needs of its users.

It should be a priority because it helps to ensure the quality and reliability of software, meet user needs, comply with requirements, and ultimately save time and resources.

10 benefits of Functional Testing

Here are 10 benefits of using functional testing:

  1. Improved software quality: Functional testing helps to uncover defects and ensure that the software meets its requirements and works as intended.
  2. Better user experience: Testing the functionality of the software, it becomes possible to identify and address any issues that might negatively affect the user experience.
  3. Increased reliability: Functional testing helps to increase the reliability of the software by verifying that it behaves correctly under different conditions and inputs.
  4. Reduced downtime: Identifying and fixing defects early in the development process, it becomes possible to reduce downtime and minimize the impact of software failures.
  5. Increased efficiency: Functional testing helps to automate and streamline the testing process, resulting in increased efficiency and reduced manual effort.
  6. Improved user confidence: Conducting functional testing, it becomes possible to demonstrate to users and stakeholders that the software is robust and reliable, which helps to build confidence in the product.
  7. Improved product reputation: Delivering high-quality software, it becomes possible to improve the reputation of the product and the company that produced it.
  8. Increased customer satisfaction: Ensuring that the software works as intended and meets the needs of users, it becomes possible to increase customer satisfaction and foster long-term customer loyalty.
  9. Better risk management: Identifying and addressing potential issues early in the development process, it becomes possible to mitigate risks and prevent costly problems down the line.
  10. Improved development process: Incorporating functional testing into the development process, it becomes possible to continuously improve the software and refine the development process, leading to better results in the long run.

Functional testing for Mobile?

Functional testing

User interaction and transaction testing are typically included in the functional testing of mobile applications. Important considerations for this kind of testing include:

  • The type of application is determined by its operational capabilities (banking, gaming industry, social networks, and education).
  • The intended market (user, company, educational environment).
  • The method by which the application is distributed (for example, App Store, Google Play, or direct distribution).

Functional testing for Desktop?

Functional testing for desktop applications involves testing the application’s features and functionality to ensure that it behaves as expected. The purpose of functional testing is to validate that the software meets the specified requirements and functions correctly. This type of testing usually involves the following steps:

  1. Requirements gathering: This step involves understanding the requirements of the application, including the features and functions that need to be tested.
  2. Test case creation: This step involves creating a set of test cases that will be used to test the application’s functionality. The test cases should cover all the functions and features of the application.
  3. Test execution: This step involves executing the test cases on the application and verifying that it behaves as expected. Any errors or defects found during testing should be documented.
  4. Test result analysis: This step involves analyzing the results of the tests and determining if the application meets the specified requirements. If any errors or defects are found, they should be fixed and the tests should be rerun to confirm that they are now working as expected.
  5. Final release: This step involves releasing the final version of the application to the users after it has passed all the functional tests.

What are some Functional Testing interview questions?

Functional testing is the process of evaluating an application in light of the specifications in the requirements document, as the name implies.

Functional testing may be done manually or automatically, but both methods include evaluating the application by giving a set of inputs and identifying or confirming the result/output by contrasting the actual result with the intended result.

Most common interview questions for functional testing

  1. What do you mean when you say “functional testing”?
  2. What essential procedures are covered by functional testing?
  3. What makes functional testing different from non-functional testing?
  4. What distinguishes “Build” from “Release”?
  5. What various test techniques are employed in functional testing?

How to do Functional Testing?

Here’s a step-by-step guide on how to do functional testing:

  • Recognize the Functional Requirements;
  • In accordance with the requirements, determine the test input or test data;
  • Calculate the anticipated results using the chosen test input values;
  • Carry out test cases;
  • Compare the predicted and actual results.

What are some business benefits of Functional Testing?

To release a product that your end consumers would like, it is essential to test your company’s software. Functional and non-functional testing will make sure that your software is risk-free, secure, user-friendly, and simple to upgrade.

Additionally, it lowers the possibility that a significant software error may seriously harm your company.

There are several examples of how software errors have hampered corporate operations in the real world. Nissan removed nearly 1 million vehicles from the market in 2017 because the airbag sensory detectors’ software had malfunctioned.

Due to an unexpected breakdown of its POS (Point of Sale) systems, Starbucks famously had to close up to 60% of its outlets. Baristas were compelled to give away thousands of free beverages, much to the surprise (and joy) of consumers, costing the business millions of dollars in lost revenue.

How to do Functional Testing for a web application?

Any website has to go through testing before going live. Most experienced testers adhere to a set process since it aids in covering all angles.

  • Start the initial steps of functional identification;
  • Create or create the input data by the requirements;
  • Determine the requirements for the output-keeping function;
  • Start running the test case;
  • Examine the findings by contrasting them with what was anticipated.

How to do Functional Testing for a mobile application?

Any mobile app testing process must include mobile functional testing, which verifies that the program functions as it should. check for compliance with design and required standards.

Work together on the testing requirements

That is crucial. There can be no testing strategy without a clear understanding of what needs to be tested. Additionally, there should be no testing without a test strategy.

Although it might seem obvious, it is not the best practice to determine the needs in a vacuum. Which user instructions, integrations, procedures, and displays will be the most crucial will be known by the development team (and the Operations team in a DevOps situation). You may then begin to work on the test plan as a result of that collaboration.

Plan your tests and categorize them according to the importance

We occasionally observe this stage being completely skipped, which is unexpected and concerning. The test plan is not just a dull document where you list the things you already know.

It is a strategy for determining what you will carry out. Instead of writing down the exam strategy, the difficult part is usually the mental gymnastics that go into it.

However, in a nutshell, a best practice testing strategy should include the goals and parameters of the test, the resources needed for the test (including personnel, software, and hardware), as well as a test timeline.

Prioritize and rank the test cases that will be created as part of the strategy as well. Not all tests are equally important to one another.

Identify the automatable tasks

This might equally well be regarded as a component of the test plan creation. But it requires its section since it is so vital to testing and development techniques for mobile apps. Automate as much as you can, to put it simply.

Testing automation shortens the time to market while enhancing software quality. But be wise in your automation choices. This implies that you shouldn’t automate tasks that a manual tester might complete more affordably or efficiently.

Run your tests in actual user environments

More than any other sort of development, mobile app development requires that you discover a means to test in actual user settings. The consequences of losing data coverage or receiving an SMS are not something that web developers need to worry about, but you do.

Naturally, this increases the number of test instances, but that is the nature of mobile. Returning to the earlier discussion about test automation, having it in place will be quite beneficial as you begin to consider the functional requirements under various app scenarios.

Make it simple to submit your findings

The administration of outcomes ought to be one of the simpler aspects of the process, in principle. Although a lot of this relies on the test management systems you choose.

Abstraction and display of test results will be relatively simple with a modern test management system. It will be completed for you, and stakeholders will always have access to a dashboard.


In conclusion, functional testing plays a crucial role in ensuring the quality and reliability of a software product. By thoroughly testing all the functions and features, the development team can identify and fix any issues before the product is released to the market.

This not only helps to enhance the user experience but also reduces the risk of defects and improves the overall performance of the software. Effective functional testing requires a well-defined testing strategy, comprehensive test cases, and robust testing tools and techniques.

By following these best practices, organizations can deliver high-quality software products that meet the needs and expectations of their users.

You can also watch this tutorial about Functional Testing

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