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Top Functional Testing Interview Questions (2023)

Published on Feb 06,2023 156 Views

We all use various software applications as part of our daily life. Even those not working in a company use a variety of applications to complete their routine activities. The use of apps for purchasing goods and services is so common that people of almost all strata of society use them regularly. These apps go through functional testing that the testers conduct. These testers attain their positions after answering various functional testing interview questions. We don’t normally think about the tests they undergo before coming into our hands. 

You can gain much knowledge about functional testing in the Advanced Executive Certificate Course In Product Management offered by reputed institutions. You can access all information about this course on our website. 

Understanding Functional Testing

Every software undergoes testing to ensure it behaves as it should before being deployed. Testers conduct two types of testing on the applications. One is called functional testing, and the other is non-functional testing. Functional testing ensures that the software delivers the desired output without going into internal aspects like speed, security, scalability, etc., that are tested in non-functional testing. Before looking at the most important functional testing interview questions, it is necessary to understand the process and see how testers do it. 

Experts use the black box method to conduct functional testing. It means that the tester is unaware of the internal aspects of the software. The experts only validate the inputs and outputs in the application. Unit testing, API testing and regression testing come under this category. In non-functional testing, the software undergoes tests for parameters like system stability, security and usability. Testers use the white box method for this type of testing. They are fully aware of the internal functions of the application. One of the functional testing interview questions could be about the difference between these two. 

Types Of Testing

Knowing the different types of functional testing could help you answer the functional testing interview questions to the interviewer’s satisfaction. 

Types Of Testing


Unit Testing

In this type of testing, developers check the proper functioning of every unit or component. They do it as and when these are constructed. It helps to ensure that users will get the desired output for a set of specific inputs. It is very important to conduct this test to ensure that the foundation for more complicated features is solid and properly functioning. If a restaurant wants to enable customers to order from their tables using an app, it will require features that help add items to the order. This component undergoes evaluation under unit testing. 

Component Testing

It is another test that checks the proper working of a component. But in this type of testing, there will be the need to input sample data and check the outcome. It will be tested using a stub and a driver. Healthcare applications that help patients schedule appointments with doctors must show nearby hospitals or healthcare centres. It will be tested by using the user profile as the stub and the available appointments of the doctor as the driver. Asking you to define this testing could be one of the functional testing interview questions

Integration Testing

Modules and components undergo an evaluation to ensure that they function properly. But they must also function together in an application. Quality experts check their functionality as a group in integration testing. In many cases, the components are built separately by different developers. This makes it necessary that you test them for functioning together. A banking application will have the facility to transfer money from one bank account to a different account of the same person. This must happen smoothly and for this, conducting integration testing is necessary. 

Also Read: Top 13 Skills For A Great Product Management Career

System Testing

As the name suggests, this test ensures that the system functions and delivers what users expect from it. This test is also known as end-to-end testing, as it checks all the business and functional requirements of the software. In this case, the testing environment must be a replica of the production environment. Testers use the white-box method, where there is no involvement of testers in the development of the system. Knowing this in detail can help you answer the functional testing interview questions correctly. 

Regression Testing

The addition of a new feature or making other changes to software can upset its functioning. It means you must test it after integrating the new features to ensure that the system functions properly after the alteration. The application’s stability and functionality go through testing using regression testing. Experts often automate this test due to its work-intensive nature. Many apps allow service providers to add new promotions on top of existing ones. Regression testing helps ensure that the other functions are not disturbed due to adding the new feature. 

Sanity Testing

Testing teams do this test after fixing bugs or adding new codes. While regression testing ensures that the system functions after making changes, sanity testing checks the functionality of the particular unit where changes have been made. The difference between these two can be one of the functional testing interview questions you may face as a candidate in the product manager interview

Smoke Testing

It is the QA team that conducts the smoke testing. In this test, only the core and critical functionalities of the software are tested to ensure that they function as desired. It is an acceptance test in the early stages. Once the product undergoes this testing successfully, it is ready to go to the next state. This testing will ensure that the software performs its job to the required level. 

The Advanced Executive Certificate Course In Product Management is ideal for learning everything about functional testing. Attending the course is probably the best way to answer all functional testing interview questions and proceed to the next step. The course details are available on our website. 

Top Functional Testing Interview Questions

Top Functional Testing Interview Questions

  1. Why is functional testing very important in the development of software applications?

The first reason for conducting this test is to ensure that the customer gets high-quality products. The QA team uses functional testing to ensure that the product offers the functionalities mentioned in the Software Requirements Specification and that the application functions as desired by the user. This testing ensures that the features that affect user experience are functioning as required. It is a way for testers to check the software and give valuable feedback to the developers on improvements that can be made. 

  1. What are the types of functional testing?

It is one of the functional testing interview questions that are most likely to be faced by a candidate. Functional testing is a set of tests of which all or some will be used in all software development processes. Some of the methods may be given preference over others depending on the application being developed. The types of functional testing are unit testing, component testing, integration testing, system testing, regression testing, sanity testing and smoke testing. 

  1. Explain the functional testing process?

Understand the requirements – It is necessary to understand the business requirements before undertaking functional testing. You must document the specifications and get everything clarified before starting the process.

Prepare a test plan – Planning the test well is crucial for the success of the test. Concentrating on the objectives of the test will help testers plan and organise the test well. 

Write a test case – You must write a test case keeping in mind all test scenarios and the software requirements. 

Create input data – Testers must create input data to test different functionalities of an application. This is referred to as test input data. 

Execute test cases – Conduct test cases using the above test input data.

Compare results with requirements – Once the test results are obtained, testers must compare these results with the desired outcome. This will decide whether the product has passed or failed the test. 

Log defects – Testers must record the variations between actual results and the desired outcome. This is known as logging the defects, and it helps developers correct the faults. 

  1. What are the differences between functional and non-functional testing?

Answering this functional testing interview question is essential for moving up to the next level in the interview. A functional test checks whether all the functions or features of an application are working as desired. The non-functional testing is done to test the internal factors like stability, security and reliability of the software system. While business requirements are considered in functional testing, it is the customer expectations and performance requirements that are tested in non-functional testing. While customer feedback in the former case helps in reducing risk, such feedback in the latter testing method allows for the improvement of the product. 

Also Read: Top Product Management Exercises For A Career Growth

  1. What are the differences between functional testing and unit testing?

Both these tests are crucial for the proper performance of the product. While functional testing helps to ensure the overall performance of the software, unit testing is done to check the working of each component of the system. Unit testing helps to find out issues that come up in modules, while functional testing identifies problems that prevent the application from working properly. As there are numerous tests to perform in functional testing, there is a possibility that some issues may escape notice. This is not the case with unit testing. 

  1. Explain the difference between functional and regression testing?

Testers conduct functional testing to make sure that the final product performs as promised by the company. Regression testing is conducted after the release of the software to ensure the proper working of the system after adding fresh codes, making improvements and fixing bugs. 

  1. What is ad-hoc testing?

As the name suggests, this is a test that quality teams conduct randomly to ensure the proper functioning of the product. There are no plans, documentation or test design for this type of testing. Developers do this test when there is little time between the development and release of the product. The test is conducted randomly in certain parts of the software to ensure it functions properly. 

  1. What is the difference between release and build?

Build refers to a standalone form that results once the codes are developed. The development team hands over the build to the testing team to make sure that all functions are proper. If some defects are found, the build is rejected, and another one must be generated. A release, on the other hand, is a final product that is handed over to the customer after testing and certification.

  1. How do Alpha and Beta tests differ?

Alpha testing is performed by the internal quality assurance teams of the company. This internal acceptance testing is done before releasing the product to the customer. A few clients or users outside the company do the Beta testing. Alpha testing does not check the security or reliability of a product thoroughly. In the Beta testing, the users check the availability, security and robustness of the product. While the black box and white box testing are performed in Alpha testing, only the black box method is adopted in Beta testing. This is one of the important functional testing interview questions that candidates can expect to face. 

  1. What are the test techniques used in functional testing?

There are two different techniques in functional testing, namely requirement-based technique and the business process-based technique. The former technique prioritises requirements based on risk factors and ensures covering all critical test paths. The latter examines the business process. This requires adequate knowledge of the business processes. 

One can learn many more functional testing interview questions and their detailed answers in the Advanced Executive Certificate Course In Product Management. The details of this programme are available on our website. 


Functional testing is a critical activity that every software development company must conduct. It ensures that the product that they deliver adheres to the best quality standards. Such testing also makes sure that customers get what they desire and have a good experience with the product. This makes it essential that the experts who conduct the tests must be thorough in the subject and have all the skills needed for the job. Asking important questions on the subject confirms the expertise of the candidate, and the company can rest assured of having picked the right person. 


More Information:

Theory Of Product Pricing and Costing: Meaning, Fundamentals & Frameworks

Optional Product Pricing: What Is It And How To Use It?

What is Product Analytics: A Complete Guide

Data Handling: Meaning, Frameworks & Examples


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Top Functional Testing Interview Questions (2023)