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Table of contents
1.
Introduction
2.
Easy Level Interview Questions
2.1.
1. What is functional testing?
2.2.
2. Explain the purpose of Functional Testing?
2.3.
3. How does Functional Testing work?
2.4.
4. Why Functional Testing is called Black-Box Testing
2.5.
5. What is the role of a functional tester?
2.6.
6. What is the difference between functional and non-functional testing?
2.7.
7. Is functional testing manual or automation?
2.8.
8. What do you mean by Black Box Testing?
2.9.
9. What are the different methods for Functional testing?
2.10.
10. What is the use of a Traceability Matrix?
2.11.
11. What do you mean by Adhoc Testing?
2.12.
12. What is Acceptance Testing?
2.13.
13. What is GUI testing?
2.14.
14. What is Stress Testing?
2.15.
15. What do you understand by the term Fault?
2.16.
16. What do you mean by Bug Leakage?
2.17.
17. What do you understand by the term Bug Release?
3.
Medium-Level Interview Questions
3.1.
1. What is the difference between Build and Release?
3.2.
2. What is the use of Functional Testing?
3.3.
3. What are the advantages of Automation Testing?
3.4.
4. What do you understand by Alpha testing and Beta testing?
3.5.
5. What is the disadvantage of Functional testing?
3.6.
6. What are the different coverage criteria?
3.7.
7. What are the recommendations for writing good test cases?
3.8.
8. What is Random Testing?
3.9.
9. What are the different Functional Testing tools widely used?
3.10.
10. What is Defect Removal Efficiency?
3.11.
11.What do you understand by the term Defect Life Cycle?
4.
Hard-Level Interview Questions
4.1.
1. What is the difference between functional and non-functional testing?
4.2.
2. Explain different types of Functional Testing.
4.3.
3. What are the steps carried out during Functional testing?
4.4.
4. How should one prioritize the key factors when conducting Risk-based Testing?
4.5.
5. What do you understand by Retesting and Regression?
4.6.
6. What are Defect Severity and Defect Priority?
5.
Conclusion
Last Updated: Mar 27, 2024

Top Functional Testing Interview Questions (2023)

Introduction

Functional Testing is a type of Software Testing in which every feature of the software application is tested for the desired output. If the software system has all of its applications running as expected, then the software is considered Functionally tested software. Each function is provided a set of inputs. It is then determined by comparing the obtained results with the actual results. At various stages of software development, Functional Testing is being done.

Top Functional Testing Interview Questions (2023

Functional Testing is also called Black-Box Testing because the testers determine the result only by comparing the inputs and outputs. Only the program is checked, not the system. It even helps in understanding whether the system software is ready to deploy live. Let us discuss some of the most-asked Functional Testing Interview questions.

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Easy Level Interview Questions

Here is a list of some basic functional testing interview questions.

1. What is functional testing?

Ans: Functional testing is a software testing technique that assesses a software application's functionality by testing its individual features or functions and it verifies that the application performs as expected according to the client requirements.

2. Explain the purpose of Functional Testing?

Ans: The purpose of Functional Testing is to validate that a software application's individual features and functions work as intended. It tries to ensure that the software meets user requirements and it functions properly under different conditions before it is deployed.

3. How does Functional Testing work?

Ans: There are predefined test cases that are executed during the test execution phase of functional testing. During this phase, inputs are provided to specific functions of the software applications, and the outputs are compared with the expected results. Any errors are documented properly and the stakeholders are notified to ensure they are fixed quickly.

4. Why Functional Testing is called Black-Box Testing

Ans:  Functional testing is a Black Box software testing in which it focuses on whether the system is providing the desired output or not. It just checks whether the software is generating the output to satisfy the requirements.

5. What is the role of a functional tester?

Ans: The role of a functional tester is to carefully assess software applications by executing the predefined test cases and scripts. They verify that the software functions according to specified requirements, identifying defects and discrepancies between expected and actual outcomes. A functional tester must have effective communication skills to delegate the error details to the product stakeholders properly.

6. What is the difference between functional and non-functional testing?

Ans: Functional Testing: It is a type of testing in which each component in the software is being tested by providing inputs and comparing between the outputs received and the desired outputs.
Non-Functional testing: It is a type of Testing that looks after the system's performance, stability, security etc.

7. Is functional testing manual or automation?

Ans: Functional testing can be either manual or automated. Let's discuss both of these techniques.

  • Manual Functional Testing: In manual functional testing, the testers manually interact with the software applications and execute test cases, input data, and observe the outputs.
     
  • Automated Functional Testing: Automated functional testing involves using testing tools and scripts to perform test cases automatically. It is more effective for complex software applications, where manual testing will take a lot of time.

8. What do you mean by Black Box Testing?

Ans: Black Box testing is a technique where testing is only done on the basis of requirements and specifications. No importance is given to the internal structure of the system or its implementation.

9. What are the different methods for Functional testing?

Ans: Functional Testing aims at providing the expected results for the user and works as expected. These are the methods in functional testing:

  • Unit testing
     
  • Integration testing
     
  • Smoke testing
     
  • Regression testing
     
  • System Testing
     
  • User Acceptance Testing

10. What is the use of a Traceability Matrix?

Ans: In manual testing, a traceability matrix is a valuable tool that is used for maintaining links between various elements of the testing process. Let's discuss some of its use cases.

  • Test Case Management: It serves as a centralized document for managing and organizing the test cases. Testers can easily access and update test cases according to the project requirements.
     
  • Defect Tracking: When defects are identified during testing, the Traceability Matrix can link them to the specific test cases that revealed them.
     
  • Change Management: In case of changes or updates to project requirements, the Traceability Matrix helps identify which test cases need to be modified or added to accommodate these changes.

11. What do you mean by Adhoc Testing?

Ans: It refers to the type of testing in which there is no planning done, and a part of the application is randomly checked to find defects. It is majorly done when there is a time constraint. It doesn't focus on the requirements of the application.

12. What is Acceptance Testing?

Ans: Acceptance testing is done either by the end-user or the client. It helps understand whether the application is working as expected and is fulling the demands of the end user. If Accepted, the application is ready for the production phase.

13. What is GUI testing?

Ans: GUI testing is a software testing technique that evaluates a software application's graphical elements and user interactions. It verifies that the functionality of user interface components, such as buttons, menus, forms, and navigation.

14. What is Stress Testing?

Ans: Some stress is given to the application, and the point just before the system crashes is called the stress point. It helps in understanding the performance and capability of the application.

15. What do you understand by the term Fault?

Ans: Fault can be regarded as a situation where the system is failing while performing a specified function.

16. What do you mean by Bug Leakage?

Ans: It refers to a condition where the Bug is identified by the end user. This bug was not able to be found by testers while testing the application.

17. What do you understand by the term Bug Release?

Ans: It is a condition when a bug of low severity is being released in a specific known software version. It was already known by the testers/developers.

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Medium-Level Interview Questions

Here is a list of some intermediate functional testing interview questions.

1. What is the difference between Build and Release?

Ans: Build: It refers to the file that is a part of the application that is given to the testers to test the functionality of the system. Testers may reject the file if the build file does not pass the decisive list.

Release: It refers to the software application that has completed the testing and development phase. It will give to the user. It may consist of several builds with it.

2. What is the use of Functional Testing?

Ans: Functional testing helps in determining the software quality and whether the software is performing as expected. This includes

  • It helps in determining the quality of the application and whether the application is fulfilling the stated requirements or not.
     
  • It helps in obtaining bug-free code which is scalable.
     
  • It gives ideas to the developers on where to improve the software and make it bug-free.
     
  • It checks the readiness of the software to the user and hence improves user experience.

3. What are the advantages of Automation Testing?

Ans: The following are some advantages of automated testing:-

  • Efficiency: Automated tests can be executed faster than manual tests, as the human interaction is minimal.
     
  • Repeatability: Tests can be run consistently, ensuring the same steps and conditions are applied for each test cycle.
     
  • Coverage: Automated tests can cover many scenarios, including repetitive and complex ones that are harder for humans to perform.
     
  • Continuous Integration: Automated testing fits well with CI/CD pipelines, allowing you to test as changes to the code are pushed.

4. What do you understand by Alpha testing and Beta testing?

Ans: Alpha Testing: It is done by the team of developers/testers before the application is launched. All the bugs detected during this process are being cleared immediately. It is done prior to  Beta testing.

Beta Testing: After the Alpha testing is concluded, Beta Testing comes into play. Here a group of individuals that are included in tester/developer teams tests the software. It helps in understanding the real-life experience of the software. Any bugs found at this stage in being cleared out at the next software update.

5. What is the disadvantage of Functional testing?

Ans: The various disadvantages are as follows:

  • Testing only helps in identifying existing bugs but not their absence.
     
  • Logical errors can be missed, which can be dangerous for the expected performance.
     
  • It doesn't guarantee that the code will be bug-free when hosted live.

6. What are the different coverage criteria?

Ans: The different Coverage Criteria are as follows:

  • Path coverage: This makes sure that tests cover every possible path.  Cycles create infinite paths; hence it is not feasible for them. Acyclic graphs can still have an exponential number of paths.
     
  • State Coverage: Every node present is executed on minimum testing parameters.
     
  • Transition coverage: Every existing edge is executed thoroughly.

7. What are the recommendations for writing good test cases?

Ans: Write tests that cover specific features and achieve good code coverage. At different levels of functionality, tests should cover your system’s tests.Set up your tests in such a manner that when a failure occurs, it notifies the issue so that not much time gets wasted in debugging the issue.

8. What is Random Testing?

Ans: Random testing includes picking up inputs uniformly. All different inputs are treated equally. There should be no biases based on design because it may sometimes lead to error due to bad assumptions and some logical mistakes.

9. What are the different Functional Testing tools widely used?

Ans: The Functional Testing Tools widely used are as follows:

  • Selenium 
     
  • Ranorex Studio
     
  • TestComplete
     
  • Katalon studio

10. What is Defect Removal Efficiency?

Ans: It is the measure of how effectively the developers have solved the errors before launching the application. It is basically the ratio of the number of errors generated by the number of errors solved.

11.What do you understand by the term Defect Life Cycle?

Ans: This software Testing cycle begins with the finding of a bug and gets completed when the tester assures that this defect is being resolved completely. These different phases in which the bugs go from detection to getting completely resolved are called the Defect Life cycle.

Hard-Level Interview Questions

Here is a list of some advanced functional testing interview questions.

1. What is the difference between functional and non-functional testing?

Ans: The difference between functional testing and non-functional testing are as follows:

Functional Testing Non-Functional Testing
Testing is done on the basis of  ‘What’ the system should do. Testing is done on the basis of ‘How’ the system should work.
Tests the actions and working functionalities of the application by comparison of obtained output and desired output. Tests the non-functionality side of the application, mainly looks and feel of the user. E.g., Performance, Security, Usability.
Performed Before Non-Functional Tests. Performed after functionality tests – applicable in System Testing phase.
Focus lies on user/business requirements Focus lies on User Expectations/Experience

• Unit Testing 

• Integration Testing 

• System Testing 

• Acceptance Testing

• Performance Testing 

• Security Testing 

• Recovery Testing 

• Usability Testing

2. Explain different types of Functional Testing.

Ans: The different types of functional testing are as follows:

  • Unit Testing: Unit testing, in simple terms, validates if the separate units of code function properly as expected. For example, it validates if the piece of code is working as intended. It is written by developers. 
     
  • Integration Testing: Integration testing verifies the interfaces or the flow between the units. The focus is given to verifying the integrating links. 
     
  • Smoke Testing: Smoke testing is performed once after developers publish the ‘new build’, usually unstable – to evaluate critical functionalities of the system. The objective of the testing is to verify the most important functionalities of the system and not run an exhaustive testing process. Critical functionality test cases are chosen, run and verified. Both testers and developers perform smoke testing, and the testing is ‘build’ focused. 
     
  • Sanity Testing:  Focuses on executing test cases that are related to the changes made to the builds. In simple terms, when a build, usually stable, is received with minor changes, a sanity test is performed. It is performed by testers.

3. What are the steps carried out during Functional testing?

Ans: The steps carried out during functional testing are as follows:

  • Know the demand: Before conducting functional requirements, a proper study should be done to know the business demands.
     
  • Generating Test Cases: Test cases should be created in such a way that it meets all the business demands and keep in mind all the worst-case scenarios.
     
  • Run input data: With the input generated, run to check all the functions of the application and generate outputs.
     
  • Validate output results: With the output thus obtained, compare the result obtained vs. the results expected.
     
  • Spotting Weakness: With the comparison between the output obtained and the target output, it becomes clear for the testers to identify the weaknesses in the application and ask the developers to fix them to improve quality.

4. How should one prioritize the key factors when conducting Risk-based Testing?

Ans: Risk-based testing is a software testing approach in which the testing is based on the risk associated with each component of a software application. Prioritizing key factors in risk-based testing needs a systematic approach.

First, you should identify the potential risks associated with the software project, considering factors like complexity, important functionality, and dependencies. Then, assess each risk's impact and probability of occurrence. Then, you can prioritize high-impact, high-probability risks. You should also consider the business and project objectives. It is also important to regularly adjust the priorities as the development process advances.

5. What do you understand by Retesting and Regression?

Ans: Retesting: When an error is detected, Retesting refers to the process in which all the error that was detected earlier now gives correct result after fixing them. We cannot do retesting using automation. It is carried out once the errors are fixed.
Regression: It refers to the type of testing in which we check that the changes made in the code do not affect the system's performance and functionality. It does not point out the defect in the software. It can be done by automation easily because doing it is a tedious and a time taking procedure.

6. What are Defect Severity and Defect Priority?

Ans:  Defect Severity: It can be defined as the level of disturbance by the defect in the software at the testing phase. The higher is the impact, the higher the severity of the application. It can categorized under these four categories:

  • Critical
     
  • Major
     
  • Minor
     
  • Trivial
     

Defect Priority: It can be defined as the seriousness of the defect. More the Defect priority, the more the impact of the defect on the application. Defects with high priority should be addressed quickly. It can be broadly classified under three categories:

  • High
     
  • Medium
     
  • Low

Conclusion

In this article, we have discussed functional testing interview questions. Functional testing is very crucial for any software/application. Businesses that think Functional testing is not so necessary and skip this crucial stage, and are in a hurry to launch their products in the market will have to face bad reviews of their end users when the app doesn’t work as specified. Therefore, it is very important for teams to choose the right testing tools to get the most out of functional testing and help the business provide products that they promised error-free.

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