SDET Interview Questions

A SDET (Software Development Engineer in Test)is an IT professional with experience in both the development and testing environments. SDETs can assist in software development and testing at all levels. Currently, SDETs are in high demand across all industries. This blog focuses on the most often asked SDET interview questions across different areas. Take a look!

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An SDET is a specialist in the computer business who can write and evaluate code for automated testing programs. They create testing systems that allow them to evaluate code depending on various parameters. In other words, this profession is a hybrid of a software developer and QA engineer. 

Here are some SDET Interview Questions to help you learn more about the subject and advance your knowledge.

We have categorized SDET Interview Questions - 2024 (Updated) into 3 levels they are:

Frequently Asked SDET Interview Questions and Answers

  1. What is SDET?
  2. How can you test the text box without background functionality?
  3. What is Exploratory Testing?
  4. What do you understand about ad-hoc testing?
  5. What is a bug report in the context of software testing?
  6. What do you understand about severity and priority in the context of software testing?
  7. What do you understand about alpha testing? What are its objectives?
  8. Differentiate between Alpha testing and Beta testing.
  9. What do you understand about Risk-based testing?
  10. Differentiate between walkthrough and inspection

SDET Interview Questions For Freshers

1. What is SDET?

A Software Development Engineer in Test (SDET) is a term used to describe the testing on a software product. SDETs are involved in the entire software development and testing process. The knowledge of SDET professionals is solely focused on the testability, robustness, and performance of the software testing and development process. Their main goal is to create and deploy automated testing solutions to improve the end-user experience.

If you want to enrich your career and become a professional in Quality Assurance, then enroll in "Quality Assurance Training". This course will help you to achieve excellence in this domain.

2. Differentiate between Software Development Engineer in Test (SDET) and Manual Tester.

A tester is a person who conducts software testing to identify problems. In addition, the tester looks at several aspects of the software. The following table compares and contrasts an SDET and a Manual Tester:

Software Development Engineer in Test(SDET)Manual Tester
A tester who is also a coder is referred to as an SDET.After software or systems have been developed, a tester tests them.
Design, implementation, and testing are all areas where SDET excels.The software's design and implementation are unknown to the tester.
SDET also looks at how well the software works.The tester's sole responsibility is testing.
SDET is knowledgeable about software needs and associated topics.A tester's knowledge of software requirements is limited.
SDET is involved in the software development life cycle at every stage.Testers have fewer responsibilities and play a minor part in the software development life cycle.
SDETs must code because they may be asked to perform both automated and manual testing.Because manual testing is required of testers, they do not need to be coding experts.

3. How can you test the text box without background functionality?

This can be done without giving any data, for example.

  • Special Characters
  • Size of the Text Field
  • Alphanumeric Values
  • Minimum/Maximum Characters
  • Text Format

4. What are the principles of Software Testing?

Following are the principles of software testing:

  • Testing shows the presence of defects
  • Exhaustive testing is impossible
  • Early testing
  • Defect clustering
  • Pesticide Paradox
  • Testing is context depending
  • Absence of error fallacy
Check out : Types of Software Testing

5. What is Exploratory Testing?

Exploratory Testing is a test where a tester is unaware of the requirements and only does the test to investigate the application's functionality. Domain specialists usually conduct exploratory testing.

6. What is Fuzz Testing?

The practice of finding security flaws and coding problems and hackable software defects is known as fuzz testing. It is conducted by inserting a massive amount of random, erroneous, and unintentional data into the system to cause it to crash and then determining whether anything has broken into the system.

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7. Discuss Typical working day of SDET

You spend most of your time on the next chores daily:

  • Recognize the project's requirements.
  • Making and running test cases
  • Bug reporting and testing

You must also provide feedback to the design and development staff.

8. Name the different categories that test cases are grouped by.

The following are some of the most common types of test cases used in software development:

  • Functionality Test cases
  • User interface Test Cases
  • Performance Test Cases
  • Integration Test Cases
  • Usability Test Cases
  • Database Test Cases
  • Security Test Cases

9. What do you understand about ad-hoc testing?

Ad hoc testing is a type of unorganized or impromptu software testing that aims to disrupt the testing process as soon as possible in order to find any defects or errors. It is carried out at irregular intervals and is generally an unscheduled action that does not employ any paperwork or test design approaches to create test cases.

Ad-hoc testing is performed at random on any part of the application and does not adhere to any testing protocols. The main purpose of this testing is to find flaws by inspecting them at random. Ad hoc testing can be accomplished using Error Guessing, a software testing approach. Error guessing is a technique that allows people who are knowledgeable enough with the system to "predict" the most likely source of mistakes. No paperwork, planning, or procedure is required for this testing. Defects will not be mapped to test cases if there is no documentation because this testing uses a random technique to find problems. Because there are no test methods or requirements connected with faults, replicating them can be challenging at times.

10. What do you know about code inspection in the context of software testing? And, what are its advantages?

Code inspection is a type of static testing that entails looking over software code for problems. It reduces the defect multiplication ratio and eliminates future stage error detection by simplifying the initial error detection technique. This code review is part of the application review process.

The significant steps in code examination are as follows:

  • The Moderator, Reader, Recorder, and Author are the significant members of an Inspection team.
  • The inspection team receives relevant papers, plans the inspection meeting, and communicates with the other inspection team members.
  • The author provides an overview of the project and its code to the inspection team unfamiliar with it.
  • Each inspection team uses inspection checklists to conduct a code inspection.
  • After the code inspection is completed, hold a meeting with all team members to discuss the inspected code.

The following are some of the benefits of Code Inspection:

  • Code inspection improves the product's overall quality.
  • It detects software problems and weaknesses.
  • In any case, it signifies a process improvement.
  • It quickly and effectively detects and eliminates functional flaws.
  • It helps to repair previous flaws.

Scenario-Based SDET Interview Questions

11. What is a bug report in the context of software testing?

A bug report is a detailed document that explains what is wrong with the software or a website and how it should be fixed. A request and directions on how to remedy each issue are included in the report, as well as a list of causes or recognized faults to indicate precisely what is deemed to be wrong. 

Bug reports alert developers about parts of their code that aren't behaving as expected or designed, allowing them to determine which aspects of their product need improvement. This is a strenuous effort for the developer, and it is almost impossible without enough information. Fortunately, testers can help by writing high-quality bug reports that include all of the information a developer might need to track down the problem.

12. What are the elements of a bug report?

The elements of a bug report are as follows:

  • TITLE: A good title is brief, concise, and gives the developer a description of the bug. It should include the bug's classification, the app component where the bug occurred (e.g., Cart, UI, etc. ), and the action or conditions that caused the bug. A clear title helps the developer locate the report and identify duplicate reports, making problem triage much easier.
  • SEVERITY AND PRIORITY: The intensity of a problem is determined by how serious it is. The severity levels and definitions differ across programmers, and much more so among programmers, testers, and end-users who aren't aware of the differences. The following is the conventional categorization:
  • Critical/Blocker: This category is for bugs that make the application unusable or cause considerable data loss.
  • High: When a defect affects a key functionality and there is no workaround or the solution is exceedingly difficult to implement.
  • Medium: The fault impacts a minor or major feature, but it's easy enough to correct to avoid substantial inconvenience.
  • Low: This is for minor visual faults and other issues that have a slight influence on the user experience.
  • DESCRIPTION: This is a brief description of the bug, including how and when it appeared. If the defect is an intermittent error, this section should include more information than the title, such as the frequency with which it occurs and the situations that appear to trigger it. It includes details on how the bug is affecting the programme.
  • ENVIRONMENT: Depending on their circumstances, apps might act in a variety of ways. This section should include all of the details concerning the app's environment setup and configuration.
  • REPRO STEPS: This should just provide the absolute minimum of information required to reproduce the bug. The steps should preferably be short, simple, and easy to follow by everyone. The developer's goal is to be able to duplicate the problem on their end in order to figure out what's wrong. A defect report without repro steps is meaningless, wasting time and effort that could be better spent addressing more comprehensive reports; make sure to communicate this to your testers in a way that your end-users understand.
  • ACTUAL RESULT: As a result or output, this is what the tester or user observed.
  • EXPECTED RESULT: This is the result or outcome that is expected or planned.
  • ATTACHMENTS: Attachments can help the developer discover the problem faster; a screenshot of the problem, especially if it's a visual problem, can explain a lot. At the very least, logs and other extremely useful attachments can point the developer in the right direction.
  • CONTACT DETAILS: If you need any additional information about the problem, offer an email address where you may reach the user who reported the bug. It may be tough to get the user to respond to emails, therefore you should consider providing alternate communication channels that are less of a hassle for the user to improve efficiency.

13. What are the do’s and don'ts for a good bug report?

The following are some guidelines for writing a solid bug report:

  • Read your report once you've completed it. Ensure that it is clear, concise, and easy to comprehend.
  • Don't leave any room for ambiguity by being as specific as possible.
  • Test the problem a few times to see if any steps are unnecessary.
  • In your report, include any workarounds or extra procedures you've uncovered that cause the problem to behave differently.
  • Check to determine if the bug has been reported before. If it has, please post a comment with your details about the bug.
  • Respond to developer requests for additional information.

The following are some don'ts while writing a bug report:

  • DO NOT submit a report containing multiple bugs. It's tough to maintain track of the progress and dependencies of several problems in a report when there are a lot of them.
  • DO NOT pass judgment or accuse others. Bugs are unavoidable, but they're not always easy to eliminate.
  • DO NOT attempt to determine the source of the bug. To avoid putting the developer on a wild goose chase, stick to the facts.
  • Any information that isn't a bug should be shared. Developers value your feedback, but sending it to the wrong channel will stymie their workflow and cause delays.

14. What are the roles and responsibilities of a Software Development Engineer in Test (SDET)?

A Software Development Engineer in Test (SDET) has the following duties and responsibilities:

  • SDETs should be able to automate tests and create frameworks across several platforms, including web, mobile, and desktop.
  • Investigate customer concerns that technical support has referred to you.
  • Create, manage, and share bug reports with the rest of the team.
  • Create as many test cases and acceptance tests as you can.
  • SDET facilitates technical meetings with Partners in order to obtain a better grasp of the client's systems or APIs.
  • SDET also collaborates closely with deployment teams to address any issues at the system level.
  • Test automation frameworks must be created, maintained, and run by SDETs.

15. What do you understand about severity and priority in the context of software testing? Differentiate them.

  • Severity- When it comes to testing, severity relates to how much of an influence it has on the computer software being tested. A higher severity rating means the bug/defect has a bigger impact on the system's functionality. A Quality Assurance engineer usually determines the severity degree of a bug or defect.
  • Priority- Priority refers to the order in which a fault should be fixed. The higher the priority, the more quickly the issue should be resolved. Software flaws that make the system unusable are prioritised over flaws that merely affect a small fraction of the software's functioning.

The differences between priority and severity are listed in the table below:

Its value is subjective and may change over time depending on the circumstances of the project.It has a fixed value that is unlikely to change.

Priorities are grouped into three groups:

  • Low
  • Medium
  • High

There are five different degrees of 

  • Severity:
  • Critical
  • Major
  • Moderate
  • Minor
  • Cosmetic
Priority determines the order in which a developer should repair bugs.The influence of a problem on the product's operation determines its severity.
Priority has to do with when bugs are scheduled to be fixed.The severity of an application is determined by its functionality or standards.
The consumer's requirements define the priority status.The severity level is determined by the technical elements of the product.
The development team prioritizes and addresses issues during UAT (User Acceptance Testing).The development team will prioritize and resolve defects based on their severity during SIT (System Integration Testing).
The priority of a problem indicates how urgently it should be fixed.The severity of the defect's impact on the product's functionality is determined by its severity.
The priority of flaws is set in consultation with the manager/client.The QA engineer determines the defect's severity level.
When a problem has a high priority but a low severity, it suggests it needs to be fixed right away but isn't causing any problems with the programme. When an issue has a high severity but a low priority, it indicates that it should be fixed, but not right now.

16. What do you understand about alpha testing? What are its objectives?

Alpha testing is a sort of software testing that is intended to identify flaws in a product before it is distributed to real users or the wider public. Alpha testing is one sort of user acceptance test. Alpha testing is named for the fact that it takes place at the end of the software development process. Alpha testing is typically conducted by Homestead software engineers or quality assurance professionals. It's the final stage of testing before the programme is made available to the public.

The objectives of alpha testing are as follows:

  • Alpha testing is used to improve a software product by detecting flaws that were missed during previous tests.
  • Alpha testing is used to improve a software product by discovering and fixing flaws that were missed during previous tests.
  • The purpose of alpha testing is to involve clients as early as possible in the development process.
  • During the early stages of development, alpha testing is performed to acquire a better grasp of the software's reliability.

17. What do you understand about beta testing? What are the different types of beta testing?

Genuine consumers of the software product conduct beta testing in a real-world context. User Acceptance Testing, sometimes known as beta testing, is a type of UAT. A small number of product users are provided with a beta version of the application in order to provide input on the quality of the product. Beta testing reduces the danger of a product failing and improves its quality by allowing users to validate it.

Various types of beta testing are as follows:

  • Traditional Beta testing: Traditional Beta testing is delivering the product to the target market and gathering all pertinent data. This data can be utilised to help the product become better.
  • Public Beta Testing: The product is made available to the broader public through web channels, and anyone can contribute data. On the basis of user feedback, product enhancements might be implemented. Prior to the official release of Windows 8, Microsoft, for example, conducted the largest of all Beta Tests.
  • Technical Beta Testing: A product is provided to a group of firm employees, and the employees' feedback/data is collected.
  • Focused Beta Testing: A software product is made available to the general public in order to get feedback on certain programme features. The most significant aspects of the software, for example.
  • Post-release Beta Testing: Data is collected after a software product is released to the market in order to improve the product for future releases.

SDET Interview Questions For Experienced

18. Differentiate between Alpha testing and Beta testing.

Alpha testingBeta testing
In alpha testing, both white box and black box testing are used.In beta testing, black box testing is used.
Alpha testing is typically carried out by corporate workers who are also testers.Clients who are not corporate employees participate in beta testing.
On the developer's premises, alpha testing takes to occur.The product's end-users are used for beta testing.
There is no reliability or security testing in alpha testing.Reliability, security, and robustness are all tested during beta testing.
Alpha testing ensures that the product is of good quality before moving on to beta testing.Beta testing focuses on product quality, user feedback, and verifying that the product is ready for real-world use.
The usage of a lab or a testing environment is required for alpha testing.The utilization of a testing environment or laboratory is not required for beta testing.
It's possible that alpha testing will demand a lengthy execution cycle.Beta testing requires only a little amount of time.

19. Mention some of the software testing tools used in the industry and their key features.

The following are some of the most often used software testing tools in the industry:

TestRail - TestRail is a scalable and versatile web-based test case management system. You may set up our cloud-based/SaaS solution in minutes, or you can set up your own server on TestRail.

Testpad - Testpad is a simple and easy-to-use manual testing tool that promotes the practicality above approach. Rather than processing cases one at a time, it uses checklist-inspired test plans that may be changed in a variety of ways, including exploratory testing, Agile's manual side, syntax-highlighted BDD, and even classic test case management.

Xray - Xray is a feature-rich solution that is integrated into Jira and works seamlessly with it. Its goal is to help companies improve the quality of their products by conducting efficient and effective testing.

Practitest - PractiTest is a full-featured test management system. It serves as a single meeting platform for all QA stakeholders, providing comprehensive visibility into the testing process and a better, broader understanding of testing findings.

SpiraTest - SpiraTest is a cutting-edge Test Management solution that can be used by both large and small teams. Spiratest enables you to manage requirements, plans, tests, issues, tasks, and code all in one place, allowing you to completely embrace the agile methodology. SpiraTest is ready to use right now and adapts to your requirements, methodology, workflows, and toolchain.

TestMonitor - TestMonitor's end-to-end test management features can assist any company. It's a simple and uncomplicated testing procedure. Whether you're implementing corporate software, require QA, want to build a high-quality app, or just need a helping hand, TestMonitor can assist you with your test project.

20. What do you understand about performance testing and load testing? Differentiate between them.

  • Performance Testing: Performance testing is a type of software testing that ensures that software programmes work as intended in specific circumstances. It's a way of determining a system's sensitivity, reactivity, and stability when it's put to a given workload. Performance testing is the process of evaluating a product's quality and capacity. It's a method of measuring how well a system operates under varied loads in terms of speed, reliability, and stability. Performance testing is also known as perf testing.
  • Load Testing: Load testing is a sort of performance testing that evaluates the performance of a system, software product, or software application under realistic load conditions. Load testing determines how a programme performs when it is used by multiple people at the same time. It's a measure of a system's responsiveness under varied load conditions. Load testing is carried out under both normal and extreme load conditions.

The distinctions between Performance Testing and Load Testing are listed in the table below:

Performance TestingLoad Testing
Performance testing is the process of determining a system's performance, which includes speed and reliability under varying loads.Load testing is the process of determining how a system performs when multiple users access it at the same time.
In terms of performance, the load on which the system is tested is typical.The maximum load is utilised in load testing.
It looks at how well the system performs in normal circumstances.It looks at how the system performs while it's under a lot of stress.
In performance testing, the load limit is both below and over the break threshold.In load testing, the limit of load refers to the point at which a break occurs.
It examines the system's performance to ensure that it is satisfactory.It determines the operational capacity of a system or software application.
Speed, scalability, stability, and dependability are all investigated during performance testing.Only the system's long-term viability is tested during load testing.
Performance testing tools are less expensive.The cost of load testing equipment is high.

21. Explain some expert opinions on how a tester can determine whether a product is ready to be used in a live environment.

Because this is such a significant choice, it has never been made by a single person or by a group of junior guys. Senior management is regularly involved in this decision, which is not simply determined by the developer and tester. Management tests validate the following to guarantee that product delivery is bug-free:

  • Validating the bug reports given by the tester. What was done to resolve the bug, and did the tester retest it?
  • Validating the tester's test cases, as well as the documentation and confirmation received from the tester, for that specific capability.
  • Conduct automated tests to ensure that new features do not conflict with current ones.
  • Validating test coverage report, which verifies that all of the test cases for the developing component have been written.

22. What do you understand about Risk-based testing?

  • Risk-based testing (RBT) is a software testing strategy that is based on the possibility of a risk occurring. It comprises assessing the risk based on a variety of characteristics, including software complexity, business criticality, frequency of use, and potential Defect areas, among others. Risk-based testing prioritises the testing of software programme parts and functions that are more critical and more likely to have errors.
  • The occurrence of an unknown event that has a positive or negative impact on the project's assessed success criteria is referred to as risk. It could be something that occurred previously, is currently occurring, or will occur in the future. Unexpected events may have an impact on a project's cost, business, technical, and quality objectives.
  • Risks can be beneficial or harmful. Positive risks are referred regarded as opportunities, and they help a company's long-term existence. A few examples are investing in a new project, revamping company processes, and generating new products.
  • Negative risks are also known as threats, and reducing or eliminating them is essential for project success.

23. What is Equivalence Partitioning, and how does it work? Use an example to demonstrate your point.

Equivalence Partitioning and Equivalence Class Partitioning are the same things (ECP). It's a software testing method that divides the input domain into data classes from which test cases may be built. Another word for it is black-box testing. An ideal test case detects a type of flaw that may require the execution of a large number of arbitrary test cases before a general issue is detected. Equivalence partitioning determines whether there are several classes of equivalence for a given set of input conditions. The Equivalence class inspects the type of input condition and specifies or explains a set of valid and invalid states for this input condition when any input is presented.

Example 1 -  Let's look at an example of a normal college admissions process. Students are admitted to a college based on their grade point average. Consider a percentage field that only accepts percentages between 50 and 90%; anything higher or lower will cause the visitor to be redirected to an error page. The equivalence partitioning approach will display an invalid percentage if the user provides a percentage that is less than 50% or greater than 90%. If the percentage entered is between 50 and 90%, the equivalence partitioning technique will display a valid percentage.

Example 2 - As an example, consider the software application below. A function in a software application accepts only a specified amount of numbers, neither larger nor smaller than that number. Consider an OTP number with only six digits; anything longer or shorter than that will be refused, and the client or user will be directed to an error page. The equivalence partitioning technique will display an invalid OTP if the user's password is less than or equal to six characters. If the password is exactly six characters, the equivalence partitioning approach will display a valid OTP.

24. Would you forego thorough testing in order to release a product quickly?

These questions are designed to help the interviewer understand your leadership style, as well as what you would compromise on and whether you would be willing to produce a subpar product in exchange for less time.

The candidate's answers to these questions should be backed up with real-life experiences.

For example, you may explain that in the past you had to decide whether or not to issue a hotfix, but you couldn't test it since the integration environment was unavailable. So you started with a tiny percentage and monitored logs/events before initiating the full rollout, and so on.

25. What are the types of bugs detected by fuzz testing?

The following are the many stages of Fuzz Testing:

  • Identify the Target System: It is determined which system or software programme will be tested. The name assigned to that system is the target system. The target system is determined by the testing team.
  • Identify Inputs: Random inputs are created for testing reasons once the target system has been established. These random test scenarios are used as inputs to test the system or software application.
  • Generate Fuzzed Data: These faulty and unexpected inputs are transformed into fuzzed data after they are received. Random data that has been turned into fuzzy logic is referred to as fuzzy data.
  • Use fuzzed data to run the test: It is presently being used in the fuzzed data testing procedure. Basically, random input, i.e. fuzzed data, is used to execute the code of the programme or software in this section.
  • Monitor System Behavior: Check for any crashes or other irregularities, such as potential memory leaks, after the system or software programme has concluded its execution. The system's behaviour is tested using random input.
  • Log Flaws: Defects are found and corrected in the final phase to provide a higher-quality system or software programme.

The following are the various types of bugs that fuzz testing can detect:

  • Failures in assertions and memory leaks- This method is frequently used in large systems where memory safety is at risk, which is a severe problem. 
  • Invalid data -Fuzz testing uses fuzzers to generate defective input that is used to test error-handling procedures, which is crucial for software that has no control over its input. Negative testing can be automated using simple fuzzing.
  • Correctness bugs - Fuzzing can also be used to discover some types of "correctness" problems. For instance, a faulty database, insufficient search results, and so on.

26. What is the difference between Quality Assurance and Quality Control?

The main distinction between Quality Assurance and Quality Control is that the former focuses on the quality process, whilst the latter focuses on the output quality.

  • Quality Assurance is a preventive technique that emphasizes the importance of planning, documenting, and agreeing on a specific set of criteria for assuring quality. It is done at the start of a project with the goal of preventing flaws from entering the solution in the first place.
  • Quality Control is a proactive strategy that encompasses all efforts targeted at determining the quality of solutions given. It aids in the verification of output quality compliance with defined quality standards.
Check out : Quality Assurance vs Quality Control

27. What do you understand about a test script? Differentiate between test case and test script.

Test scripts are a chain explanation of the system transactions that must be executed to validate the software system being tested. The test script should include a list of each step as well as the intended outcomes. Software testers can extensively test each stage by running this automation script on a range of devices. In the test script, you must include both the real items to be completed and the expected results.

The differences between a test case and a test script are summarised in the table below:

28. Differentiate between walkthrough and inspection.

It's a laid-back atmosphere.It is formal in nature.
It is started by the developerIt is started by the project team.
Throughout the walkthrough, the product's developer takes the lead.A crew of people from various departments conducts the inspection. Members of the same project team frequently attend the tour.
A checklist is not used throughout the walkthrough.To find vulnerabilities, a checklist is employed.
The walkthrough process includes an overview, minimal preparation, minimal preparation evaluation (actual walkthrough meeting), rework, and follow-up.The inspection process includes the following steps: overview, preparation, inspection, rework, and follow-up.
There is no clear process for the steps.A protocol has been established for each phase.
The walkthrough takes less time because there is no set checklist to evaluate the programme.Because the checklist elements are checked off one by one, an inspection takes longer.
In most cases, it is unplanned.Meeting with pre-determined responsibilities for all attendees.
There is no moderator because it is unmoderated. The moderator's job is to keep the discussion on track.

29. What do you understand about white box testing and black box testing? Differentiate between them.

Black Box Testing: The most typical source of black-box testing is the customer's declaration of requirements. It's not the same as manual testing. It's a software testing method that focuses on the software's functioning rather than its internal structure or coding. It does not demand any prior understanding of software development. All test cases are written with a certain function's input and output in mind. The test engineer compares the programme to the specifications, finds any flaws or defects, and sends it back to the developers.

White Box Testing: The ability to see into the inner workings of software via its exterior shell is referred to as "clear box," "white box," or "transparent box" testing. Developers perform it, after which the software is given to the testing team for black-box testing. White-box testing's main purpose is to look into an application's infrastructure. Unit and integration testing are included, therefore it is done at a lower level. Because it primarily focuses on the code structure, routes, conditions, and branches of a programme or software, it requires programming expertise. White-box testing focuses on the software's inputs and outputs while also guaranteeing its security.

The following table compares and contrasts black box and white box testing:

30. Swap the values of two variables, x and y, without needing a third variable.

Approach 1:

The objective is to find the sum of one of the two numbers given. The integers can then be swapped using the total and subtraction from the sum.


#include <bits/stdc++.h>
using namespace std;

int main()
   int a = 1, b = 2;

   cout << "Before Swapping : a = " << a << " and b = " << b << "\n";
   a = a + b; // storing the sum of a and b in a
   b = a - b; // storing the value of the original a in b
   a = a - b; // storing the value of the original b in a
   cout << "After Swapping : a = " << a << " and b = " << b << "\n";


Before Swapping : a = 1 and b = 2
After Swapping : a = 2 and b = 1


The sum of both numbers was first saved in the first variable in the code above. Then, by subtracting the second variable from the sum, we save the original value of the first variable in the second variable. We alter the value of the second variable in the same way. As a result, we were able to swap the two numbers without the use of a third variable.

Approach 2 :

Using the bitwise XOR operator, you can swap two variables. When two numbers, x and y, are XORed, the output is a number with all bits set to 1, with x and y bits differing. The XOR of the numbers 10 (in Binary 1010) and 5 (in Binary 0101), as well as the XOR of the numbers 7 (0111) and 5 (in Binary 0101) is 1111. (in Binary 0101). (0101). (0010). XOR the result with the other integer to switch the values. If you xor 1111 with 0101, you'll get 1010.


#include <bits/stdc++.h>
using namespace std;

int main()
   int a = 1, b = 2;

   cout << "Before Swapping : a = " << a << " and b = " << b << "\n";
   a = a ^ b; // storing the xor of a and b in a
   b = a ^ b; // storing the value of the original a in b
   a = a ^ b; // storing the value of the original b in a
   cout << "After Swapping : a = " << a << " and b = " << b << "\n";


Before Swapping : a = 1 and b = 2
After Swapping : a = 2 and b = 1


The xor of both numbers was first saved in the first variable in the code above. Then, by XORing the second variable with the total, we store the first variable's original value in the second variable. We alter the value of the second variable in the same way. As a result, we were able to swap the two numbers without the use of a third variable.


We are at the end of this blog. We hope that you will have a good understanding of some of the most important topics that are frequently asked in SDET Interview Questions.

If you have any queries or if you have any idea of adding some more questions to the above section, feel free to give your suggestion in the comment section below. We will get back to you with a clear answer to the suggested questions as soon as possible. Best of luck!

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Last updated: 03 Jan 2024
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Madhuri is a Senior Content Creator at MindMajix. She has written about a range of different topics on various technologies, which include, Splunk, Tensorflow, Selenium, and CEH. She spends most of her time researching on technology, and startups. Connect with her via LinkedIn and Twitter .

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