How to ace a QA interview
Embarking on a journey toward a career in software testing is an exciting and rewarding endeavor. As a software tester, the gateway to your dream job often involves navigating the challenging terrain of a Quality Assurance (QA) interview. Whether you’re a seasoned professional looking to make a career move or a budding enthusiast eager to step into the software testing world, mastering the art of answering QA interview questions is essential.
This comprehensive guide delves into the intricate landscape of QA interview questions, offering valuable insights, tips, and strategies to help you survive and thrive in your software testing interviews. From fundamental concepts to advanced methodologies, we’ll explore various topics encompassing the core competencies sought by interviewers in the dynamic field of software testing.
Let’s begin!
What is black-box testing?
Black box testing involves testing a software system in which we know only the input but do not see how the output gets produced.
What is functional testing?
Functional testing is one type of black-box testing. It consists of testing functions by feeding them input and evaluating the output. However, the inner workings of a program are rarely considered.
What is regression testing?
There are two ways to use regression testing, and the idea of reusing old tests is familiar to both.
- To ensure that a fix does what it’s supposed to do.
- To ensure that a fix does not compromise the overall integrity of a program.
What is acceptance testing?
Acceptance testing, or otherwise User Acceptance Testing (UAT), is the testing performed by end-users or stakeholders of a piece of software. It mainly tends to focus on validation-type testing.
What is the difference between validation and verification?
The IEEE Standard Glossary of Software Engineering Terminology (Std 610.12-1990) defines validation as below.
“The process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements.”
On the other hand, the same standard defines verification as follows.
- (1) The process of evaluating a system or component to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase.
- Formal proof of program correctness.
What is load testing?
Load testing is a performance testing technique that sees a system’s behavior under heavy demand. Load testing examples include but are not limited to the following.
- Test the system with the maximum number of users allowed.
- Send the maximum number of requests a system can handle at any time.
- Send the largest file size that a system can handle.
- Test a system under low memory conditions.
What is stress testing?
Stress testing is a performance testing technique used to test a system close to and beyond its “breaking point.” The intention is to test the system’s robustness. Below are some things we can measure by conducting a stress test.
- How well the system performs under extreme load.
- How well the system’s error handling capabilities perform under stress.
- What is the maximum number of users the system can handle before failing?
- How well the system performs when taking the maximum number of requests per second.
What are equivalence classes?
When we expect the same result from two tests, we say they are equivalent. A group of tests forms an equivalence class if they meet the following criteria.
- They all test the same thing.
- If one test catches a bug, the others probably will, too.
- If one test doesn’t catch a bug, the others probably won’t as well.
Source: Kaner, Falk, Nguyen. Testing Computer Software, pp. 128.
What is equivalence partitioning?
Equivalence partitioning is a systematic software testing technique in which the input domain of a system is divided into groups or partitions of equivalent conditions. The objective is to simplify test case selection by identifying representative values from each partition, as inputs within the same partition are expected to produce similar software behaviors.
Moreover, focusing on testing only one representative from each equivalence class makes the testing process more efficient, covering a wide range of scenarios while avoiding unnecessary redundancy.
What are state transitions?
State transitions refer to the different states that an application can be in. Take, for instance, an e-commerce website. When a user clicks Checkout, they see a payment screen; once they enter their payment info and click Purchase, it results in an empty shopping cart, followed by a confirmation screen.
Here are some of the things that we could test in this scenario.
- Does the program switch correctly from state to state?
- Is it possible to make the application do these things out of sequence?
- Is it possible to make the application lose track of its current state?
- What does the program do with user input while switching between states?
- Does the user get charged more than once if we click Purchase multiple times?
- Does the program crash if we refresh the application while processing a transaction?
What is a race condition?
A race condition can occur between two events. For the sake of argument, let’s call these events X and Y. If X comes first, the program works. Since the program always expects X to go first, it fails whenever Y comes first.
Race conditions can be challenging to troubleshoot because they only occur under particular conditions. Therefore, be vigilant for race conditions whenever you have “irreproducible” bugs!
What are boundary conditions?
Let’s assume we have a program with an input field where users can enter the current month in number format (e.g., January = 1 and December = 12). That would mean that the numbers between 1 and 12 (inclusive) would be acceptable values, while anything outside this range would be unacceptable or outside the boundaries. One boundary case would be 0 and 1; another possibility would be 12 and 13.
Not every boundary in a program is intentional, and not all intended boundaries are set correctly. This is what most bugs are–most bugs cause a program to change its behavior when the programmer didn’t want or expect it to, or cause the program not to change its behavior when the programmer did expect it to. Not surprisingly, some of the best places to find errors are near boundaries the programmer did intend.
Kaner, Falk, Nguyen, Testing Computer Software, pp. 5
What is beta testing?
We use beta testing to get user feedback. The main idea is to let people representing your market use your unfinished product as if it were the finished version. Their feedback solves most remaining bugs and any necessary changes before delivering the product to the market.
What is performance testing?
Performance testing is a type of non-functional testing. We use it to evaluate an application’s performance in varying circumstances. Moreover, it helps identify areas that need improvement before launching to the market.
Performance testing includes but is not limited to the following.
- Load testing
- Stress testing
- Soak testing
What is white box testing?
White box testing involves testing a software system in which we know the input and output and how the output gets produced.
What is risk-based testing?
Risk-based testing is a strategic approach to software testing that prioritizes testing activities based on the perceived risks associated with different components or functionalities of the system. This method involves identifying, assessing, and prioritizing potential risks, considering factors such as the probability of occurrence and the potential impact on the project.
Test efforts are then directed towards areas with higher perceived risks, allowing for more efficient resource allocation and increased focus on critical aspects of the software. By aligning testing efforts with project risks, risk-based testing aims to uncover and address the most significant threats to the software’s quality, ensuring that testing activities contribute most effectively to the project’s overall success.
What is exploratory testing?
Exploratory testing is a software testing method in which testers explore or understand the flow of the application in all possible ways due to the unavailability of requirements or predefined test cases. It mainly involves understanding the application first and trying different scenarios. After that, testers design and execute new test cases without predefined or prewritten test cases or scripts.
After the first round of exploring the application, testers have to identify potential scenarios with the help of their own creativity and prepare a document based on those scenarios. Testers then test the application by referring to that document and start testing the application’s functionalities without the help of predefined scripts or test cases. It is the very opposite of a classic testing method, which follows a detailed plan for the testing. Exploratory testing improves testers’ creativity and ability to navigate the entire application like a regular user.
These are the popular types of exploratory testing:
- Freestyle exploratory testing
- Scenario-based exploratory testing
- Strategy-based exploratory testing
What is smoke testing?
Smoke testing, often called build verification testing, acts as a preliminary check to ensure that the essential functionalities of a software build or update are working correctly. It involves running a basic set of test cases covering primary features to check the build’s stability quickly.
Imagine smoke testing as taking a quick look to make sure the software starts up without big problems. If everything seems okay, it means the software is ready for deeper testing. But if we find serious issues during this quick check, it tells us there might be bigger problems we must fix first. So, smoke testing helps catch major issues early on, ensuring the software is stable enough for more detailed testing later on.
What is test automation?
Test automation is all about using special tools to run tests independently without needing someone to do them manually. This makes testing faster, more reliable, and covers more ground. It’s super helpful for testing tasks that must be done repeatedly, like checking if new software changes break anything already working. Overall, test automation makes testing easier, quicker, and more thorough.
Here are some popular test automation tools:
What is a test case?
A test case is like a step-by-step guide that tells testers exactly what steps to follow to test a specific software part. It includes elements like what to input, what to expect as output, and any conditions needed for the test. Test cases are important because they ensure testing is done consistently and thoroughly, helping find any issues or problems in the software. They also serve as a record of what testing was done, which can be helpful for future testing or fixing any issues found.
A well-written test case consists of elements like:
- Test case ID
- Test case description
- Pre-conditions
- Test steps
- Test data
- Expected result
- Actual result
What is defect tracking?
Defect tracking is the process of identifying, documenting, prioritizing, and resolving defects found during testing. Defect-tracking tools are used to manage defects from detection to resolution. The main objective of defect tracking is to enhance the software development process by identifying and resolving issues promptly.
What is code coverage?
Code coverage is a software development metric that measures the percentage of code executed by tests during testing. It helps assess the effectiveness of testing efforts by indicating how much of the codebase has been executed by the tests.
This metric is calculated based on the lines, branches, or statements within the code that have been executed during testing. A higher code coverage percentage suggests that more parts of the code have been tested, while a lower percentage may indicate areas that require additional testing to ensure comprehensive test coverage.
It’s important to note that while code coverage is a valuable metric, achieving 100% coverage does not guarantee us a bug-free application. Other factors, such as the quality of test cases, edge cases, and the complexity of the code, can also impact testing effectiveness and the possibility of finding defects.
What is static testing?
Static testing is a software testing technique that aims to identify software defects without executing the application code. It is carried out in the early stages of development to identify and rectify defects. This is because it is easier to detect and fix the defects at this stage before the software becomes more complex. Static testing can find errors that may not be found through dynamic testing, making it an essential part of the testing process.
What is dynamic testing?
Dynamic testing is a type of software testing process that involves testing the dynamic behavior of the software code. This testing method requires compiling and executing the software, during which parameters like memory usage, CPU usage, response time, and overall performance are analyzed.
Additionally, dynamic testing involves testing the software with input values and analyzing the corresponding output values. Lastly, it involves working with the software by providing input values and checking if the output is as expected by executing respective test cases, which can be done either manually or with an automated process.
Different levels of dynamic testing techniques are used for software testing. The commonly known levels of dynamic testing techniques are:
- Unit testing
- Integration testing
- System testing
- Acceptance testing
What is API testing?
API testing involves verifying the functionality, reliability, and performance of Application Programming Interfaces (APIs). It ensures that APIs, which serve as the communication channels between different software systems, work as expected, providing accurate responses to requests and handling errors effectively.
Through API testing, developers and testers can validate various aspects of APIs, such as endpoints, request parameters, response formats, and authentication mechanisms, ensuring they meet the requirements of the applications they support.
API testing can only be done with the help of API testing tools. These are some of the popular API testing tools that are available in the market:
What is test-driven development (TDD)?
Test-driven development (TDD) is a methodology in software development where test cases are prepared before writing actual code. This unique approach requires creating failing tests based on the expected functionality or requirements of the software. Developers then write the code that fulfills these test cases, aiming to make them pass.
This process sticks to the Red-Green-Refactor cycle, where failing tests are prepared to specify the desired behavior in the Red phase. After that, in the Green phase, developers implement the minimum code necessary to pass these tests. Finally, during the Refactor phase, developers refine and optimize the code while ensuring all tests continue to pass seamlessly.
Adopting TDD offers numerous advantages, including enhanced code quality, minimized bugs, and improved design. By preparing test cases initially, developers gain a clearer understanding of the software requirements and its architectural design. Moreover, the complete test suite is a safety net, reassuring developers to refactor or modify code confidently, knowing it won’t break existing functionality.
What is continuous integration (CI)?
Continuous Integration (CI) is a software development practice where developers frequently integrate their code changes into a shared repository, typically multiple times daily. Each integration triggers automated build processes that compile the code, run tests, and generate feedback on the quality of the changes.
CI aims to detect integration errors early in the development cycle, ensuring that defects are identified and addressed promptly. By continuously integrating code changes, teams can detect issues quickly, maintain codebase stability, and improve overall software quality.
Several tools simplify the effective implementation of continuous integration practices. One of the most widely used CI/CD tools, Jenkins offers strong automation capabilities and extensive plugin support. It allows developers to automate the entire build and deployment process, including compiling code, running tests, and deploying applications to various environments.
With Jenkins, teams can configure flexible pipelines to automate repetitive tasks, streamline collaboration, and accelerate the software delivery pipeline. Other significant CI tools include GitLab CI/CD, Travis CI, CircleCI, TeamCity, and Bamboo, each offering unique features and integrations to streamline the CI workflow and improve development efficiency.
What is ad-hoc testing?
Ad-hoc testing is an informal software testing approach where testers explore the software without predefined test cases or structured test plans. Testers rely on their domain knowledge, experience, and instinct to find defects and issues spontaneously. Ad-hoc testing is typically unscripted and aims to identify defects quickly, especially in areas that formal test cases may not cover.
For example, suppose a tester is conducting ad-hoc testing on a web application’s registration form. Instead of following a predefined test script, the tester may interact with the form by entering various data combinations, intentionally deviating from expected inputs. They might input special characters, excessively long or short strings, or invalid formats to see how the form responds. Through this exploratory approach, the tester may uncover unexpected behaviors such as input validation errors, field truncation issues, or usability issues with error messages.
What are the advantages of agile software testing?
These are the advantages of agile software testing:
Continuous integration: Integrate code changes frequently to ensure compatibility and identify integration issues early.
Automated testing: Implement automated tests to speed up testing cycles and ensure consistent test coverage.
Test-driven development (TDD): Write test cases before code to describe requirements and ensure code meets specifications.
Parallel testing: Execute tests concurrently to reduce testing time and improve efficiency.
Incremental development: Deliver software in small, manageable units to facilitate testing and validation.
Cross-functional teams: Include testers in cross-functional teams to promote collaboration and shared responsibility.
Regression testing suites: Maintain comprehensive regression test suites to verify that new changes do not break existing functionality.
Continuous deployment: Automate deployment processes to quickly deliver new features and updates to customers.
What’s the difference between a bug and a defect?
A bug refers to a problem or flaw in a software application that results in unexpected behavior or incorrect output. Bugs are generally linked to software development and are specific to coding errors or mistakes made during software programming. They are often introduced during the coding phase due to logical errors, syntax mistakes, or the wrong implementation of requirements.
On the other hand, defect is a more general term that includes any deviation from a product’s expected behavior or functionality, which can also occur in software. Defects can arise at different stages of product development, including design flaws, documentation errors, hardware malfunctions, or even manufacturing issues.
What is test closure?
Test closure is a document that summarizes all tests performed during the software development life cycle, along with a complete analysis of the defects fixed and errors found. This record includes information on the total number of tests conducted, the total number of test cases executed, the total number of defects detected, the total number of defects resolved, the total number of unresolved bugs, and the total number of rejected bugs, among other things.
What is the defect life cycle?
A defect life cycle is a procedure by which a defect progresses through multiple stages throughout its existence. The cycle begins when a defect is discovered and ends when the defect is closed after it has been confirmed that it will not be reopened.
These are the following stages of the defect life cycle:
- Identification: Defect is found
- Logging: Defect details are recorded
- Assignment: Defect is assigned to a team member
- Prioritization: Defect severity is assessed
- Investigation: Root cause is determined
- Fixing: Developer resolves the defect
- Verification: Fix is tested
- Closure: Defect is marked as closed
- Reopening: If necessary, defect may be reopened
- Documentation and Analysis: Defect history is documented and analyzed for process improvement
When should you choose manual testing instead of automated testing?
Manual testing is preferable over automated testing in situations where the software features are frequently changing or when the initial investment in automation tools and scripts outweighs the benefits. Additionally, manual testing is more suitable for exploratory, ad-hoc, and user interface (UI) testing, where human instinct and observation are helpful. It is also preferred when testing small or one-time projects or when the test cases are complex to automate due to their complexity or variability. Ultimately, manual testing offers flexibility, adaptability, and human judgment, making it a practical choice for specific testing scenarios.
What is the difference between black, white, and gray-box testing?
Features | Black-box Testing | White-box Testing | Gray-box Testing |
---|---|---|---|
Internal code knowledge | Knowledge of internal code structure is not required | Knowledge of internal code structure is highly required | Knowledge of the internal code structure is partially required |
Skills required | Minimal programming knowledge required | In-depth programming knowledge needed | Moderate programming knowledge needed |
Test design | Based on specifications/requirements | Based on code structure and logic | Based on specifications and internal logic |
Implementation | Doesn’t require access to the source code and can be performed by testers, developers, or the end user. | Requires access to the source code and is only performed by developers and testers with programming expertise | Requires partial access to the source code and may involve collaboration between testers and developers. |
Examples | Functional Testing, System Testing | Unit Testing, Integration Testing | API Testing, Compatibility Testing, Database Testing |
What is the definition of the traceability matrix in software testing?
The traceability matrix in software testing is a document used to establish and track the relationships between different elements in the software development process, such as requirements, test cases, and defects. It provides a systematic way to ensure that each requirement has associated test cases for validation and that defects found during testing can be traced back to the specific requirements they affect. This helps ensure complete test coverage, identify gaps or missing requirements, and create effective communication between stakeholders involved in the project.
What is cross-browser testing?
A web application can be accessed through different browsers, such as Chrome, Mozilla Firefox, Microsoft Edge, Safari, and others. Although such browsers implement similar web standards, it’s crucial to perform cross-browser testing to verify whether your website or app functions properly across different browser-OS combinations.
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