Top Software Testing Interview Questions and Answers

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Software testing involves evaluating and verifying a software product’s functionality. Basically, it checks whether the software product matches anticipated requirements and makes sure it is defect-free. It can be said that testing enhances the quality of the product by preventing bugs, reducing development costs, and reducing performance issues.

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Different kinds of software testing are as follow:

• Unit Testing: A programmatic test that tests the internal working of a unit of code, such as a method or a function.
• Integration Testing: Ensures that multiple components of systems work as expected when they are combined to produce a result.
• Regression Testing: Ensures that existing features/functionality that used to work are not broken due to new code changes.
• System Testing: Complete end-to-end testing is done on the complete software to make sure the whole system works as expected.
• Smoke Testing: A quick test performed to ensure that the software works at the most basic level and doesn’t crash when it’s started. Its name originates from the hardware testing where you just plug the device and see if smoke comes out.
• Performance Testing: Ensures that the software performs according to the user’s expectations by checking the response time and throughput under specific load and environment.
• User-Acceptance Testing: Ensures the software meets the requirements of the clients or users. This is typically the last step before the software is live, i.e. it goes to production.
• Stress Testing: Ensures that the performance of the software doesn’t degrade when the load increases. In stress testing, the tester subjects the software under heavy loads, such as a high number of requests or stringent memory conditions to verify if it works well.
• Usability Testing: Measures how usable the software is. This is typically performed with a sample set of end-users, who use the software and provide feedback on how easy or complicated it is to use the software.
• Security Testing: Now more important than ever. Security testing tries to break a software’s security checks, to gain access to confidential data. Security testing is crucial for web-based applications or any applications that involve money.

Answer:

Software testing is directed by seven principles:

•  Absence of errors fallacy: Even if the software is 99% bug-free, it is unusable if it does not conform to the user’s requirements. Software needs to be bug-free 99% of the time, and it must also meet all customer requirements.
• Testing shows the presence of errors: Testing can verify the presence of defects in software, but it cannot guarantee that the software is defect-free. Testing can minimize the number of defects, but it can’t remove them all.
• Exhaustive testing is not possible: The software cannot be tested exhaustively, which means all possible test cases cannot be covered. Testing can only be done with a select few test cases, and it’s assumed that the software will produce the right output in all cases. Taking the software through every test case will cost more, take more effort, etc., which makes it impractical.
• Defect clustering: The majority of defects are typically found in a small number of modules in a project. According to the Pareto Principle, 80% of software defects arise from 20% of modules.
• Pesticide Paradox: It is impossible to find new bugs by re-running the same test cases over and over again. Thus, updating or adding new test cases is necessary in order to find new bugs.
• Early testing: Early testing is crucial to finding the defect in the software. In the early stages of SDLC, defects will be detected more easily and at a lower cost. Software testing should start at the initial phase of software development, which is the requirement analysis phase.
• Testing is context-dependent: The testing approach varies depending on the software development context. Software needs to be tested differently depending on its type. For instance, an ed-tech site is tested differently than an Android app.

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End to End testing is the process of testing a software system from start to finish. The tester tests the software just like an end-user would. For example, to test a desktop software, the tester would install the software as the user would, open it, use the application as intended, and verify the behavior.

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When software is being tested, the code coverage measures how much of the program’s source code is covered by the test plan. Code coverage testing runs in parallel with actual product testing. Using the code coverage tool, you can monitor the execution of statements in your source code. A complete report of the pending statements, along with the coverage percentage, is provided at the end of the final testing.

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Following are the different types of test coverage techniques:

• Statement/Block Coverage: Measures how many statements in the source code have been successfully executed and tested.
• Decision/Branch Coverage: This metric measures how many decision control structures were successfully executed and tested.
• Path Coverage: This ensures that the tests are conducted on every possible route through a section of the code.
• Function coverage: It measures how many functions in the source code have been executed and tested at least once.

Answer:

• Black-box testing in software testing: In black-box testing, the system is tested only in terms of its external behaviour; it does not consider how the software functions on the inside. This is the only limitation of the black-box test. It is used in Acceptance Testing and System Testing.
• White-box testing in software testing: A white-box test is a method of testing a program that takes into account its internal workings as part of its review. It is used in integration testing and unit testing.
• Grey-box testing in software testing: A Grey Box Testing technique can be characterized as a combination of a black box as well as a white box testing technique used in the software testing process. Using this technique, you can test a software product or application with a partial understanding of its internal structure.

Answer:

• Test Case: Test Cases are a series of actions executed during software development to verify a particular feature or function. A test case consists of test steps, test data, preconditions, and post conditions designed to verify a specific requirement.
• Test Scenario: Usually, a test scenario consists of a set of test cases covering the end-to-end functionality of a software application. A test scenario provides a high-level overview of what needs to be tested.
• Test Scripts: When it comes to software testing, a test script refers to the set of instructions that will be followed in order to verify that the system under test performs as expected. The document outlines each step to be taken and the expected results.

Answer:

Bugs and errors differ in the following ways:

• Software bugs are defects, which occur when the software or an application does not work as intended. A bug occurs when there is a coding error, which causes the program to malfunction. While, Errors in code are caused by problems with the code, which means that the developer could have misunderstood the requirement or the requirement was not defined correctly, leading to a mistake.
• The bug is submitted by the testers. Whereas, Errors are raised by test engineers and developers.
• Logic bugs, resource bugs, and algorithmic bugs are types of bugs. On the other hand, Syntactic error, error handling error, error handling error, user interface error, flow control error, calculation error, and testing error are types of errors.
• The software is detected before it is deployed in production. In contrast, the error occurs when the code is unable to be compiled.

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The risk-based testing is a testing strategy that is based on prioritizing tests by risks. It is based on a detailed risk analysis approach which categorizes the risks by their priority. Highest priority risks are resolved first.

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We might have developed the software in one platform, and the chances are there that users might use it in the different platforms. Hence, it could be possible that they may encounter some bugs and stop using the application, and the business might get affected. Therefore, we will perform one round of Compatibility testing.

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• The test driver is a section of code that calls a software component under test. It is useful in testing that follows the bottom-up approach.
• The test stub is a dummy program that integrates with an application to complete its functionality. It is relevant for testing that uses the top-down approach.

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• Bug leakage: Bug leakage is something, when the bug is discovered by the end user/customer and missed by the testing team to detect while testing the software. It is a defect that exists in the application and not detected by the tester, which is eventually found by the customer/end user.
• Bug release: A bug release is when a particular version of the software is released with a set of known bug(s). These bugs are usually of low severity/priority. It is done when a software company can afford the existence of bugs in the released software but not the time/cost for fixing it in that particular version.

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Verification evaluates the software at the development phase, ascertaining whether or not a product meets the expected requirements. On the other hand, validation evaluates the software after the development phase, making it sure it meets the requirements of the customer.

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This defect is an existing defect in the system which does not cause any failure as the exact set of conditions has never been met.

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Phantom is a freeware and is used for windows GUI automation scripting language. It allows us to take control of windows and functions automatically. It can simulate any combination of keystrokes and mouse clicks as well as menus, lists and more.

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When the presence of one defect hides the presence of another defect in the system, it is known as fault masking.

Example: If the “Negative Value” cause a firing of unhandled system exception, the developer will prevent the negative values input. This will resolve the issue and hide the defect of unhandled exception firing.

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The variation of regression testing is represented as N+1. In this technique, the testing is performed in multiple cycles in which errors found in test cycle ‘N’ are resolved and re-tested in test cycle N+1. The cycle is repeated unless there are no errors found.

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Fuzz testing is used to detect security loopholes and coding errors in software. In this technique, random data is added to the system in an attempt to crash the system. If vulnerability persists, a tool called fuzz tester is used to determine potential causes. This technique is more useful for bigger projects but only detects a major fault.

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Random testing is often known as monkey testing. In such type of testing data is generated randomly often using a tool or automated mechanism. With this randomly generated input, the system is tested, and results are analyzed accordingly. These testing are less reliable; hence it is normally used by the beginners and to see whether the system will hold up under adverse effects.