7 Basic Principles of Software Testing

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7 Basic Principles of Software Testing

Sameeksha Medewar
Last updated on April 14, 2024

    We use a variety of software today to perform different activities. For example, Google Maps, one of the widely used software applications, has made it easy to find and reach any location. With just a few clicks on our devices, we can accomplish complex tasks. In general, end-users expect a particular software product to be free from glitches or defects, provide a great user experience, and meet all their requirements. This is where software testing comes into play. Software testing is an integral part of the software development life cycle (SDLC). It provides insights into the gaps or missing requirements, defects, or errors in the software product. Also, it assures that the product developed meets the quality standards and the specified requirements. There are some principles or guidelines that testers or quality assurance (QA) professionals need to follow while performing testing. These principles help them utilize their time and effort and carry out software testing efficiently. This article will familiarize you with seven basic software testing principles that make the test process more effective and ensure high-quality software development. Also, we shall briefly discuss what software testing is and its importance.

    What is Software Testing?

    Software testing is a process to verify whether a particular software product complies with the specified requirements or behaves as expected without any flaws. The primary objective of software testing is to detect errors or defects and gaps or missing requirements in the software product concerning actual requirements. In short, software testing validates and verifies the software product for its correctness, functionality, reliability, and security. An adequately tested software product is reliable, free from defects, secure, and cost-effective. The success of any software product depends on its acceptance by end-users. Therefore, if a software product meets the requirements specified by end-users, it is more likely to become successful. Software testing helps in ensuring that the software product complies with the specified requirements. There are two ways to carry out software testing: manual and automated. Manual testing implies testing the functionality of software products without any tools. On the other hand, automation testing means testing software products using specific tools.

    7 Basic Principles of Software Testing

    Software testing principles help get optimum results while testing software without diverting from the intended goals. Every tester or quality assurance (QA) professional should know the seven fundamental software testing principles. These principles reduce their efforts and make the testing process more effective. Let us discuss the seven fundamental principles of software testing below.

    1. Testing Highlights the Presence of Defects

    The first principle states, "Testing talks about the presence of defects and not the absence of defects." Software testing identifies bugs and gets them fixed before making the software product live. However, it does not ensure that the software product is entirely free from defects. Though software testing reduces the number of defects present in the software product, it does not assure the absence of defects. Even multiple testing cannot guarantee a defect-free software product. After making the software product live to end-users, there may be a situation where users may encounter an unexpected defect or glitch in the software. Therefore, testing only highlights the presence of defects and not their absence. In a nutshell, this principle states that testing reduces the number of defects or bugs in the software product but does not remove all the defects.

    2. Exhaustive Testing is Not Possible

    Exhaustive testing is a kind of testing that tests and verifies the functionality of a software product using all valid and invalid inputs and pre-conditions. Even if you try very hard, it is impossible to test everything or cover every possible test case. Testing can cover only some major test cases and assume that the software product will work well and produce correct output for every test case. Moreover, testing every test case consumes a lot of time, which, in turn, increases the cost and effort. Therefore, exhaustive testing is not possible or is impractical. For example, consider that we need to test a text field that accepts alphabets, memorable characters, and numbers from 0 to 10,000. Many combinations would appear for testing, which would not be possible to test practically.

    3. Early Testing

    As its name suggests, early testing states that testing should start in the early stages of the software development life cycle, i.e., right in the requirements analysis phase. Early testing results in the identification of defects in the early stages. If we find defects early, we can fix them at less cost. To understand the importance of early testing, let us consider two scenarios. The first scenario is when you found the incorrect requirement in the requirements gathering and analysis phase. And the second one is when you find a defect in a fully functional or one of the software builds. The requirements gathering and analysis phase is the software development life cycle (SDLC). If you find any incorrect requirement, you can immediately correct it with the help of stakeholders or end-users. On the other hand, if you find any defect or bug in a fully-functional software, firstly, the development team needs to work on code to fix that particular defect and send it to the testing team. The testing team checks whether the bug is fixed or not. If not, the same process of repeated until the bug gets fixed. You can conclude the above two scenarios that the cost required for fixing the defect in the second scenario is higher than the cost required for fixing the defect found in the first scenario. Also, fixing the defect in the second scenario requires a lot of time and effort. Therefore, it is essential to introduce software testing in the early phases of SDLC.

    4. Defect Clustering

    Defect clustering means a small module or feature of the software product that contains more defects or operation issues. We know that each module or feature of the software product is different and less or more complicated. Therefore, defects or bugs are not evenly distributed, which leads to defect clustering. The Pareto principle (80-20 Rule) states that 80% of defects originate from 20% of the software modules, and the remaining 20% of defects originate from 80% of the software modules. Therefore, it is essential to prioritize testing on 20% of software modules that produce 80% defects. For the defect clustering method, the team's knowledge and experience are vital in choosing the software module for testing. If the team has the testing experience, it becomes possible to detect risky modules quickly.

    5. Pesticide Paradox

    Pesticide Paradox refers to repeating the same test cases for a particular period. When we repeat executing the same test cases for a specific period, we cannot detect new bugs in the software product. The principle of pesticide paradox is based on the theory that if we spray the same pesticide repeatedly on the crops to get rid of insects, it eventually boosts the insects' immunity, making the pesticide ineffective. Therefore, to eliminate the issue of pesticide paradoxes, it becomes necessary to review all the test cases regularly to detect new bugs in the software product. Also, testers need to constantly look for new ways to improve the existing test cases and develop new test cases for new software product features.

    6. Testing is Context-Dependent

    Testing for each type of software product is different, i.e., the testing process varies depending upon the type of software system. We can't follow the same design process for all software systems. This is because each product has a different set of requirements. As per this principle, testing depends on the context of the software product, which is true. For example, e-commerce or advertising websites require a different testing approach than online banking applications. Similarly, healthcare applications require more intense testing than gaming applications. Various testing methodologies, techniques, and types are available. The testing team has to choose the appropriate testing type, technique, and methodologies, depending upon the nature of an application.

    7. Absence of Error - Fallacy

    Once software testing completes and there are no bugs identified in the software system before its release, we can ensure that it is 99% bug-free. For the software application to be successful, it should be bug-free and meet all the requirements. If your software product does not meet the end user's or business's requirements, it remains unused. Therefore, even if your system is bug-free but does not match business requirements or lacks usability, it remains unused. So, testing should also ensure that the software product has met all the requirements specified by the stakeholders or end-users.


    Here we reach the end of the seven fundamental principles of software testing. We have discussed each principle of software testing in detail. All these principles help quality assurance (QA) professionals to develop and deliver high-quality software products. Also, by following the seven principles outlined above, it becomes possible to make the testing process more efficient. We hope that this article has helped you gain insights into software testing principles. You can post your queries in the comments section below if any.

    Frequently Asked Questions

    1. Why should you follow software testing principles?

    The software testing principles help you improve your testing strategy and the efficiency of the testing process. Also, you can perform testing on software products with less effort and in less time. Therefore, following the software testing principles help you to streamline and smoothen your testing process.

    2. What are the objectives of software testing?

    The following are the primary objectives of software testing:

    • Finding defects or bugs in the software product.
    • Ensuring that the final product matches the business or end user's requirements.
    • Ensuring that the software product functions as expected.
    • Preventing defects in the software product.
    • Ensuring that the software product is of high quality.

    3. What is software testing methodology?

    The software testing methodology is a structured and defined approach used to test applications to ensure they function as expected and comply with clients' requirements. Several testing methodologies or techniques are available that quality assurance professionals or testers can use to test applications, such as unit testing, integration testing, usability testing, compatibility testing, to name a few.

    4. What are the two major types of testing?

    The two major types of testing are functional testing and non-functional testing. Functional testing involves testing the software product to validate its functional requirements and specifications. On the flip side, non-functional testing involves testing the system to ensure its meets non-functional requirements and specifications.

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