Detailed Explanation of 7 Software Testing Principles

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Duc Le

Relia Software


7 software testing principles are: 1. Testing shows the presence of defects; 2. Exhaustive testing is impossible; 3. Early testing; 4. Defect clustering, etc.

software testing principles

Table of Contents

Software testing is the process of implementing software or an application to detect defects or bugs. It evaluates software based on system specs and user requirements. The software development life cycle (SDLC) includes software testing at every stage. It can also be done in program modules.

To test an application or software, you must adhere to certain rules to ensure that your product is free of flaws. This also allows test engineers to test the software with less work and time. Let’s explore 7 software testing principles that you should remember in this blog. Check it out!

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7 principles of software testing
7 Software Testing Principles (Source: Internet)

Principle 1: Testing Shows the Presence of Defects

The first principle of software testing is to help uncover bugs and errors in the software, but not to fix them. These bugs can cause unexpected behavior, incorrect calculations, security vulnerabilities, and slow performance.

The testers play a crucial role in finding and reporting these bugs early in development. This allows developers to fix them before the software reaches users. Fixing bugs early is much faster and cheaper than fixing them later in the development process.

Testers just focus on identifying issues objectively, while developers use their code knowledge to diagnose and fix them. This clear separation of duties ensures efficient testing and reduces potential conflicts within the development team.


A tester has a shopping cart glitch on an e-commerce website during testing. The tester carefully describes how to reproduce the issue and intended behavior in the bug report. After receiving this report, the software developer checks the code, finds the problem, and fixes it. To verify the bug fix, the tester retests functionality.

defects in software testing
Principle 1: Testing Shows the Presence of Defects

Principle 2: Exhaustive Testing Is Impossible

This principle recognizes that exhaustive testing is impossible in software testing. Instead, it stresses prioritizing and testing high-risk regions.

Risk-based testing applies to critical software functions, user interactions, and failure spots identified in these methodologies. Testers can prioritize and build test cases for the most vulnerable locations. This method optimizes testing resource allocation and efficiency.


Secure payment processing and user authentication are high-risk functions on e-commerce websites. Testers must spend more time and money on extensive test cases for these areas. Testing alternative payment methods with different credit cards and simulating user login scenarios may reveal security weaknesses. Lower-risk functions like product descriptions may be tested less.

exhaustes testing
Exhausted Testing (Source: Internet)

Principle 3: Early Testing 

Software testing should be a priority. It should be started early in the software development life cycle and maintained throughout development. This means testing should occur from requirements gathering to deployment and beyond.

Early and ongoing testing is cheaper and easier than later phases. It also ensures that the program meets user needs and identifies issues to solve before they become serious issues. Continuous testing will make the final product more stable and reliable.


Imagine that you develop an e-commerce site. During requirements gathering, testers can apply mockups and prototypes to analyze user stories, highlight places where functions may not satisfy user needs, and confirm the design meets expectations. 

As development continues, testers can create unit testing to check individual functions and integration tests to ensure component compatibility.

>> Read more: V Model in Software Development: The model that prioritizes early testing

early testing
Early testing can save costs and efforts (Source: Internet)

Principle 4: Defect Clustering

This software testing principle emphasizes simplifying difficult problems into test cases. Granular test cases should be well-defined and target a specific program behavior. This also increases testing accuracy by isolating functionality and finding failure sources.


E-commerce checkout is complicated. Testers can divide the checkout cycle into smaller, more focused test cases instead of one huge one. Individual test cases may be validated as address entry, payment method selection, or order confirmation. A more granular methodology enables more precise testing and faster checkout issue identification.

defects clustering
Defect Clustering (Source: Internet)

Principle 5: Pesticide Paradox

Pesticide Paradox compares software testing to agricultural pesticide use. The paradox describes the ineffectiveness of using the same tests throughout time. The paradox occurs when testing teams use the same tests without adapting or diversifying. Just as pests develop resistance to pesticides over time, software can become accustomed to the same test cases. These tests become less effective at finding new vulnerabilities as the software evolves. The static test suite may find fewer faults, making the software more vulnerable to other defects.

To avoid the "Pesticide Paradox," testing teams must adapt and diversify. This requires analyzing and upgrading test cases, adding new testing methods, and considering alternative testing viewpoints.


A mobile app test suite has been operating for several months, with no new bugs discovered. The team examines and updates the test cases, introducing new ones that address various usage scenarios and edge cases. As a result, they uncover previously unnoticed flaws.

preticide paradox
Pesticide Paradox Principle (Source: Internet)

Principle 6: Test Cases Should Be Independent

This principle emphasizes the importance of writing independent test cases. Independent test cases are self-contained and don't rely on the execution of other tests. This approach helps simplify testing and debugging. If a test fails, you can isolate the problem more quickly because the test isn't dependent on the other tests’ outcomes or specific pre-conditions.

Additionally, independent tests allow for parallel testing, where multiple tests can be run simultaneously, saving time.


Imagine a well-designed e-commerce website. A test case to verify user login with valid credentials should function independently. This means the login test should be executable at any time, regardless of whether other functionalities like account registration have been tested. If the login test fails, it's easier to pinpoint the issue within the login process itself because the test isn't dependent on anything else.

independent test cases
Independent Test Case (Source: Internet)

Principle 7: Absence of Errors Fallacy

This principle highlights the importance of retesting after bug fixes. Just because a bug is reported as fixed doesn't necessarily mean it's truly resolved. Rigorous retesting is essential to ensure the fix works as intended and to prevent regressions (the re-introduction of bugs).


The tester reruns the test case after the e-commerce web developer addresses the shopping cart bug. After adding the items to the basket, checkout, and checking the total, the shopping cart should calculate appropriately. If the retest passes, the fix works. If the retest fails, the fix may be inadequate or generate a regression bug, requiring further study.

absence of errors fallacy
Absence of Errors Fallacy (Source: Internet)

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These software testing principles can help you test more efficiently, focus, and improve your testing strategy. Combining all these principles lets you maximize efficiency by efficiently using your time and efforts.

If you are looking for a software testing service, Relia Software can help! Relia Software's Software QA & Testing Services have consistently produced high-quality apps. Our highly skilled QA specialists understand industry best practices and cutting-edge testing methods to give solid, bug-free software that surpasses customer expectations. 

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