7️Testing Principles

The 7 Testing Principles are the fundamental principles that guide an effective testing approach.

The goal is to design a thorough yet feasible set of test cases that exercises the system as thoroughly as possible within time and resource constraints.

Principle	Definition	Explanation	Example
🔁 Testing shows the presence of defects	Testing can only identify the presence of defects, not their absence	Testing should be continued to ensure that all defects are caught and resolved	A defect is found during testing, corrected, and then retested
❌ Exhaustive Testing is not possible	A black box testing technique where you systematically test all possible combinations of inputs and conditions to uncover errors.	To "exhaust" 💯 all possibilities in order to have high confidence ✅ in the stability and robustness of the system.	Test valid values 🟢, invalid values 🔴, edge cases 🟠, repetition of valid/invalid values 🎡, and different combinations.
🚀 Early testing	Start testing early in the SDLC to capture and eliminate defects in the early stages	By identifying and resolving issues early on, the cost and time required for testing and rework can be significantly reduced	Testing during the requirement gathering and design phases
🔍 Defect clustering	A small number of modules usually contain most of the defects detected during pre-release testing or operation	More testing efforts can be focused on these modules, which can help to reduce the number of defects in the software	Modules that contain most of the defects are identified and more testing is focused on them
🤝 The pesticide paradox	Vary the testing techniques and methods used to ensure that all defects are caught and resolved	Repeating the same testing techniques may not catch defects that were caught and resolved initially	Using a variety of testing techniques such as unit testing, integration testing, and system testing
👨‍👩‍👦‍👦 Testing is context-dependent	Consider the context in which the software is being developed and tested	The testing approach and techniques used may vary depending on the context	Testing approaches and techniques used for web-based software may differ from those used for mobile applications
📈 Pareto principle	80% of the defects are likely to be caused by 20% of the modules	Focusing on this 20% of modules can help to improve the quality of the software	Identifying and focusing on the 20% of modules that are likely to have the most defects