7 testing principles

Question 1

Testing shows the presence of defects

Answer 1

Testing can demonstrate the existence of defects but cannot prove that no defects are present. Even with thorough testing, some defects may remain undiscovered.

Question 2

Exhaustive testing is impossible

Answer 2

Testing every possible combination of inputs and scenarios is impractical except for the simplest systems. Prioritize testing efforts based on risks.

Question 3

Early testing saves time and money

Answer 3

Start testing as early as possible in the software development lifecycle to identify and address defects when they are cheaper and easier to fix.

Question 4

Defects cluster together

Answer 4

Most defects are often found in a small number of modules or features, following the Pareto principle (“80-20” rule).

Question 5

Beware of the pesticide paradox

Answer 5

Reusing the same test cases repeatedly stops finding new defects. Regularly review, revise, and expand test cases to remain effective.

Question 6

Testing is context-dependent

Answer 6

The approach to testing depends on the type of system being tested (e.g., safety-critical systems vs. e-commerce applications).

Question 7

Absence-of-errors fallacy

Answer 7

Finding no defects does not mean the system is ready for use. Ensure the system meets user needs and requirements, not just that it is defect-free.