SIA LESSON 3.0 PRINCIPLES OF TESTING

Testing shows the presence of Defects, not their Absence

Even if no defects are found, it doesn't mean the system is perfect

only that the tests didn't detect any problems.Testing shows that defects are present, but it cannot prove that no defects exist.

Testing shows the presence of Defects, not their Absence

After testing a login feature with valid and invalid credentials, you may not find bugs, but there could still be security loopholes

Exhaustive Testing is Impossible

Real Definition: Testing every possible input, combination, and path is not practical except for the simplest programs. Testing should be risk-based and prioritize critical functionalities and common scenarios.

Exhaustive Testing is Impossible

Real-Life Scenario: For an online payment form, instead of testing every possible currency and card type, you test the most frequently used ones and high-risk cases.

Early Testing Saves Time and Money

Real Definition: Start testing activities as early as possible in the software development life cycle (SDLC). Defects found early are cheaper and easier to fix than those found later.

Early Testing Saves Time and Money

Real-Life Scenario: Reviewing requirements or design documents before coding can catch ambiguities or inconsistencies early.

Defects Cluster Together

Real Definition: A small number of modules usually contain most of the defects. Testing should focus on these "hot spots" or high-risk areas first.

Defects Cluster Together

Real-Life Scenario: If a reporting module has had many bugs in past releases, it's likely to have more defects in future updates.

The Pesticide Paradox

Real Definition: If the same set of tests is repeated too often, it will eventually stop finding new defects. Test cases need to be regularly reviewed and updated to remain effective.

The Pesticide Paradox

Real-Life Scenario: After running the same regression test suite for months, testers should add new scenarios to uncover different issues.

Testing is Context Dependent

Testing approaches vary depending on the type of system, industry, and project.

There is no one-size-fits-all method; safety-critical systems require more rigorous testing than casual mobile apps.

Testing is Context Dependent

Real-Life Scenario: Testing a medical device software will involve stricter compliance and more thorough documentation than testing a simple game app.

Absence-of-Errors Fallacy

Finding and fixing defects does not guarantee that the system will meet user needs.

The system can be defect-free but still unusable or not aligned with business requirements.

Absence-of-Errors Fallacy

Real-Life Scenario: A hotel booking site might work perfectly but fail to allow group bookings, which customers require.