Seven Testing Principles

There are several testing principles identified by several parties during past years. Seven are identified as most common among those.

1. Testing shows the presence of defects.

Testing can show the available defects in the software but cannot prove that there are no defects. Although the tests are concluded with no errors, cannot guarantee that the software is error free. Testing reduces the risks that can occur due to undiscovered errors.

2. Testing everything is not feasible

Testing all combinations of pre-conditions and inputs is not feasible. Simply exhaustive testing cannot be approached. Have to prioritize the scenarios and risk analysis should be focused.

3. To find defects early, start testing early

If the defects should be found as early as possible, testing should be started early.

4. Defect Clustering

Testing should be focused on early found defect density and should be compared with expected results.

5.  If the same tests are repeated, there will be no new defects found

Test cases should be regularly revised and updated. Because, software changes. If the same sets of test cases are run over and over it will find no defects. Have to be updated with new scenarios. (pesticide paradox)

6. Testing is done differently in different contexts

Testing is context dependent.

7. Absence of errors fallacy

Finding and fixing defects will not be helpful if the system is not usable by the users and if it doesn’t fit to user expectations.

Source - http://www.istqb.org/