The summary.
MOST DEFECTS OCCUR AT BOUNDARIES
Test the boundary, one below and one above. Always test empty, zero, one, maximum, and maximum plus one — code handling zero and many frequently mishandles exactly one.
DECISION TABLES REVEAL COMBINATIONS THE SPECIFICATION NEVER ADDRESSED
Which become whatever the code happens to do. And pairwise testing covers most real defects, since few involve more than two interacting factors.
CHALLENGE ANY REQUIREMENT USING FAST, ROBUST, USER-FRIENDLY OR SECURE
They have no criterion, so they cannot be tested. Ask what figure would count.
WRITE A NEGATIVE CASE FOR EVERY REQUIREMENT
Requirements describe success; failure is assumed and therefore untested.
BREAK THE BEHAVIOUR ONCE TO CONFIRM THE TEST FAILS
A test that passes regardless of the code verifies nothing.
EXPLORATORY TESTING NEEDS A CHARTER, A TIME BOX AND NOTES
That is what separates it from unstructured clicking. It finds what scripts cannot, because scripts encode only what was anticipated.
AUTOMATED ACCESSIBILITY CHECKS FIND A MINORITY OF REAL PROBLEMS
Navigate the application with a screen reader yourself, and operate every function by keyboard.
