Test Techniques
Core concepts
Test techniques help select test conditions and cases. Black-box techniques use specifications: equivalence partitioning divides inputs into classes expected to behave alike; boundary value analysis tests edges; decision tables capture combinations of conditions and actions; state transition testing covers valid and invalid transitions; use case testing exercises user journeys. White-box techniques use structure: statement coverage executes each statement; branch coverage executes each decision outcome; path coverage follows paths but can be infeasible or explode combinatorially. Experience-based techniques include error guessing, exploratory testing, and checklists. Collaboration-based approaches such as ATDD derive tests from examples before implementation.
Technique choice depends on risk, test basis, coverage needs, and context. Coverage measures the proportion of specified items exercised, not proof of quality.
Traps
Candidates confuse equivalence partitioning with boundary values, or assume 100% statement coverage implies 100% branch coverage (it does not). For boundary values, use 2-value or 3-value analysis as specified. Decision tables must cover combinations, not just single rules. State transition tests include invalid events where risk warrants. Path coverage is rarely exhaustive.
Worked example
For valid ages 18–65, equivalence partitions are below 18, 18–65, and above 65. Two-value boundary tests: 17, 18, 65, 66. Three-value boundary tests add 19 and 64: 17, 18, 19, 64, 65, 66. One test per partition is not enough; add boundaries.
Rule of thumb: partition to reduce cases, then boundary-test the edges.