Performance Testing Fundamentals (basic concepts)
What this domain tests
Performance Testing Fundamentals covers the vocabulary and purpose of performance testing: why it is a non-functional test type, how it differs from functional testing, the main test types, and how performance risk drives test design. The exam checks whether you can choose the right test type for a stated risk, not just recite definitions.
Core rules and concepts
- Performance testing evaluates speed, responsiveness, stability, and resource use under a defined workload; it is not a single test but a family of test types.
- ISO/IEC 25010 places performance efficiency under time behavior, resource utilization, and capacity.
- Load testing uses expected or peak load to confirm KPIs.
- Stress testing exceeds normal capacity to find the breaking point and observe failure and recovery.
- Spike testing applies sudden load changes to check stability and recovery.
- Endurance (soak) testing sustains a representative load for hours to expose memory leaks, connection exhaustion, and degradation.
- Capacity testing determines the maximum workload the system can handle while meeting criteria; scalability testing checks whether added capacity produces proportional improvement.
- A valid test needs a defined workload model, production-like environment and data, and measurable acceptance criteria.
Worked example
A ticket-sales site expects 8,000 concurrent users during a 10-minute on-sale, with 95th-percentile response under 4 s and fewer than 0.5% errors. A load test at 8,000 validates the KPI. A spike test from 1,000 to 10,000 checks recovery. A stress test above 8,000 finds the breaking point. An endurance test at 70% of peak for 8 hours detects leaks. Each test answers a different risk; a single load test would not prove headroom or long-run stability.
Traps
Treating performance testing as synonymous with load testing; using stress results as capacity proof; starting without thresholds; testing in a scaled-down environment and extrapolating without justification.