# 18. Performance Testing (XCTestMetric)

meta:
  id: ios-production-18
  feature: ios-production
  priority: P2
  depends_on: []
  tags: [testing, performance, quality]

objective:
- Implement performance testing using XCTestMetric to ensure consistent 60fps and fast response times

deliverables:
- Performance tests for critical flows
- XCTMetric measurements
- Baseline performance documentation
- Performance regression detection in CI

steps:
1. Set up performance tests:
   - Create XCTestCase with measure blocks
   - Use XCTClockMetric for time measurements
   - Use XCTCPUMetric for CPU usage
   - Use XCTMemoryMetric for memory usage
2. Test critical flows:
   - App launch time (cold and warm)
   - Dashboard scroll performance (60fps)
   - Alert list scroll performance
   - Service screen transitions
   - API response time (with mocked data)
   - Image loading performance
3. Establish baselines:
   - Run tests 10 times to establish baseline
   - Document expected ranges for each metric
   - Set performance budgets
4. Add regression detection:
   - Configure XCTest to fail on 10% regression
   - Add to CI pipeline
   - Alert on performance degradation
5. Test on physical devices:
   - iPhone SE (2nd gen) — minimum supported device
   - iPhone 12 — mid-range target
   - iPhone 15 Pro — high-end target
6. Document performance:
   - Create docs/PERFORMANCE.md
   - List all measured metrics and baselines
   - Document optimization techniques used

tests:
- Performance: All metrics within budget
- Regression: 10% regression triggers failure
- Device: Tests pass on physical devices

acceptance_criteria:
- 10+ performance test cases
- App launch time measured and baselined
- Scroll performance tested (target 60fps)
- API response time measured
- Memory usage tracked during key flows
- Baselines established for iPhone SE, 12, and 15 Pro
- 10% regression threshold configured
- Performance tests run in CI
- Performance budget documented
- No performance regressions in release builds

validation:
- Run performance tests → all within budget
- Introduce slow animation → test fails
- Check CI → performance tests passing
- Review docs → baselines documented

notes:
- Performance tests should run on physical devices, not simulators
- Simulators don't reflect real-world performance accurately
- Use Xcode's Metrics tab to track performance over time
- Consider using Firebase Performance Monitoring for real-world data