feat : feature/issue 90 load test validation

[luhrhenz]

closes #167

summary

Load Test Validation Suite

Description

Implements automated validation of load testing results to ensure performance benchmarks are met and detect performance regressions.

Changes

• Created tests/load_validation_test.rs with 11 test cases that parse k6 JSON output
• Added tests/load/run_validation.sh helper script for running tests
• Added comprehensive documentation in tests/load/VALIDATION_README.md and tests/load/QUICKSTART.md

Features

Validates Performance Metrics

• P95 latency under threshold (500ms sustained, 1000ms spike)
• P99 latency under threshold (1000ms sustained, 2000ms spike)
• Error rate under threshold (5% sustained, 10% spike, 2% soak)
• Throughput meets minimum (10 req/s sustained, 5 req/s spike)
• Database connections within limits (200 max)
• Memory usage stable (1024 MB max)
• CPU usage reasonable (90% sustained, 95% spike)

Test Cases

1. test_p95_latency_under_threshold - Validates 95th percentile latency
2. test_p95_latency_exceeds_threshold - Tests failure detection
3. test_error_rate_under_threshold - Validates error rate
4. test_error_rate_exceeds_threshold - Tests error detection
5. test_throughput_meets_minimum - Validates throughput
6. test_db_connections_within_limits - Validates DB limits
7. test_memory_usage_stable - Validates memory stability
8. test_cpu_usage_reasonable - Validates CPU usage
9. test_percentile_calculation - Tests calculation logic
10. test_spike_test_thresholds - Validates spike thresholds
11. test_soak_test_thresholds - Validates soak thresholds

Usage

# Run load test with JSON output
docker-compose -f docker-compose.load.yml up -d app
docker-compose -f docker-compose.load.yml run --rm k6 run \
  --out json=results.json /scripts/callback_load.js

# Validate results
cargo test --test load_validation_test

# Or use helper script
./tests/load/run_validation.sh callback_load

Testing

All tests pass:

cargo test --test load_validation_test
# running 11 tests
# test result: ok. 11 passed; 0 failed

Code formatted and ready for CI:

cargo fmt --check  # ✓ passes

Documentation

• tests/load/VALIDATION_README.md - Full documentation with CI/CD examples
• tests/load/QUICKSTART.md - 5-minute getting started guide
• Inline code documentation and comments