test(benchmarks): implement network impairment simulation testbed and comparative benchmark harness

[archittmittal]

Objective & Overview

Build an automated simulation testbed with network impairments (packet loss, latency spikes, jitter, link resets) to evaluate and benchmark ChunkGuard / ADAPT-DL against standard tools (aria2c, wget, curl).

Technical Specification & Design

• Network Impairment Proxy: Configurable loss rates (0.5% - 10%), RTT latency (50ms - 500ms), and random socket resets.
• Benchmark Suite: Automated metrics capture:
  1. Completion Time (seconds)
  2. Goodput Speedup Ratio (x)
  3. Wasted Re-download Bandwidth (%)
  4. Tail Completion Latency (P99)
• Automated CI: GitHub Actions workflow running benchmarks and regression assertions on PRs.

Key Deliverables & Module Breakdown

• tests/simulation/impairment_server.py: Impairment proxy server
• tests/benchmarks/benchmark_runner.py: Comparison benchmark harness
• .github/workflows/benchmarks.yml: CI benchmarking workflow

Acceptance Criteria & Checkpoints

• Fault injection tests pass reliably in CI
• Automated benchmark report generates Markdown tables and speedup metrics
• Codebase achieves $\ge 90%$ test coverage

Documentation References

• Testing Strategy
• Performance Benchmarks