Introduce conformance test harness

Draft
HE
2mo ago
+4581-83

The foundation for executing gvisor and LTP conformance test suite.

Summary by cubic

Adds a conformance harness for comparing elfuse with a QEMU Linux reference against checked-in expectations, with hermetic fake tests covering the framework before real suites land.

Harness

  • Supports elfuse, qemu, and host backends and records exits, signals, timeouts, and transport failures.
  • Uses canonical IDs, JSONC selection and expectation files, bidirectional judging, quarantined retries, isolated reruns, and result reports.
  • Verifies pinned payloads with content fingerprints and ELF64 checks, and provides pin-drift checks and expectation seeding.
  • Exposes scripts/conformance and Make targets with stable exit codes, including optional-prerequisite skips and --require.

Integration

  • Adds hermetic fake-suite selftests to make check; gVisor and LTP providers remain follow-ups.
  • Adds a dedicated Conformance workflow with a stable required gate that reaches every macOS job and can report pin drift.
  • Extends tests/qemu-runner.sh with stateful start/stop so QEMU can outlive its launching shell, and documents setup and operations.