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| 1 | +"""Golden-output registry for determinism tests. |
| 2 | + |
| 3 | +Goldens are JSON blobs under `tests/golden/` keyed by `(name, torch_version)` |
| 4 | +so bumping torch produces a new golden rather than silently invalidating |
| 5 | +the old one (audit F19). |
| 6 | + |
| 7 | +Contract: |
| 8 | + |
| 9 | +- `assert_golden(actual, name)` compares `actual` against the stored |
| 10 | + golden; if no golden exists for the current torch version, the test |
| 11 | + fails with an instruction to regenerate. |
| 12 | +- `pytest --update-goldens` regenerates instead of asserting; the |
| 13 | + `update_goldens` fixture (`conftest.py`) surfaces the flag. |
| 14 | +- Golden content is deterministically serialized JSON (sorted keys, |
| 15 | + normalized floats). |
| 16 | +""" |
| 17 | + |
| 18 | +from __future__ import annotations |
| 19 | + |
| 20 | +import json |
| 21 | +from pathlib import Path |
| 22 | +from typing import Any |
| 23 | + |
| 24 | +GOLDEN_ROOT = Path(__file__).resolve().parent.parent / "golden" |
| 25 | + |
| 26 | + |
| 27 | +class MissingGoldenError(AssertionError): |
| 28 | + """Raised when a golden isn't on disk and we're not regenerating.""" |
| 29 | + |
| 30 | + |
| 31 | +def golden_path(name: str, *, torch_version: str | None = None) -> Path: |
| 32 | + """Resolve the on-disk path for a golden by (name, torch_version).""" |
| 33 | + tv = torch_version if torch_version is not None else _current_torch_version() |
| 34 | + # Filesystem-safe: replace periods and pluses. |
| 35 | + safe_tv = tv.replace("/", "_").replace("+", "_").replace(" ", "_") |
| 36 | + safe_name = name.replace("/", "_") |
| 37 | + return GOLDEN_ROOT / f"{safe_name}.torch-{safe_tv}.json" |
| 38 | + |
| 39 | + |
| 40 | +def load_golden(name: str, *, torch_version: str | None = None) -> Any: |
| 41 | + path = golden_path(name, torch_version=torch_version) |
| 42 | + if not path.exists(): |
| 43 | + raise MissingGoldenError( |
| 44 | + f"No golden for {name!r} at {path}. " |
| 45 | + "Run with --update-goldens to regenerate after manual review.", |
| 46 | + ) |
| 47 | + return json.loads(path.read_text(encoding="utf-8")) |
| 48 | + |
| 49 | + |
| 50 | +def assert_golden( |
| 51 | + actual: Any, |
| 52 | + name: str, |
| 53 | + *, |
| 54 | + update: bool = False, |
| 55 | + torch_version: str | None = None, |
| 56 | +) -> None: |
| 57 | + """Compare `actual` against stored golden, or regenerate when `update`. |
| 58 | + |
| 59 | + `actual` must be JSON-serializable. Regeneration writes sorted-keys |
| 60 | + output so diffs are reviewable. |
| 61 | + """ |
| 62 | + path = golden_path(name, torch_version=torch_version) |
| 63 | + |
| 64 | + if update: |
| 65 | + path.parent.mkdir(parents=True, exist_ok=True) |
| 66 | + _write_json(path, actual) |
| 67 | + return |
| 68 | + |
| 69 | + if not path.exists(): |
| 70 | + raise MissingGoldenError( |
| 71 | + f"No golden for {name!r} at {path}. " |
| 72 | + "Run `pytest --update-goldens` after manual review to create it.", |
| 73 | + ) |
| 74 | + |
| 75 | + expected = json.loads(path.read_text(encoding="utf-8")) |
| 76 | + if _canonical(expected) != _canonical(actual): |
| 77 | + diff_lines = [ |
| 78 | + f"Golden mismatch for {name!r} (path: {path}).", |
| 79 | + "Expected:", |
| 80 | + json.dumps(expected, sort_keys=True, indent=2), |
| 81 | + "Actual:", |
| 82 | + json.dumps(actual, sort_keys=True, indent=2), |
| 83 | + ] |
| 84 | + raise AssertionError("\n".join(diff_lines)) |
| 85 | + |
| 86 | + |
| 87 | +# --- internals --------------------------------------------------------------- |
| 88 | + |
| 89 | + |
| 90 | +def _current_torch_version() -> str: |
| 91 | + # Lazy import so callers that don't use goldens don't pay for torch. |
| 92 | + import torch |
| 93 | + |
| 94 | + return torch.__version__ |
| 95 | + |
| 96 | + |
| 97 | +def _canonical(value: Any) -> str: |
| 98 | + """Canonical JSON form for comparison.""" |
| 99 | + return json.dumps(value, sort_keys=True, separators=(",", ":")) |
| 100 | + |
| 101 | + |
| 102 | +def _write_json(path: Path, value: Any) -> None: |
| 103 | + text = json.dumps(value, sort_keys=True, indent=2) + "\n" |
| 104 | + path.write_text(text, encoding="utf-8") |
