79 lines
2.7 KiB
Python
79 lines
2.7 KiB
Python
 
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"""Codec tests. The heavy differential sweep against Boxsim.exe lives in
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tools/difftest.py; these guard regressions against the digests it recorded.
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"""
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from __future__ import annotations
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import hashlib
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from pathlib import Path
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import pytest
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from boxsim import a2f, container
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from boxsim.krypt import KryptPRNG
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ROOT = Path(__file__).resolve().parent.parent
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def test_keystream_is_stable():
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"""Regression guard on the keystream every Boxsim file is scrambled with.
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The value is not independently derived, it is the keystream under which all
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134 containers in the distribution decode byte-identically to Boxsim's own
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decoder (see tools/difftest.py). Its worth here is catching an accidental
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change to the generator, not proving the generator correct.
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"""
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ks = KryptPRNG().keystream(8)
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assert ks.hex() == "ebe14331cb3183e1"
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def test_rejects_foreign_file():
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with pytest.raises(container.ContainerError, match="not a MyIni2CK file"):
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container.decode(b"not a boxsim file at all")
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def test_truncated_stream_fails_loudly():
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raw = (ROOT / "boxsim_dl" / "BoxSim 2.1 DE (Stand 12.2025)"
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/ "Projekte" / "Default.BPJ")
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if not raw.exists():
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pytest.skip("distribution not present")
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data = raw.read_bytes()
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with pytest.raises(a2f.A2FError):
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container.decode(data[: len(data) // 2])
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def test_padding_allowance_is_bounded():
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# A stream of zeros must not decode forever; it has to hit the limit.
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with pytest.raises(a2f.A2FError):
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a2f.expand(b"MyIni2CK", skip_magic=8)
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@pytest.mark.needs_dist
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def test_matches_oracle_digests(manifest: dict):
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"""Every container the oracle decoded must still decode identically."""
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files = manifest["files"]
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assert files, "manifest has no entries"
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checked = 0
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for rel, expected in files.items():
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path = ROOT / rel
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if not path.exists():
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pytest.fail(f"manifest references missing file {rel}")
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payload = container.decode(path.read_bytes())
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digest = hashlib.sha256(payload).hexdigest()
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assert digest == expected["sha256"], f"{rel} digest changed"
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assert len(payload) == expected["len"], f"{rel} length changed"
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checked += 1
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assert checked == len(files)
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@pytest.mark.needs_dist
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def test_pre20_containers_are_rejected(manifest: dict):
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"""The BoxSim 1.2 files use an older container and must stay rejected."""
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rejected = manifest["rejected_not_myini2ck"]
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assert rejected, "manifest recorded no rejected files"
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for rel in rejected:
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path = ROOT / rel
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if not path.exists():
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continue
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with pytest.raises(container.ContainerError):
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container.decode(path.read_bytes())
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