M8-T07: extract reusable P1 parser

tests/test_p1_parser.py

@@ -0,0 +1,92 @@
+from __future__ import annotations
+
+from decimal import Decimal
+import hashlib
+from pathlib import Path
+
+import pytest
+
+from app.integrations.p1 import IntegrityStatus, P1ParseError, TelegramFramer, parse_telegram
+
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def _fixture(name: str) -> bytes:
+    return (FIXTURES / name).read_bytes()
+
+
+def test_parser_preserves_fixture_quality_and_uses_only_fingerprints_for_identifiers():
+    frame = _fixture("warmtelink_p1_7n1.txt")
+    telegram = parse_telegram(frame)
+
+    assert telegram.integrity is IntegrityStatus.UNVERIFIABLE
+    assert telegram.frame_length == len(frame)
+    assert [channel.number for channel in telegram.channels] == [1, 2]
+    assert telegram.channels[0].readings[0].value == Decimal("5.900")
+    assert telegram.channels[1].readings[0].unit == "GJ"
+    assert all(field.raw_values == ("<redacted>",) for field in telegram.fields if "96.1" in field.code)
+    assert repr(telegram).find("<redacted>") >= 0
+    assert "KAM" not in repr(telegram)
+
+
+def test_parser_hashes_identifiers_without_returning_them():
+    telegram_identifier = "secret-telegram-equipment-42"
+    channel_identifier = "secret-channel-equipment-42"
+    telegram = parse_telegram(
+        f")HEADER\n0-0:96.1.1({telegram_identifier})\n"
+        f"0-1:96.1.0({channel_identifier})\n!nope\n".encode()
+    )
+
+    telegram_fingerprint = hashlib.sha256(telegram_identifier.encode()).hexdigest()
+    channel_fingerprint = hashlib.sha256(channel_identifier.encode()).hexdigest()
+    assert telegram.equipment_fingerprint == telegram_fingerprint
+    assert telegram.channels[0].equipment_fingerprint == channel_fingerprint
+    rendered = repr(telegram)
+    assert telegram_identifier not in rendered
+    assert channel_identifier not in rendered
+    assert telegram_fingerprint not in rendered
+    assert channel_fingerprint not in rendered
+
+
+def test_framer_handles_truncation_concatenation_and_variable_lengths_without_channel_mixup():
+    first = _fixture("warmtelink_p1_7n1.txt")
+    second = first.replace(b"(5.900*m3)", b"(12345.678*m3)")
+    framer = TelegramFramer()
+
+    assert framer.feed(first[:-4]) == []
+    frames = framer.feed(first[-4:] + second)
+
+    assert [parse_telegram(frame).channels[0].readings[0].value for frame in frames] == [
+        Decimal("5.900"),
+        Decimal("12345.678"),
+    ]
+
+
+def test_parser_tolerates_bad_text_without_exposing_it_and_rejects_missing_footer():
+    telegram = parse_telegram(b")HEADER\n0-1:24.2.1(1.000*m3)\n\xff\n!not-hex\n")
+    assert telegram.integrity is IntegrityStatus.UNVERIFIABLE
+    assert telegram.channels[0].readings[0].value == Decimal("1.000")
+
+    with pytest.raises(P1ParseError, match="footer marker") as exc_info:
+        parse_telegram(b"secret raw telegram")
+    assert "secret" not in str(exc_info.value)
+
+
+def test_parser_error_does_not_expose_equipment_identifiers():
+    first_identifier = "private-equipment-id-one"
+    second_identifier = "private-equipment-id-two"
+
+    with pytest.raises(P1ParseError) as exc_info:
+        parse_telegram(
+            f")HEADER\n0-0:96.1.1({first_identifier})\n"
+            f"0-1:96.1.0({second_identifier})\n".encode()
+        )
+
+    assert first_identifier not in str(exc_info.value)
+    assert second_identifier not in str(exc_info.value)
+
+
+def test_parser_keeps_standard_invalid_crc_invalid():
+    frame = _fixture("dsmr_p1_valid.txt")
+    assert parse_telegram(frame[:-5] + b"0000\n").integrity is IntegrityStatus.INVALID