94 lines
3.3 KiB
Python
94 lines
3.3 KiB
Python
"""
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Round-trip tests for diff using real snapshot records from ./tests/data/.
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For every pair of consecutive records (within a file and across adjacent files)
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we verify:
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merge_full(a, diff_full(a, b)) == b
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We also verify that diffing identical records produces an empty diff, and that
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applying an empty diff is a no-op.
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"""
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import json
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import pathlib
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import pytest
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from jaydiff.diff import diff_full
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from jaydiff.merge import merge_full
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DATA_DIR = pathlib.Path(__file__).parent / "data"
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def _load_all_records() -> list[dict]:
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"""Return all records from all data files, sorted by timestamp."""
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records: list[dict] = []
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for path in sorted(DATA_DIR.glob("*.json")):
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store = json.loads(path.read_text())
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records.extend(store.get("records", []))
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records.sort(key=lambda r: r.get("ts", ""))
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return records
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ALL_RECORDS = _load_all_records()
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CONSECUTIVE_PAIRS = list(zip(ALL_RECORDS, ALL_RECORDS[1:]))
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class TestRealDataRoundTrip:
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"""Diff+merge of every consecutive snapshot pair must reconstruct the target."""
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@pytest.mark.parametrize("pair_index", range(len(CONSECUTIVE_PAIRS)))
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def test_consecutive_round_trip(self, pair_index: int) -> None:
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a, b = CONSECUTIVE_PAIRS[pair_index]
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diff = diff_full(a, b)
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result = merge_full(a, diff)
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assert result == b, (
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f"Round-trip failed for pair #{pair_index} "
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f"(ts: {a.get('ts')} → {b.get('ts')})"
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)
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@pytest.mark.parametrize("pair_index", range(len(CONSECUTIVE_PAIRS)))
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def test_diff_of_identical_is_empty(self, pair_index: int) -> None:
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a, _ = CONSECUTIVE_PAIRS[pair_index]
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assert diff_full(a, a) == {}
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@pytest.mark.parametrize("pair_index", range(len(CONSECUTIVE_PAIRS)))
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def test_empty_diff_is_noop(self, pair_index: int) -> None:
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a, _ = CONSECUTIVE_PAIRS[pair_index]
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assert merge_full(a, {}) == a
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class TestRealDataProperties:
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"""Structural invariants on the real snapshot data."""
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def test_data_dir_has_files(self) -> None:
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assert len(list(DATA_DIR.glob("*.json"))) > 0, "No JSON files in tests/data/"
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def test_all_records_have_timestamp(self) -> None:
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for rec in ALL_RECORDS:
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assert "ts" in rec, f"Record missing 'ts': {list(rec.keys())}"
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def test_records_are_sorted(self) -> None:
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ts_list = [r["ts"] for r in ALL_RECORDS]
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assert ts_list == sorted(ts_list), "Records are not in ascending timestamp order"
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def test_total_record_count(self) -> None:
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assert len(ALL_RECORDS) > 100, (
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f"Expected >100 records across all files, got {len(ALL_RECORDS)}"
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)
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def test_diff_size_smaller_than_full_snapshot(self) -> None:
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"""Diffs between similar consecutive records should usually be smaller."""
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savings = 0
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for a, b in CONSECUTIVE_PAIRS:
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diff = diff_full(a, b)
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if diff: # skip identical pairs
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diff_len = len(json.dumps(diff))
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full_len = len(json.dumps(b))
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if diff_len < full_len:
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savings += 1
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ratio = savings / len(CONSECUTIVE_PAIRS) if CONSECUTIVE_PAIRS else 1.0
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assert ratio > 0.5, (
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f"Expected diffs to be smaller than full snapshots for >50% of pairs, "
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f"got {ratio:.0%}"
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) |