chore: import upstream snapshot with attribution

tests/test_office_incremental.py

@@ -0,0 +1,67 @@
+"""#1649 — a modified .docx/.xlsx must re-enter --update.
+
+detect_incremental tracks the converted markdown SIDECAR, not the Office
+source. convert_office_file used to early-return whenever the sidecar existed,
+so a source edited after its first conversion never updated its sidecar and was
+reported "unchanged" forever. It now re-converts when the source is newer than
+the sidecar (and still skips an unchanged source so it never churns, #1226).
+"""
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import pytest
+
+from graphify import detect
+
+docx = pytest.importorskip("docx")
+
+
+def _make_docx(path: Path, text: str) -> None:
+    d = docx.Document()
+    d.add_paragraph(text)
+    d.save(str(path))
+
+
+def _bump_mtime(path: Path, offset: float) -> None:
+    """Set path's mtime relative to now so ordering is deterministic."""
+    st = path.stat()
+    os.utime(path, (st.st_atime, st.st_mtime + offset))
+
+
+def test_modified_docx_reconverts_sidecar(tmp_path: Path):
+    src = tmp_path / "doc.docx"
+    out = tmp_path / "converted"
+    _make_docx(src, "original alpha content")
+
+    sidecar = detect.convert_office_file(src, out)
+    assert sidecar is not None
+    assert "original alpha content" in sidecar.read_text(encoding="utf-8")
+
+    # Edit the source and make it newer than the sidecar.
+    _make_docx(src, "revised beta content")
+    _bump_mtime(sidecar, -10)  # sidecar older than the freshly-written source
+
+    sidecar2 = detect.convert_office_file(src, out)
+    assert sidecar2 == sidecar  # same deterministic name
+    body = sidecar2.read_text(encoding="utf-8")
+    assert "revised beta content" in body
+    assert "original alpha content" not in body
+
+
+def test_unchanged_docx_sidecar_not_rewritten(tmp_path: Path):
+    src = tmp_path / "doc.docx"
+    out = tmp_path / "converted"
+    _make_docx(src, "stable content")
+
+    sidecar = detect.convert_office_file(src, out)
+    assert sidecar is not None
+    # Make the sidecar clearly newer than the (unchanged) source.
+    _bump_mtime(sidecar, 100)
+    before = sidecar.stat().st_mtime
+
+    sidecar2 = detect.convert_office_file(src, out)
+    assert sidecar2 == sidecar
+    # Not rewritten: mtime unchanged, so detect_incremental won't see churn (#1226).
+    assert sidecar2.stat().st_mtime == before