llm-ingestion-okf/tests/fixtures/make_fixtures.py
Kjell Tore Guttormsen 658b7aafe0 feat(extract): implement pdf behind the [extract] extra with pdfplumber
Order G2a. Populates the optional `[extract]` extra for the first time with
one parser, `pdfplumber>=0.11.10,<0.12` (MIT), and wires `pdf` through it.
The default install is untouched: exactly one runtime dependency, stdlib
otherwise, enforced by test_packaging.py.

The gate for `pdf` becomes an import probe rather than a frozenset membership
test, exactly as extract.py's docstring had promised. The rejection does not
change: without the extra, `pdf` still raises `extractor_extra_missing` with
the same message. That behaviour is asserted UNCONDITIONALLY via a sys.modules
monkeypatch, so it holds on machines where the parser is installed too — a
skip would have preserved nothing there. Verified in a clean venv without the
extra: 589 passed, 7 skipped; with it, 596 passed.

`docx`/`xlsx` are unchanged and still fail fast — the extra names exactly what
it ships.

The parser choice was forced by measurement, not preference (b73dd9d,
docs/2026-08-21-g2-pdf-extraction-measurement.md): on a real requirement table
pdfplumber keeps 4 of 4 rows with label and value on one line, where pypdf,
pdfminer.six and pymupdf each keep 0 of 4. pymupdf is additionally out on
licence (AGPL-3.0), which an MIT package must not push onto a consumer.

Three facts from that measurement are now carried in code rather than in a
report:

- Extracted text is pinned to an exact transitive parser version
  (pdfplumber pins pdfminer.six==20260107; date-stamped, no stability
  contract). tests/test_extract.py freezes the expected text of a committed
  hand-written fixture so a parser upgrade breaks something visible instead of
  drifting silently. Reasoning at the declaration site and in
  tests/fixtures/README.md.
- Determinism within a version is now held by a test, not only measured once.
- Drawn content does not survive extraction. Every pdf extraction emits the
  new `ExtractionWarning`: figures have no text to recover, so a bundle built
  from drawn documents is incomplete by construction. Stated categorically
  rather than detected — deciding "is there a figure here" is the layout
  heuristic G2b declined.

Two new error codes, both mirroring existing patterns: `extractor_empty_pdf`
(a scanned/image-only PDF, refused rather than persisted as an empty concept)
and `extractor_pdf_error` (parser failure wrapped, never leaked).

Structured table recovery (G2b) is NOT implemented and is documented as out of
scope: two independent parsers return the same wrong shape, so the breakage is
document geometry, not a library choice. PDFs enter as prose.

Also corrects an install promise this change would otherwise have published:
the README no longer presents a bare `pip install 'llm-ingestion-okf[extract]'`
as working, because the package is not on an index.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HtNhsdHnMGtMi7U2mvMU8z
2026-08-21 20:22:39 +02:00

64 lines
2.5 KiB
Python

"""Regenerate the committed PDF fixtures for tests/test_extract.py.
Hand-written minimal PDFs: objects laid out by hand, xref offsets computed
from the emitted bytes. No generator library, so the fixtures are auditable
byte for byte and reproducible from this file alone.
Run from the repository root: python3 tests/fixtures/make_fixtures.py
"""
from __future__ import annotations
from pathlib import Path
HERE = Path(__file__).parent
# Two text lines: a heading, and one requirement row with label and value on
# the SAME line. That pairing is the property the parser choice was made on
# (see docs/2026-08-21-g2-pdf-extraction-measurement.md), so the fixture
# fails visibly if a parser upgrade ever breaks it. Byte 0xE5 is the Norwegian
# 'a-ring' in WinAnsiEncoding, which the font object below declares.
KRAV_CONTENT = (
b"BT /F1 12 Tf 20 160 Td (Krav til helning p\xe5 utkilingen) Tj ET\n"
b"BT /F1 12 Tf 20 140 Td (60 og 70 1:15) Tj ET\n"
)
# A structurally valid page carrying no text operators at all -- the shape a
# scanned or image-only PDF presents to a text extractor.
NO_TEXT_CONTENT = b"20 20 160 160 re S\n"
def build_pdf(content: bytes) -> bytes:
"""Assemble a one-page PDF around `content` as the page content stream."""
objects = [
b"<< /Type /Catalog /Pages 2 0 R >>",
b"<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
b"<< /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] "
b"/Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >>",
b"<< /Length " + str(len(content)).encode() + b" >>\nstream\n" + content + b"endstream",
b"<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>",
]
out = bytearray(b"%PDF-1.4\n")
offsets = []
for number, body in enumerate(objects, start=1):
offsets.append(len(out))
out += str(number).encode() + b" 0 obj\n" + body + b"\nendobj\n"
xref_at = len(out)
size = str(len(objects) + 1).encode()
out += b"xref\n0 " + size + b"\n0000000000 65535 f \n"
for offset in offsets:
out += ("%010d 00000 n \n" % offset).encode()
out += b"trailer\n<< /Size " + size + b" /Root 1 0 R >>\n"
out += b"startxref\n" + str(xref_at).encode() + b"\n%%EOF\n"
return bytes(out)
if __name__ == "__main__":
for name, content in (
("two-line-krav.pdf", KRAV_CONTENT),
("no-text-layer.pdf", NO_TEXT_CONTENT),
):
(HERE / name).write_bytes(build_pdf(content))
print(f"wrote {name}")