Kjell Tore Guttormsen
66a44f173b
Three hand-laid OOXML containers, every part written out by hand and zipped
with a fixed date_time so they are byte-reproducible. No converter output
anywhere in them: a .docx written by the converter and read by the converter
proves only that the converter agrees with itself, and would stay green through
any conversion defect that is symmetric -- which is most of them.
two-line-krav.docx heading + label/value on one line (the docx mirror of
the PDF fixture)
no-styles-krav.docx the SAME document without word/styles.xml
two-line-krav.xlsx sheet name as heading + label/value on one row
THE FIXTURES FOUND A REAL DEFECT IN THE SEAM THEY WERE MEANT TO PIN. The
converter call used pypandoc's TEXT entry point, which takes an `encoding`
because it treats its source as text -- and that corrupts a zip. The xlsx
fixture failed with `Failed to unpack XLSX archive: not enough bytes` while
reading correctly from disk with the same binary. The docx of the same shape
happened to survive, which is the part worth writing down: the defect is silent
for some inputs and fatal for others, so "it worked on the file I tried" was
never evidence. Input now goes through a temporary file.
Two measurements while building, both the same shape -- structurally valid
input, silently reduced output, exit code 0, no warning:
- Without word/styles.xml the docx extracts as flat prose with no heading. A
fixture lacking that part would pin the body and pin nothing about structure.
Committed as a negative control that RUNS rather than a sentence in a README.
- With inline strings rather than a shared string table, the xlsx extracts with
the sheet name intact and every cell value gone. The fixture uses a dimension
element and a shared string table instead.
The frozen literals are pinned to a NAMED converter version, asserted beside
them: a frozen literal without one says "these bytes" without saying what
produced them.
Suite 908 -> 913. Fixtures regenerate byte-identically.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
90 lines
4.6 KiB
Markdown
90 lines
4.6 KiB
Markdown
# Test fixtures
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## The PDF fixtures
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`two-line-krav.pdf` and `no-text-layer.pdf` are hand-written minimal PDFs,
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regenerated by `make_fixtures.py` in this directory:
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```
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python3 tests/fixtures/make_fixtures.py
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```
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They carry no library's output — the objects are laid out by hand and the xref
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offsets computed from the emitted bytes — so they are auditable byte for byte
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and reproducible from that one file.
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| Fixture | What it is for |
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| `two-line-krav.pdf` | One heading plus one requirement row with label and value on the **same line**. That pairing is the property `pdfplumber` was chosen for. |
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| `no-text-layer.pdf` | A structurally valid page with no text operators — the shape a scanned or image-only PDF presents. Must fail fast (`extractor_empty_pdf`), never persist as an empty concept. |
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## The office fixtures
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`two-line-krav.docx`, `no-styles-krav.docx` and `two-line-krav.xlsx` are
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hand-laid OOXML containers, regenerated by the same `make_fixtures.py`. Every
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part is written out by hand and zipped with a fixed `date_time`, so they are
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byte-reproducible and carry no converter's output.
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**That last point is the whole policy, not a preference.** A `.docx` written by
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the converter and then read by the converter proves only that the converter
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agrees with itself, and would stay green through any conversion defect that is
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symmetric — which is most of them.
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| Fixture | What it is for |
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| `two-line-krav.docx` | A heading plus one requirement row with label and value on the **same line** — the docx mirror of `two-line-krav.pdf`. |
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| `no-styles-krav.docx` | The **same document without `word/styles.xml`**. A negative control: the body survives and the heading marker does not, which is what proves the styles part is load-bearing rather than decoration. |
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| `two-line-krav.xlsx` | A sheet name that becomes a heading, plus a label/value pair on one row. |
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Two things were measured while building these, and both are the same shape —
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structurally valid input, silently reduced output, exit code 0 and no warning:
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- **Without `word/styles.xml`** the docx extracts as flat prose with no heading.
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A fixture lacking that part would pin the body and pin nothing about
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structure, while looking exactly as convincing. Structure is the half the
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segment proposer reads.
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- **With inline strings (`t="inlineStr"`)** rather than a shared string table,
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the xlsx extracts with the sheet name intact and **every cell value gone**.
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The fixture therefore uses a `dimension` element and a shared string table.
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## Why the expected office text is frozen as a literal
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The same reason as the PDF text below, with one addition: the literals are
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pinned to a **named converter version**. `_pandoc.py` refuses any binary but
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the vendored 3.9, and `tests/test_extract.py` asserts that version beside the
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literals. A frozen literal without a named converter pins nothing — it says
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"these bytes" without saying what produced them.
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## Why the expected PDF text is frozen as a literal
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`tests/test_extract.py` asserts the extracted text of `two-line-krav.pdf` as an
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exact string. That is deliberate, and it is the mechanism behind a promise this
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library makes everywhere else:
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- Extraction is deterministic **within** a parser version. Measured 2026-08-21
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across five configurations, two runs each, compared byte for byte
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(`docs/2026-08-21-g2-pdf-extraction-measurement.md`).
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- Extraction is **not** guaranteed stable **across** parser versions.
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`pdfplumber` pins `pdfminer.six==20260107` exactly, and `pdfminer.six` ships
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date-stamped releases with no stability contract. So the real pin on extracted
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text is a transitive one, and it is exact.
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The consequence is worth stating plainly: **any golden fixture built on
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extracted PDF text is pinned to an exact parser version, and a parser upgrade
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is a fixture migration, not a routine bump.** The frozen literal is what makes
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that upgrade break something visible instead of drifting silently. If it goes
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red after a dependency change, the correct response is to read the diff and
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decide, not to re-record the expectation.
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The version range that carries this lives in `pyproject.toml`'s
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`[project.optional-dependencies] extract`, with the same reasoning at the
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declaration site.
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## What these fixtures do not cover
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Structured table recovery. Measured on real Vegnormalene, only 45 of 196
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detected table objects are clean enough to hand to `render_table` unchanged;
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two independent parsers return the same wrong shape, because the breakage is in
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the documents' ruling geometry rather than in either library. PDFs enter this
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library as **prose**, and structured tables are out of scope until that is
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decided separately.
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