225f96c241
The extract_markdown stub was calling extract_text instead of extract_text_fn, causing a compilation error. This fixes the function name to match the exported function from extract_text.rs. This completes the extract_text PyO3 entry point implementation, which was already present in extract_text.rs and lib.rs. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
78 lines
2.7 KiB
Markdown
78 lines
2.7 KiB
Markdown
# Fingerprint Reproducibility Test Fixtures
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This directory contains fixture pairs that verify the fingerprint algorithm's reproducibility and content-sensitivity properties.
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## Fixture Provenance
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All fixtures are generated from a clean source PDF (`.clean_source.pdf`) created using `pikepdf`, a Python library for PDF manipulation. The source is a 3-page PDF with Lorem Ipsum text, created with minimal metadata.
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## Generation
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Fixtures are generated using `generate_fingerprint_fixtures.py`, which requires:
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- Python 3.11+
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- `pikepdf` library (install via nix-shell or pip)
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```bash
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nix-shell --pure --packages python3 python3Packages.pikepdf --run \
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'python3 tests/fingerprint/fixtures/generate_fingerprint_fixtures.py'
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```
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## Fixture Pairs
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Each fixture pair contains:
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- `v1.pdf` - Original or first variant
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- `v2.pdf` - Second variant (modified copy or re-saved version)
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- `expected.txt` - Either "MATCH" (fingerprints should be identical) or "DIFFER" (fingerprints should differ)
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### 1. byte_identical
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**Expected: MATCH**
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- Same PDF copied twice (verifies fingerprint determinism)
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### 2. acrobat_resave
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**Expected: MATCH**
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- Simulates Acrobat re-save using qpdf
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- Changes `/CreationDate`, `/ID`, and xref byte layout
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- Preserves content (metadata-only changes should not affect fingerprint per ADR-008)
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### 3. pdftk_resave
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**Expected: MATCH**
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- Simulates pdftk re-save using qpdf
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- Changes object stream layout and compression
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- Content should produce identical fingerprint
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### 4. qpdf_resave
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**Expected: MATCH**
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- Same source through qpdf with `--object-streams=preserve --normalize-content=y`
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- Verifies qpdf re-save produces same fingerprint
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### 5. linearization_toggle
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**Expected: MATCH (KU-7)**
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- Unlinearized PDF vs `qpdf --linearize` output
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- Different byte layouts but same content
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- Verifies linearization independence (KU-7 requirement)
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### 6. metadata_only
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**Expected: MATCH (ADR-008)**
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- Original vs copy with changed `/Title`, `/Author`, `/Producer`, `/CreationDate`
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- Verifies metadata independence per ADR-008
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### 7. content_edit_one_glyph
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**Expected: DIFFER**
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- "Hello World" vs "Hello Worl" (one character removed)
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- Verifies content-sensitivity: removing a single glyph changes fingerprint
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### 8. content_edit_one_paragraph
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**Expected: DIFFER**
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- Original paragraph vs variant with one word changed
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- Verifies content-sensitivity: paragraph edit changes fingerprint
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## License
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The fixture PDFs are generated using MIT-licensed tools (pikepdf, qpdf) and contain public-domain text (Lorem Ipsum). Fixtures are MIT-licensed.
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## References
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- ADR-008: Metadata independence
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- KU-7: Linearization independence
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- INV-3: Fingerprint reproducibility (100 invocations produce identical results)
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- INV-13: Fingerprint format (`^pdftract-v1:[0-9a-f]{64}$`)
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