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mcp-nextcloud/tests/unit/test_doc_classifier.py
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Chris CoutinhoandClaude Opus 4.8 f1272dfe84 fix(review): lock OCR backend init, warn on rollback fallthrough, zero-page metric
Address PR #858 review round 2:

- OcrProcessor backend resolution is now guarded by an anyio.Lock (lazy-init,
  double-checked) so a burst of concurrent first-OCR calls resolves the backend
  once instead of each fetching its own gateway M2M token.
- The document_tier1_engine=pymupdf rollback now logs a warning when it falls
  back to the fast processor (no 'structured' registered) instead of silently
  using the very engine the operator opted out of.
- classify_from_text defaults ocr_frac to 0.0 (not 1.0) for a zero-page PDF, so
  the recorded classification metric is "fast" (no OCR evidence) rather than a
  misleading "ocr"; the no_text_layer/bad_text_layer flags are gated on having
  sampled at least one page.

New tests: zero-page classify routes fast, rollback-fallback warning.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-05 02:24:08 +02:00

188 lines
6.3 KiB
Python

"""Unit tests for the tier-0 document classifier.
Pins the routing decisions and the text-quality heuristic that drive which
extraction tier a PDF starts in:
* a clean born-digital PDF (text, no full-page images) -> ``fast`` (tier 1);
* a full-page-image scan -> ``ocr`` (tier 3), since handwriting/stamps aren't
in any text layer;
* the text-quality score distinguishes clean prose from mashed/space-less junk.
"""
import pymupdf
import pytest
from nextcloud_mcp_server.document_processors import classifier as clf
pytestmark = pytest.mark.unit
def _digital_pdf(
pages: int = 3, body: str = "Hello world this is clean text. "
) -> bytes:
doc = pymupdf.open()
for _ in range(pages):
page = doc.new_page(width=595, height=842)
page.insert_text((50, 60), body * 8)
data: bytes = doc.tobytes()
doc.close()
return data
def _full_page_image_pdf(pages: int = 2) -> bytes:
# A page whose entire area is a raster image -> looks scanned.
doc = pymupdf.open()
pix = pymupdf.Pixmap(pymupdf.csRGB, pymupdf.IRect(0, 0, 600, 850))
pix.clear_with(255)
img = pix.tobytes("png")
del pix # Pixmap holds native memory; release it before the loop
for _ in range(pages):
page = doc.new_page(width=595, height=842)
page.insert_image(page.rect, stream=img)
data: bytes = doc.tobytes()
doc.close()
return data
# --- text-quality heuristic --------------------------------------------------
def test_text_quality_clean_prose_scores_high():
assert clf._text_quality("the quick brown fox jumps over the lazy dog") > 0.8
def test_text_quality_mashed_tokens_scores_low():
# space-less / mashed layer (the "Student 147" failure mode)
mashed = "01322234567mobileoutstandingresilienceacademicachievementhurdles"
assert clf._text_quality(mashed) < clf.MIN_TEXT_QUALITY
def test_text_quality_empty_is_zero():
assert clf._text_quality("") == pytest.approx(0.0)
# --- routing -----------------------------------------------------------------
def test_digital_pdf_routes_fast():
c = clf.classify_pdf(_digital_pdf())
assert c.recommended_tier == "fast"
assert c.ocr_page_fraction == pytest.approx(0.0)
assert "image_heavy" not in c.flags
assert c.mean_text_quality > 0.8
def test_full_page_image_routes_ocr():
c = clf.classify_pdf(_full_page_image_pdf())
assert c.recommended_tier == "ocr"
assert c.ocr_page_fraction == pytest.approx(1.0)
assert "image_heavy" in c.flags
assert "scanned" in c.flags # no text layer at all
# --- sampling bounds large docs ----------------------------------------------
def test_large_doc_is_sampled():
c = clf.classify_pdf(_digital_pdf(pages=120))
assert c.page_count == 120
assert c.sampled_pages <= clf.MAX_SAMPLED_PAGES
def test_sample_indices_includes_first_and_last_page():
idx = clf._sample_indices(100)
assert idx[0] == 0
assert idx[-1] == 99 # last page must be sampled (scanned-tail case)
assert len(idx) <= clf.MAX_SAMPLED_PAGES
# --- flag paths --------------------------------------------------------------
def _image_with_mashed_text_pdf(pages: int = 2) -> bytes:
# Full-page image with a junk (mashed/space-less) text layer over it -- a
# scan whose OCR'd text layer is unusable.
doc = pymupdf.open()
pix = pymupdf.Pixmap(pymupdf.csRGB, pymupdf.IRect(0, 0, 600, 850))
pix.clear_with(255)
img = pix.tobytes("png")
del pix # Pixmap holds native memory; release it before the loop
mashed = "01322234567mobileoutstandingresilienceacademicachievement " * 3
for _ in range(pages):
page = doc.new_page(width=595, height=842)
page.insert_image(page.rect, stream=img)
page.insert_text((50, 60), mashed)
data: bytes = doc.tobytes()
doc.close()
return data
def test_scanned_flag_when_no_text_layer():
c = clf.classify_pdf(_full_page_image_pdf())
assert c.total_chars == 0
assert "scanned" in c.flags
assert c.recommended_tier == "ocr"
def test_bad_text_layer_flag_on_image_with_junk_text():
c = clf.classify_pdf(_image_with_mashed_text_pdf())
assert c.total_chars > 0
assert c.mean_text_quality < clf.MIN_TEXT_QUALITY
assert "bad_text_layer" in c.flags
assert c.recommended_tier == "ocr"
def _mostly_text_one_image_pdf() -> bytes:
# 3 digital text pages + 1 full-page-image page: one image-heavy page, but
# ocr_frac = 1/4 < OCR_PAGE_FRACTION, so the doc routes fast.
doc = pymupdf.open()
pix = pymupdf.Pixmap(pymupdf.csRGB, pymupdf.IRect(0, 0, 600, 850))
pix.clear_with(255)
img = pix.tobytes("png")
del pix # Pixmap holds native memory; release it before the loop
for _ in range(3):
page = doc.new_page(width=595, height=842)
page.insert_text((50, 60), "Hello world this is clean text. " * 8)
page = doc.new_page(width=595, height=842)
page.insert_image(page.rect, stream=img)
data: bytes = doc.tobytes()
doc.close()
return data
def test_image_heavy_flag_without_ocr_routing():
# The documented asymmetry operators rely on: a mostly-digital doc with one
# full-page image carries the image_heavy flag yet still routes fast.
c = clf.classify_pdf(_mostly_text_one_image_pdf())
assert "image_heavy" in c.flags
assert c.recommended_tier == "fast"
assert c.ocr_page_fraction < clf.OCR_PAGE_FRACTION
# --- classify_from_text (hot-path, derived from tier-1 extraction) -----------
def test_classify_from_text_clean_routes_fast():
txt = "the quick brown fox jumps over the lazy dog " * 3
c = clf.classify_from_text(
txt, [{"page": 1, "start_offset": 0, "end_offset": len(txt)}]
)
assert c.recommended_tier == "fast"
assert c.mean_text_quality > 0.8
assert c.flags == set()
def test_classify_from_text_empty_routes_ocr():
c = clf.classify_from_text("", [{"page": 1, "start_offset": 0, "end_offset": 0}])
assert c.recommended_tier == "ocr"
assert "no_text_layer" in c.flags
assert c.total_chars == 0
def test_classify_from_text_no_pages_routes_fast():
# An empty/corrupt PDF (no page boundaries) is not OCR evidence -> "fast",
# so the recorded classification metric isn't a misleading "ocr".
c = clf.classify_from_text("", [])
assert c.recommended_tier == "fast"
assert c.ocr_page_fraction == pytest.approx(0.0)
assert c.flags == set()