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changedetection.io/changedetectionio/tests/unit/test_extract_title.py
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Python

#!/usr/bin/env python3
# coding=utf-8
"""Unit tests for html_tools.extract_title — including regression for #4217.
Issue #4217: extract_title silently returns None for pages where <title> is
pushed past the hard-coded 8 192-character scan window by large <head> content
(e.g. Amazon product pages where <title> can sit at character index 55 000+).
"""
import unittest
from changedetectionio.html_tools import extract_title
def _make_large_head_page(title: str, filler_count: int = 500) -> bytes:
"""Build a synthetic HTML page whose <title> is pushed far past 8 192 chars.
Each filler line is ~126 bytes; 500 lines ≈ 63 000 bytes before <title>.
"""
filler_line = '<meta name="x" content="' + "A" * 100 + '"/>\n'
head_junk = filler_line * filler_count
page = (
f"<html><head>{head_junk}"
f"<title>{title}</title>"
f"</head><body></body></html>"
)
return page.encode("utf-8")
class TestExtractTitle(unittest.TestCase):
# ------------------------------------------------------------------
# Regression: issue #4217 — large <head> pushes <title> past scan limit
# ------------------------------------------------------------------
def test_large_head_bytes_title_extracted(self):
"""<title> beyond 8 192 bytes must still be extracted (bytes input)."""
page = _make_large_head_page("Amazon Product Title - Real Title Here")
title_pos = page.find(b"<title")
self.assertGreater(
title_pos,
8192,
f"Precondition: <title> must be past 8 192 chars (actual: {title_pos})",
)
result = extract_title(page)
self.assertEqual(result, "Amazon Product Title - Real Title Here")
def test_large_head_str_title_extracted(self):
"""<title> beyond 8 192 chars must still be extracted (str input)."""
page_bytes = _make_large_head_page("Large Head String Test")
page_str = page_bytes.decode("utf-8")
title_pos = page_str.find("<title")
self.assertGreater(title_pos, 8192)
result = extract_title(page_str)
self.assertEqual(result, "Large Head String Test")
def test_very_large_head_55000_chars(self):
"""Simulate Amazon-like pages where <title> is at ~55 000 chars."""
# Use a filler that puts the title at ~55 000 chars
filler_line = '<meta name="description" content="' + "B" * 200 + '"/>\n'
filler_count = 230 # ~235 bytes * 230 ≈ 54 050 chars before <title>
head_junk = filler_line * filler_count
page = (
f"<html><head>{head_junk}"
f"<title>ASIN B0B9CGQ14V - Echo Dot (5th Gen)</title>"
f"</head><body>body content</body></html>"
).encode("utf-8")
title_pos = page.find(b"<title")
self.assertGreater(title_pos, 8192, f"<title> at {title_pos}, expected > 8192")
result = extract_title(page)
self.assertEqual(result, "ASIN B0B9CGQ14V - Echo Dot (5th Gen)")
# ------------------------------------------------------------------
# Baseline: small pages must continue to work
# ------------------------------------------------------------------
def test_normal_small_page(self):
"""Standard small page should extract title correctly."""
page = b"<html><head><title>Simple Page</title></head><body>text</body></html>"
self.assertEqual(extract_title(page), "Simple Page")
def test_str_input_small_page(self):
"""str input small page."""
page = "<html><head><title>String Input</title></head><body></body></html>"
self.assertEqual(extract_title(page), "String Input")
# ------------------------------------------------------------------
# Edge cases
# ------------------------------------------------------------------
def test_no_title_tag_returns_none(self):
"""No <title> in document → None."""
page = b"<html><head></head><body>no title here</body></html>"
self.assertIsNone(extract_title(page))
def test_empty_bytes_returns_none(self):
"""Empty bytes → None."""
self.assertIsNone(extract_title(b""))
def test_html_entities_decoded(self):
"""HTML entities inside <title> must be decoded."""
page = b"<html><head><title>Caf&eacute; &amp; Tea</title></head><body></body></html>"
self.assertEqual(extract_title(page), "Café & Tea")
def test_extra_whitespace_collapsed(self):
"""Leading/trailing/internal whitespace in title is collapsed."""
page = b"<html><head><title> Multiple Spaces </title></head><body></body></html>"
self.assertEqual(extract_title(page), "Multiple Spaces")
def test_title_with_attributes_on_tag(self):
"""<title lang="en"> (tag with attributes) must still match."""
page = b'<html><head><title lang="en">Attributed Title</title></head><body></body></html>'
self.assertEqual(extract_title(page), "Attributed Title")
def test_long_title_capped_at_2000_chars(self):
"""Titles longer than 2 000 chars are capped."""
long_title = "T" * 3000
page = f"<html><head><title>{long_title}</title></head><body></body></html>".encode()
result = extract_title(page)
self.assertIsNotNone(result)
self.assertEqual(len(result), 2000)
def test_title_300_chars_preserved(self):
"""Titles up to 2 000 chars are preserved in full."""
title = "X" * 300
page = f"<html><head><title>{title}</title></head><body></body></html>".encode()
self.assertEqual(extract_title(page), title)
def test_unsupported_type_returns_none(self):
"""Passing an unsupported type (e.g. int) returns None without raising."""
self.assertIsNone(extract_title(12345)) # type: ignore[arg-type]
def test_str_with_length_changing_lowercase_chars(self):
"""'İ'.lower() is 2 chars, the old data.lower() offset then missed the tag."""
page = "<html><head><meta name='x' content='" + "İ" * 20 + "'><title>İstanbul</title></head></html>"
self.assertEqual(extract_title(page), "İstanbul")
self.assertEqual(extract_title(page.encode("utf-8")), "İstanbul")
def test_uppercase_title_tag(self):
"""Tag matching stays case-insensitive for str and bytes."""
page = "<HTML><HEAD><TITLE>Shouty</TITLE></HEAD></HTML>"
self.assertEqual(extract_title(page), "Shouty")
self.assertEqual(extract_title(page.encode()), "Shouty")
def test_whitespace_in_tags(self):
"""Whitespace after the tag name is valid HTML, after '<' it is text (matches browsers/lxml)."""
self.assertEqual(extract_title("<head><title >A</title></head>"), "A")
self.assertEqual(extract_title("<head><title\n lang='en'>B</title></head>"), "B")
self.assertEqual(extract_title("<head><title>C</title ></head>"), "C")
self.assertEqual(extract_title(b"<head><title>D</title\n></head>"), "D")
self.assertIsNone(extract_title("<head>< title>E</title></head>"))
def test_utf32_title(self):
page = "<html><head><TITLE>Wide</TITLE></head></html>".encode("utf-32")
self.assertEqual(extract_title(page), "Wide")
def test_title_past_search_limit_is_ignored(self):
"""A <title> beyond the first 1 MiB is not searched for."""
filler = "<!-- " + "A" * (1024 * 1024) + " -->"
page = f"<html><head>{filler}<title>Too far</title></head></html>"
self.assertIsNone(extract_title(page))
self.assertIsNone(extract_title(page.encode()))
if __name__ == "__main__":
unittest.main()