Display caught exceptions when debugging WeasyPrint

tests/css/test_validation.py

@@ -1,5 +1,6 @@
 """Test validation of properties."""
 
+import logging
 from math import pi
 
 import pytest
@@ -12,10 +13,10 @@
 from ..testing_utils import assert_no_logs, capture_logs
 
 
-def get_value(css, expected_error=None):
+def get_value(css, expected_error=None, level=None):
     declarations = tinycss2.parse_blocks_contents(css)
 
-    with capture_logs() as logs:
+    with capture_logs(level=level) as logs:
         base_url = 'https://weasyprint.org/foo/'
         declarations = list(preprocess_declarations(base_url, declarations))
 
@@ -36,13 +37,13 @@ def get_default_value(values, index, default):
     return values[index] or default
 
 
-def assert_invalid(css, message='invalid'):
-    assert get_value(css, message) is None
+def assert_invalid(css, message='invalid', level=None):
+    assert get_value(css, message, level) is None
 
 
 @assert_no_logs
 def test_not_print():
-    assert_invalid('volume: 42', 'does not apply for the print media')
+    assert_invalid('volume: 42', 'does not apply for the print media', logging.DEBUG)
 
 
 @assert_no_logs
@@ -60,7 +61,10 @@ def test_normal_prefix():
 
 @assert_no_logs
 def test_unknown_prefix():
-    assert_invalid('-unknown-display: block', 'prefixed selectors are ignored')
+    assert_invalid(
+        '-unknown-display: block',
+        'prefixed selectors are ignored',
+        logging.DEBUG)
 
 
 @assert_no_logs

weasyprint/css/__init__.py

@@ -282,9 +282,9 @@ def find_stylesheets(wrapper_element, device_media_type, url_fetcher, base_url,
                         _check_mime_type=True, media_type=device_media_type,
                         font_config=font_config, counter_style=counter_style,
                         page_rules=page_rules)
-                except URLFetchingError as exc:
-                    LOGGER.error(
-                        'Failed to load stylesheet at %s: %s', href, exc)
+                except URLFetchingError as exception:
+                    LOGGER.error('Failed to load stylesheet at %s: %s', href, exception)
+                    LOGGER.debug('Error while loading stylesheet:', exc_info=exception)
 
 
 def find_style_attributes(tree, presentational_hints=False, base_url=None):
@@ -998,9 +998,9 @@ def preprocess_stylesheet(device_media_type, base_url, stylesheet_rules,
                         media_type=device_media_type, font_config=font_config,
                         counter_style=counter_style, matcher=matcher,
                         page_rules=page_rules)
-                except URLFetchingError as exc:
-                    LOGGER.error(
-                        'Failed to load stylesheet at %s : %s', url, exc)
+                except URLFetchingError as exception:
+                    LOGGER.error('Failed to load stylesheet at %s : %s', url, exception)
+                    LOGGER.debug('Error while loading stylesheet:', exc_info=exception)
 
         elif rule.type == 'at-rule' and rule.lower_at_keyword == 'media':
             media = media_queries.parse_media_query(rule.prelude)

weasyprint/html.py

@@ -221,6 +221,7 @@ def handle_svg(element, box, get_image_from_uri, base_url):
         image = SVGImage(element, base_url, url_fetcher, context)
     except Exception as exception:  # pragma: no cover
         LOGGER.error('Failed to load inline SVG: %s', exception)
+        LOGGER.debug('Error while loading inline SVG:', exc_info=exception)
         return []
     else:
         return [make_replaced_box(element, box, image)]

weasyprint/images.py

@@ -285,8 +285,9 @@ def draw(self, stream, concrete_width, concrete_height, image_rendering):
             self._svg.draw(
                 stream, concrete_width, concrete_height, self._base_url,
                 self._url_fetcher, self._context)
-        except BaseException:
+        except BaseException as exception:
             LOGGER.error('Failed to render SVG image %s', self._base_url)
+            LOGGER.debug('Error while rendering SVG image:', exc_info=exception)
 
 
 def get_image_from_uri(cache, url_fetcher, options, url, forced_mime_type=None,
@@ -341,6 +342,7 @@ def get_image_from_uri(cache, url_fetcher, options, url, forced_mime_type=None,
 
     except (URLFetchingError, ImageLoadingError) as exception:
         LOGGER.error('Failed to load image at %r: %s', url, exception)
+        LOGGER.debug('Error while loading image:', exc_info=exception)
         image = None
 
     cache[url] = image

weasyprint/logger.py

@@ -34,13 +34,15 @@ def __init__(self, callback):
 @contextlib.contextmanager
 def capture_logs(logger='weasyprint', level=None):
     """Return a context manager that captures all logged messages."""
+    if level is None:
+        level = logging.INFO
     logger = logging.getLogger(logger)
     messages = []
 
     def emit(record):
         if record.name == 'weasyprint.progress':
             return
-        if level is not None and record.levelno < level:
+        if record.levelno < level:
             return
         messages.append(f'{record.levelname.upper()}: {record.getMessage()}')
 

weasyprint/pdf/anchors.py

@@ -347,6 +347,7 @@ def write_pdf_attachment(pdf, attachment, compress):
                 stream += data
     except URLFetchingError as exception:
         LOGGER.error('Failed to load attachment: %s', exception)
+        LOGGER.debug('Error while loading attachment:', exc_info=exception)
         return
     attachment.md5 = md5(stream, usedforsecurity=False).hexdigest()