"""
Utilities for truncating assertion output.
Current default behaviour is to truncate assertion explanations at
~8 terminal lines, unless running in "-vv" mode or running on CI.
"""
from _pytest.assertion.util import _running_on_ci
DEFAULT_MAX_LINES = 8
DEFAULT_MAX_CHARS = 8 * 80
USAGE_MSG = "use '-vv' to show"
[docs]def truncate_if_required(explanation, item, max_length=None):
"""
Truncate this assertion explanation if the given test item is eligible.
"""
if _should_truncate_item(item):
return _truncate_explanation(explanation)
return explanation
[docs]def _should_truncate_item(item):
"""
Whether or not this test item is eligible for truncation.
"""
level = item.config.getini("assert_truncate_level")
verbose = item.config.option.verbose
if level == "auto":
return verbose < 2 and not _running_on_ci()
return int(level) > verbose
[docs]def _truncate_explanation(input_lines, max_lines=None, max_chars=None):
"""
Truncate given list of strings that makes up the assertion explanation.
Truncates to either 8 lines, or 640 characters - whichever the input reaches
first. The remaining lines will be replaced by a usage message.
"""
if max_lines is None:
max_lines = DEFAULT_MAX_LINES
if max_chars is None:
max_chars = DEFAULT_MAX_CHARS
# Check if truncation required
input_char_count = len("".join(input_lines))
if len(input_lines) <= max_lines and input_char_count <= max_chars:
return input_lines
# Truncate first to max_lines, and then truncate to max_chars if max_chars
# is exceeded.
truncated_explanation = input_lines[:max_lines]
truncated_explanation = _truncate_by_char_count(truncated_explanation, max_chars)
# Add ellipsis to final line
truncated_explanation[-1] = truncated_explanation[-1] + "..."
# Append useful message to explanation
truncated_line_count = len(input_lines) - len(truncated_explanation)
truncated_line_count += 1 # Account for the part-truncated final line
msg = "...Full output truncated"
if truncated_line_count == 1:
msg += " ({} line hidden)".format(truncated_line_count)
else:
msg += " ({} lines hidden)".format(truncated_line_count)
msg += ", {}".format(USAGE_MSG)
truncated_explanation.extend(["", str(msg)])
return truncated_explanation
[docs]def _truncate_by_char_count(input_lines, max_chars):
# Check if truncation required
if len("".join(input_lines)) <= max_chars:
return input_lines
# Find point at which input length exceeds total allowed length
iterated_char_count = 0
for iterated_index, input_line in enumerate(input_lines):
if iterated_char_count + len(input_line) > max_chars:
break
iterated_char_count += len(input_line)
# Create truncated explanation with modified final line
truncated_result = input_lines[:iterated_index]
final_line = input_lines[iterated_index]
if final_line:
final_line_truncate_point = max_chars - iterated_char_count
final_line = final_line[:final_line_truncate_point]
truncated_result.append(final_line)
return truncated_result