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- """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.
- """
- import os
- from typing import List
- from typing import Optional
-
- from _pytest.nodes import Item
-
-
- DEFAULT_MAX_LINES = 8
- DEFAULT_MAX_CHARS = 8 * 80
- USAGE_MSG = "use '-vv' to show"
-
-
- def truncate_if_required(
- explanation: List[str], item: Item, max_length: Optional[int] = None
- ) -> List[str]:
- """Truncate this assertion explanation if the given test item is eligible."""
- if _should_truncate_item(item):
- return _truncate_explanation(explanation)
- return explanation
-
-
- def _should_truncate_item(item: Item) -> bool:
- """Whether or not this test item is eligible for truncation."""
- verbose = item.config.option.verbose
- return verbose < 2 and not _running_on_ci()
-
-
- def _running_on_ci() -> bool:
- """Check if we're currently running on a CI system."""
- env_vars = ["CI", "BUILD_NUMBER"]
- return any(var in os.environ for var in env_vars)
-
-
- def _truncate_explanation(
- input_lines: List[str],
- max_lines: Optional[int] = None,
- max_chars: Optional[int] = None,
- ) -> List[str]:
- """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 += f" ({truncated_line_count} line hidden)"
- else:
- msg += f" ({truncated_line_count} lines hidden)"
- msg += f", {USAGE_MSG}"
- truncated_explanation.extend(["", str(msg)])
- return truncated_explanation
-
-
- def _truncate_by_char_count(input_lines: List[str], max_chars: int) -> List[str]:
- # 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
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