Function extract_error_snippet

ci/util/test_runner.py:178–252

Extract relevant error snippets from process output. Searches for lines containing actual error messages (not compiler flags like -Werror) and extracts context around the first few occurrences. Always includes the tail of the output to ensure failure summaries are visible.

(accumulated_output: list[str], context_lines: int = 5)

def extract_error_snippet(accumulated_output: list[str], context_lines: int = 5) -> str:
    """
    Extract relevant error snippets from process output.

    Searches for lines containing actual error messages (not compiler flags
    like -Werror) and extracts context around the first few occurrences.
    Always includes the tail of the output to ensure failure summaries are
    visible.

    Args:
        accumulated_output: List of output lines from the process
        context_lines: Number of lines to capture before/after each error line (default: 5)

    Returns:
        Formatted string containing error snippets with tail context
    """
    if not accumulated_output:
        return "No output captured"

    error_snippets: list[str] = []

    # Find all lines that contain real error indicators
    error_line_indices: list[int] = []
    for i, line in enumerate(accumulated_output):
        if _is_real_error_line(line):
            error_line_indices.append(i)

    # Always capture tail of output (last 30 lines) for failure summaries
    tail_count = 30
    tail_start = max(0, len(accumulated_output) - tail_count)

    if not error_line_indices:
        # No specific errors found, return tail which often has useful info
        max_lines = min(tail_count, len(accumulated_output))
        return (
            "No specific error lines found. Last "
            + str(max_lines)
            + " lines:\n"
            + "\n".join(accumulated_output[-max_lines:])
        )

    # Extract context around first 10 errors
    max_errors_to_show = 10
    shown_lines: set[int] = set()

    for error_idx in error_line_indices[:max_errors_to_show]:
        start_idx = max(0, error_idx - context_lines)
        end_idx = min(len(accumulated_output), error_idx + context_lines + 1)

        snippet_lines: list[str] = []
        for j in range(start_idx, end_idx):
            if j not in shown_lines:
                line_marker = "➤ " if j == error_idx else "  "
                snippet_lines.append(f"{line_marker}{accumulated_output[j]}")
                shown_lines.add(j)

        if snippet_lines:
            error_snippets.append("\n".join(snippet_lines))