class SimpleCov::SourceFile

def covered_strength
  return 0.0 if lines.length.zero? || lines.length == never_lines.count
  lines_strength = 0
  lines.each do |c|
    lines_strength += c.coverage if c.coverage
  end
  effective_lines_count = Float(lines.count - never_lines.count - skipped_lines.count)
  if effective_lines_count.zero?
    0.0
  else
    strength = lines_strength / effective_lines_count
    round_float(strength, 1)
  end
end