class RuboCop::Cop::Lint::FormatParameterMismatch

def expected_fields_count(node)
  return :unknown unless node.str_type?
  return 1 if node.source =~ NAMED_INTERPOLATION
  node
    .source
    .scan(FIELD_REGEX)
    .select { |x| x.first != PERCENT_PERCENT }
    .reduce(0) { |acc, elem| acc + (elem[2] =~ /\*/ ? 2 : 1) }
end