def match(pattern, source)
  ruby_version = RUBY_VERSION.to_f
  node_pattern = NodePattern.new(pattern)
  ast = RuboCop::ProcessedSource.new(source, ruby_version).ast
  node_pattern.match(ast)
end

match('(send nil? :sum $...)', 'sum(1,2,3,n)')
# => [s(:int, 1), s(:int, 2), s(:int, 3), s(:send, nil, :n)]