You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_tsort.rb
    path of file: ./repos/jruby/test/mri
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require 'tsort'
require 'test/unit'

class TSortHash < Hash # :nodoc:
  include TSort
  alias tsort_each_node each_key
  def tsort_each_child(node, &block)
    fetch(node).each(&block)
  end
end

class TSortArray < A
    
  def test_s_each_strongly_connected_component_from
    g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
    each_child = lambda {|n, &b| g[n].each(&b) }
    r = []
    TSort.each_strongly_connected_component_from(1, each_child) {|scc|
      r << scc
    }
    assert_equal([[4], [2, 3], [1]], r)

    r = TSort.each_strongly_connected_component_from(1, each_child).map {|scc|
      scc.map(&:to_s)
    }
    assert_equal([['4'], ['2', '3'], ['1']], r)
  end