Extract and store a value from string using REGEXP

extract_and_store.rb

require 'minitest/autorun'

class ExtractAndSortTest < MiniTest::Unit::TestCase
  def setup
    @lines = [
      'Article 1 -- (45)',
      'Article 2 -- (42)',
      'Article 3 -- (62)',
    'Article 4 -- ()'
    ]
  end


  def test_extract_comment_count_from
    assert_equal(45, extract_comment_count_from('Article 1 -- (45)'))
    assert_equal(62, extract_comment_count_from('Article 2 -- (62)'))
    assert_equal(nil, extract_comment_count_from('Article 3 -- ()'))
  end

  def test_store_comment_count
    assert_equal([45, 42, 62], store_comment_counts(@lines))
  end

  def test_sort_comment_counts
    assert_equal([62, 45, 42], sort_comment_counts(@lines))    
  end
end


def extract_comment_count_from(line)
  match = /\((\d+)\)/.match(line)
  !match.nil? ? match[1].to_i : nil
end

def store_comment_counts(lines)
  comment_counts = []

  lines.each do |line|
    comment_count = extract_comment_count_from(line)
    (comment_counts << comment_count) unless comment_count.nil?
  end
  return comment_counts
end

def sort_comment_counts(lines)
  comment_counts = store_comment_counts(lines)
  comment_counts.sort { |a, b| b <=> a }
end