count.rb

def count_num(arr)
  arr.each_with_object({}) { |i, hash| hash[i] = arr.count(i) }
end


gem 'minitest', '>= 5.0.0'
require 'minitest/autorun'

class CountTest < Minitest::Test
  def test_count
    count = count_num([1, 1, 1, 2, 5, 5])
    correct_count = { 1 => 3, 2 => 1, 5 => 2 }
    assert_equal correct_count, count
  end
end