title: Ruby Name Error - Uninitialized constant
body: <p>I am doing <a href="http://ruby.learncodethehardway.org/book/ex47.html" rel="nofollow">exercises</a> and am
  getting <code>NameError:Unitialized Constant MyUnitTests::Room</code> when running test_ex47.rb.</p>
  
  <p>test_ex47.rb:</p>
  
  <pre><code>require 'test/unit'
  require_relative '../lib/ex47'
  
  class MyUnitTests &lt; Test::Unit::TestCase
      def test_room()
          gold = Room.new("Gold Room", """This room has gold in it you can grab. There's a doo to the north.""")
      assert_equal(gold.name, "GoldRoom")
      assert_equal(gold.paths, {})
  end
  
  def test_room_paths()
      center = Room.new("Center", "Test room in the center.")
      north = Room.new("North", "Test room in the north.")
      south = Room.new("South", "Test room in the south.")
  
      center.add_paths({:north =&gt; north, :south =&gt; south})
      assert_equal(center.go(:north), north)
      assert_equal(center.go(:south), south)
  end
  
  def test_map()
      start = Room.new("Start", "You can go west and down a hole.")
      west = Room.new("Trees", "There are trees here, you can go east.")
      down = Room.new("Dungeon", "It's dark down here, you can go up.")
  
      start.add_paths({:west =&gt; west, :down =&gt; down})
      west.add_paths({:east =&gt; start})
      down.add_paths({:up =&gt; start})
  
      assert_equal(start.go(:west), west)
      assert_equal(start.go(:west).go(:east), start)
      assert_equal(start.go(down).go(up), start)
  end
  
  end
  </code></pre>
  
  <p>ex47.rb is located in the lib folder and looks like:</p>
  
  <pre><code>class Room
  aatr_accessor :name, :description, :paths
  
  def initialize(name, description)
      @name = name
      @description = description
      @paths = {}
  end
  
  def go(direction)
      @paths[direction]
  end
  
  def add_paths(paths)
      @paths.update(paths)
  end
  end
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Finished tests in 0.000872s, 3440.3670 tests/s, 0.0000 assertions/s.
  
    1) Error:
  test_map(MyUnitTests):
  NameError: uninitialized constant MyUnitTests::Room
      test_ex47.rb:22:in `test_map'
  
    2) Error:
  test_room(MyUnitTests):
  NameError: uninitialized constant MyUnitTests::Room
      test_ex47.rb:6:in `test_room'
  
    3) Error:
  test_room_paths(MyUnitTests):
  NameError: uninitialized constant MyUnitTests::Room
      test_ex47.rb:12:in `test_room_paths'
  
  3 tests, 0 assertions, 0 failures, 3 errors, 0 skips]
  </code></pre>