1  
   2  require 'test/unit'
   3  
   4  class Object
   5    def self.subclasses(direct = false)
   6      classes = []
   7      if direct
   8        ObjectSpace.each_object(Class) do |c|
   9          next unless c.superclass == self
  10          classes << c
  11        end
  12      else
  13        ObjectSpace.each_object(Class) do |c|
  14          next unless c.ancestors.include?(self) and (c != self)
  15          classes << c
  16        end
  17      end
  18      classes
  19    end
  20  end
  21  
  22  class TrackSubclassesTest < Test::Unit::TestCase
  23  
  24    class A; end
  25    class B < A; end
  26    class C < B; end
  27    class D < A; end
  28    class E; end
  29    class F < E; end
  30    
  31    def test_subclasses
  32      assert_equal [F], E.subclasses
  33      assert_equal [C], B.subclasses
  34      assert_equal [B, D], A.subclasses(true).sort_by { |c| c.name }
  35      assert_equal [B, C, D], A.subclasses.sort_by { |c| c.name }
  36    end
  37    
  38  end