Add Class#subclasses

Implements [Feature #18273]

Returns an array containing the receiver's direct subclasses without
singleton classes.

1 files changed, 38 insertions, 0 deletions

diff --git a/test/ruby/test_class.rb b/test/ruby/test_class.rb
index eb448e952a..0ceb36bb1d 100644
--- a/test/ruby/test_class.rb
+++ b/test/ruby/test_class.rb
@@ -770,6 +770,44 @@ class TestClass < Test::Unit::TestCase
     end
   end
 
+  def test_subclasses
+    c = Class.new
+    sc = Class.new(c)
+    ssc = Class.new(sc)
+    [c, sc, ssc].each do |k|
+      k.include Module.new
+      k.new.define_singleton_method(:force_singleton_class){}
+    end
+    assert_equal([sc], c.subclasses)
+    assert_equal([ssc], sc.subclasses)
+    assert_equal([], ssc.subclasses)
+
+    object_subclasses = Object.subclasses
+    assert_include(object_subclasses, c)
+    assert_not_include(object_subclasses, sc)
+    assert_not_include(object_subclasses, ssc)
+    object_subclasses.each do |subclass|
+      assert_equal Object, subclass.superclass, "Expected #{subclass}.superclass to be Object"
+    end
+  end
+
+  def test_subclass_gc
+    c = Class.new
+    100000.times do
+      cc = Class.new(c)
+      100.times { Class.new(cc) }
+    end
+    assert(c.subclasses.size <= 100000)
+  end
+
+  def test_subclass_gc_stress
+    10000.times do
+      c = Class.new
+      100.times { Class.new(c) }
+      assert(c.subclasses.size <= 100)
+    end
+  end
+
   def test_classext_memory_leak
     assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
 code = proc { Class.new }