Reinstate Object.subclasses_of and Class#descendents for plugin compat.

This reverts commits 7d312e54bad9c39634c137caec07dfc8df471650, 5f981ff0294ba45aa44ad15aa063970b29aeec44, f85f5dfc8ffefff174b695c6363211d342f77a57, 245bfafe335ff883f7a096eab95ac22fe2848679, and ec7c642f5fe60afc857aa64f1a9b4c2be56f9d70

1 files changed, 29 insertions, 0 deletions

diff --git a/activesupport/test/core_ext/class_test.rb b/activesupport/test/core_ext/class_test.rb
new file mode 100644
index 0000000000..b7f3dd9930
--- /dev/null
+++ b/activesupport/test/core_ext/class_test.rb
@@ -0,0 +1,29 @@
+require 'abstract_unit'
+require 'active_support/core_ext/class'
+
+class A
+end
+
+module X
+  class B
+  end
+end
+
+module Y
+  module Z
+    class C
+    end
+  end
+end
+
+class ClassTest < Test::Unit::TestCase
+  def test_retrieving_subclasses
+    @parent   = eval("class D; end; D")
+    @sub      = eval("class E < D; end; E")
+    @subofsub = eval("class F < E; end; F")
+    assert_equal 2, @parent.subclasses.size
+    assert_equal [@subofsub.to_s], @sub.subclasses
+    assert_equal [], @subofsub.subclasses
+    assert_equal [@sub.to_s, @subofsub.to_s].sort, @parent.subclasses.sort
+  end
+end