moves Class#reachable? to Module#reachable?, bases implementation on...

moves Class#reachable? to Module#reachable?, bases implementation on anonymous? and constantize, and adds test coverage

activesupport/lib/active_support/core_ext/class/subclasses.rb

-require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/module/anonymous'
+require 'active_support/core_ext/module/reachable'
 
 class Class #:nodoc:
   # Returns an array with the names of the subclasses of +self+ as strings.
@@ -8,10 +9,6 @@ def subclasses
     Class.subclasses_of(self).map { |o| o.to_s }
   end
 
-  def reachable? #:nodoc:
-    eval("defined?(::#{self}) && ::#{self}.equal?(self)")
-  end
-
   # Rubinius
   if defined?(Class.__subclasses__)
     def descendents
@@ -51,7 +48,7 @@ def descendents
   def self.subclasses_of(*superclasses) #:nodoc:
     subclasses = []
     superclasses.each do |klass|
-      subclasses.concat klass.descendents.select {|k| k.name.blank? || k.reachable?}
+      subclasses.concat klass.descendents.select {|k| k.anonymous? || k.reachable?}
     end
     subclasses
   end

activesupport/lib/active_support/core_ext/module.rb

 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/module/introspection'
 require 'active_support/core_ext/module/anonymous'
+require 'active_support/core_ext/module/reachable'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/module/attr_internal'
 require 'active_support/core_ext/module/attr_accessor_with_default'

activesupport/lib/active_support/core_ext/module/reachable.rb

+require 'active_support/core_ext/module/anonymous'
+require 'active_support/core_ext/string/inflections'
+
+class Module
+  def reachable? #:nodoc:
+    !anonymous? && name.constantize.equal?(self)
+  rescue NameError
+    false
+  end
+end

activesupport/test/core_ext/module/reachable_test.rb

+require 'abstract_unit'
+require 'active_support/core_ext/module/reachable'
+
+class AnonymousTest < ActiveSupport::TestCase
+  test "an anonymous class or module is not reachable" do
+    assert !Module.new.reachable?
+    assert !Class.new.reachable?
+  end
+  
+  test "ordinary named classes or modules are reachable" do
+    assert Kernel.reachable?
+    assert Object.reachable?
+  end
+  
+  test "a named class or module whose constant has gone is not reachable" do
+    c = eval "class C; end; C"
+    m = eval "module M; end; M"
+    
+    self.class.send(:remove_const, :C)
+    self.class.send(:remove_const, :M)
+    
+    assert !c.reachable?
+    assert !m.reachable?
+  end
+  
+  test "a named class or module whose constants store different objects are not reachable" do
+    c = eval "class C; end; C"
+    m = eval "module M; end; M"
+    
+    self.class.send(:remove_const, :C)
+    self.class.send(:remove_const, :M)    
+
+    eval "class C; end"
+    eval "module M; end"
+    
+    assert C.reachable?
+    assert M.reachable?
+    assert !c.reachable?
+    assert !m.reachable?
+  end
+end
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