Add in-tree mspec and ruby/spec

* For easier modifications of ruby/spec by MRI developers.
* .gitignore: track changes under spec.
* spec/mspec, spec/rubyspec: add in-tree mspec and ruby/spec.
  These files can therefore be updated like any other file in MRI.
  Instructions are provided in spec/README.
  [Feature #13156] [ruby-core:79246]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58595 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/rubyspec/core/class/inherited_spec.rb

@@ -0,0 +1,102 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Class.inherited" do
+
+  before :each do
+    ScratchPad.record nil
+  end
+
+  it "is invoked with the child Class when self is subclassed" do
+    begin
+      top = Class.new do
+        def self.inherited(cls)
+          $child_class = cls
+        end
+      end
+
+      child = Class.new(top)
+      $child_class.should == child
+
+      other_child = Class.new(top)
+      $child_class.should == other_child
+    ensure
+      $child_class = nil
+    end
+  end
+
+  it "is invoked only once per subclass" do
+    expected = [
+      [CoreClassSpecs::Inherited::A, CoreClassSpecs::Inherited::B],
+      [CoreClassSpecs::Inherited::B, CoreClassSpecs::Inherited::C],
+    ]
+
+    CoreClassSpecs::Inherited::A::SUBCLASSES.should == expected
+  end
+
+  it "is called when marked as a private class method" do
+    a = Class.new do
+      def self.inherited(klass)
+        ScratchPad.record klass
+      end
+    end
+    a.private_class_method :inherited
+    ScratchPad.recorded.should == nil
+    b = Class.new(a)
+    ScratchPad.recorded.should == b
+  end
+
+  it "is called when marked as a protected class method" do
+    a = Class.new
+    class << a
+      def inherited(klass)
+        ScratchPad.record klass
+      end
+      protected :inherited
+    end
+    ScratchPad.recorded.should == nil
+    b = Class.new(a)
+    ScratchPad.recorded.should == b
+  end
+
+  it "is called when marked as a public class method" do
+    a = Class.new do
+      def self.inherited(klass)
+        ScratchPad.record klass
+      end
+    end
+    a.public_class_method :inherited
+    ScratchPad.recorded.should == nil
+    b = Class.new(a)
+    ScratchPad.recorded.should == b
+  end
+
+  it "is called by super from a method provided by an included module" do
+    ScratchPad.recorded.should == nil
+    e = Class.new(CoreClassSpecs::F)
+    ScratchPad.recorded.should == e
+  end
+
+  it "is called by super even when marked as a private class method" do
+    ScratchPad.recorded.should == nil
+    CoreClassSpecs::H.private_class_method :inherited
+    i = Class.new(CoreClassSpecs::H)
+    ScratchPad.recorded.should == i
+  end
+
+  it "will be invoked by child class regardless of visibility" do
+    top = Class.new do
+      class << self
+        def inherited(cls); end
+      end
+    end
+
+    class << top; private :inherited; end
+    lambda { Class.new(top) }.should_not raise_error
+
+    class << top; protected :inherited; end
+    lambda { Class.new(top) }.should_not raise_error
+  end
+
+end
+