1 files changed, 69 insertions, 0 deletions
diff --git a/spec/ruby/core/class/dup_spec.rb b/spec/ruby/core/class/dup_spec.rb
new file mode 100644
index 0000000000..17c0171ceb
--- /dev/null
+++ b/spec/ruby/core/class/dup_spec.rb
@@ -0,0 +1,69 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+# NOTE: This is actually implemented by Module#initialize_copy
+describe "Class#dup" do
+  it "duplicates both the class and the singleton class" do
+    klass = Class.new do
+      def hello
+        "hello"
+      end
+
+      def self.message
+        "text"
+      end
+    end
+
+    klass_dup = klass.dup
+
+    klass_dup.new.hello.should == "hello"
+    klass_dup.message.should == "text"
+  end
+
+  it "retains an included module in the ancestor chain for the singleton class" do
+    klass = Class.new
+    mod = Module.new do
+      def hello
+        "hello"
+      end
+    end
+
+    klass.extend(mod)
+    klass_dup = klass.dup
+    klass_dup.hello.should == "hello"
+  end
+
+  it "retains the correct ancestor chain for the singleton class" do
+    super_klass = Class.new do
+      def hello
+        "hello"
+      end
+
+      def self.message
+        "text"
+      end
+    end
+
+    klass = Class.new(super_klass)
+    klass_dup = klass.dup
+
+    klass_dup.new.hello.should == "hello"
+    klass_dup.message.should == "text"
+  end
+
+  it "sets the name from the class to nil if not assigned to a constant" do
+    copy = CoreClassSpecs::Record.dup
+    copy.name.should == nil
+  end
+
+  it "stores the new name if assigned to a constant" do
+    CoreClassSpecs::RecordCopy = CoreClassSpecs::Record.dup
+    CoreClassSpecs::RecordCopy.name.should == "CoreClassSpecs::RecordCopy"
+  ensure
+    CoreClassSpecs.send(:remove_const, :RecordCopy)
+  end
+
+  it "raises TypeError if called on BasicObject" do
+    -> { BasicObject.dup }.should.raise(TypeError, "can't copy the root class")
+  end
+end