Flesh out Kernel#remove_instance_variable spec

spec/ruby/core/kernel/fixtures/classes.rb

@@ -295,6 +295,12 @@ def method_missing(method, *args)
       "Done #{method}(#{args})"
     end
   end
+
+  class Ivar
+    def initialize
+      @greeting = "hello"
+    end
+  end
 end
 
 class EvalSpecs

spec/ruby/core/kernel/remove_instance_variable_spec.rb

@@ -5,4 +5,34 @@
   it "is a private method" do
     Kernel.should have_private_instance_method(:remove_instance_variable)
   end
+
+  it "removes an ivar of a given name and return it's value" do
+    val = KernelSpecs::Ivar.new.send :remove_instance_variable, :@greeting
+    val.should == "hello"
+  end
+
+  it "supports the name being a string" do
+    val = KernelSpecs::Ivar.new.send :remove_instance_variable, "@greeting"
+    val.should == "hello"
+  end
+
+  it "tries to call #to_str if it's not a String or Symbol" do
+    s = mock("str")
+    s.should_receive(:to_str).and_return("@greeting")
+
+    val = KernelSpecs::Ivar.new.send :remove_instance_variable, s
+    val.should == "hello"
+  end
+
+  it "raises NameError if the ivar isn't defined" do
+    lambda {
+      KernelSpecs::Ivar.new.send :remove_instance_variable, :@unknown
+    }.should raise_error(NameError)
+  end
+
+  it "rejects unknown argument types" do
+    lambda {
+      KernelSpecs::Ivar.new.send :remove_instance_variable, Object
+    }.should raise_error(TypeError)
+  end
 end