Add spec for eval("")

Author: eregon

spec/ruby/core/kernel/eval_spec.rb

@@ -270,6 +270,10 @@ class EvalSpecs
     ScratchPad.clear
   end
 
+  it "returns nil if given an empty string" do
+    eval("").should == nil
+  end
+
   # See language/magic_comment_spec.rb for more magic comments specs
   describe "with a magic encoding comment" do
     it "uses the magic comment encoding for the encoding of literal strings" do