1 files changed, 17 insertions, 0 deletions
diff --git a/spec/ruby/core/binding/dup_spec.rb b/spec/ruby/core/binding/dup_spec.rb
index 55fac6e333..4eff66bd9a 100644
--- a/spec/ruby/core/binding/dup_spec.rb
+++ b/spec/ruby/core/binding/dup_spec.rb
@@ -10,4 +10,21 @@ describe "Binding#dup" do
     bind.frozen?.should == true
     bind.dup.frozen?.should == false
   end
+
+  it "retains original binding variables but the list is distinct" do
+    bind1 = binding
+    eval "a = 1", bind1
+
+    bind2 = bind1.dup
+    eval("a = 2", bind2)
+    eval("a", bind1).should == 2
+    eval("a", bind2).should == 2
+
+    eval("b = 2", bind2)
+    -> { eval("b", bind1) }.should raise_error(NameError)
+    eval("b", bind2).should == 2
+
+    bind1.local_variables.sort.should == [:a, :bind1, :bind2]
+    bind2.local_variables.sort.should == [:a, :b, :bind1, :bind2]
+  end
 end