1 files changed, 15 insertions, 0 deletions
diff --git a/spec/ruby/core/hash/rehash_spec.rb b/spec/ruby/core/hash/rehash_spec.rb
index 5b15af923a..f44b42eecf 100644
--- a/spec/ruby/core/hash/rehash_spec.rb
+++ b/spec/ruby/core/hash/rehash_spec.rb
@@ -35,6 +35,21 @@ describe "Hash#rehash" do
     h[k2].should == v2
   end
 
+  it "removes duplicate keys" do
+    a = [1,2]
+    b = [1]
+
+    h = {}
+    h[a] = true
+    h[b] = true
+    b << 2
+    h.size.should == 2
+    h.keys.should == [a, b]
+    h.rehash
+    h.size.should == 1
+    h.keys.should == [a]
+  end
+
   it "raises a #{frozen_error_class} if called on a frozen instance" do
     lambda { HashSpecs.frozen_hash.rehash  }.should raise_error(frozen_error_class)
     lambda { HashSpecs.empty_frozen_hash.rehash }.should raise_error(frozen_error_class)