1 files changed, 7 insertions, 0 deletions
diff --git a/spec/ruby/library/set/proper_superset_spec.rb b/spec/ruby/library/set/proper_superset_spec.rb
index cdfd44f32f..abc0e44f96 100644
--- a/spec/ruby/library/set/proper_superset_spec.rb
+++ b/spec/ruby/library/set/proper_superset_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/set_like'
 require 'set'
 
 describe "Set#proper_superset?" do
@@ -31,4 +32,10 @@ describe "Set#proper_superset?" do
     lambda { Set[].proper_superset?("test") }.should raise_error(ArgumentError)
     lambda { Set[].proper_superset?(Object.new) }.should raise_error(ArgumentError)
   end
+
+  context "when comparing to a Set-like object" do
+    it "returns true if passed a Set-like object that self is a proper superset of" do
+      Set[1, 2, 3, 4].proper_superset?(SetSpecs::SetLike.new([1, 2, 3])).should be_true
+    end
+  end
 end