1 files changed, 65 insertions, 0 deletions
diff --git a/spec/ruby/core/enumerable/uniq_spec.rb b/spec/ruby/core/enumerable/uniq_spec.rb
index 0ede0170ce..5ca7556aed 100644
--- a/spec/ruby/core/enumerable/uniq_spec.rb
+++ b/spec/ruby/core/enumerable/uniq_spec.rb
@@ -7,6 +7,71 @@ ruby_version_is '2.4' do
       [0, 1, 2, 3].to_enum.uniq { |n| n.even? }.should == [0, 1]
     end
 
+    it "uses eql? semantics" do
+      [1.0, 1].to_enum.uniq.should == [1.0, 1]
+    end
+
+    it "compares elements first with hash" do
+      x = mock('0')
+      x.should_receive(:hash).at_least(1).and_return(0)
+      y = mock('0')
+      y.should_receive(:hash).at_least(1).and_return(0)
+
+      [x, y].to_enum.uniq.should == [x, y]
+    end
+
+    it "does not compare elements with different hash codes via eql?" do
+      x = mock('0')
+      x.should_not_receive(:eql?)
+      y = mock('1')
+      y.should_not_receive(:eql?)
+
+      x.should_receive(:hash).at_least(1).and_return(0)
+      y.should_receive(:hash).at_least(1).and_return(1)
+
+      [x, y].to_enum.uniq.should == [x, y]
+    end
+
+    it "compares elements with matching hash codes with #eql?" do
+      a = Array.new(2) do
+        obj = mock('0')
+        obj.should_receive(:hash).at_least(1).and_return(0)
+
+        def obj.eql?(o)
+          # It's undefined whether the impl does a[0].eql?(a[1]) or
+          # a[1].eql?(a[0]) so we taint both.
+          taint
+          o.taint
+          false
+        end
+
+        obj
+      end
+
+      a.uniq.should == a
+      a[0].tainted?.should == true
+      a[1].tainted?.should == true
+
+      a = Array.new(2) do
+        obj = mock('0')
+        obj.should_receive(:hash).at_least(1).and_return(0)
+
+        def obj.eql?(o)
+          # It's undefined whether the impl does a[0].eql?(a[1]) or
+          # a[1].eql?(a[0]) so we taint both.
+          taint
+          o.taint
+          true
+        end
+
+        obj
+      end
+
+      a.to_enum.uniq.size.should == 1
+      a[0].tainted?.should == true
+      a[1].tainted?.should == true
+    end
+
     context 'when yielded with multiple arguments' do
       before :each do
         @enum = Object.new.to_enum