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diff --git a/spec/rubyspec/shared/rational/round.rb b/spec/rubyspec/shared/rational/round.rb
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+++ b/spec/rubyspec/shared/rational/round.rb
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+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe :rational_round, shared: true do
+  before do
+    @rational = Rational(2200, 7)
+  end
+
+  describe "with no arguments (precision = 0)" do
+    it "returns an integer" do
+      @rational.round.should be_kind_of(Integer)
+      Rational(0, 1).round(0).should be_kind_of(Integer)
+      Rational(124, 1).round(0).should be_kind_of(Integer)
+    end
+
+    it "returns the truncated value toward the nearest integer" do
+      @rational.round.should == 314
+      Rational(0, 1).round(0).should == 0
+      Rational(2, 1).round(0).should == 2
+    end
+
+    it "returns the rounded value toward the nearest integer" do
+      Rational(1, 2).round.should == 1
+      Rational(-1, 2).round.should == -1
+      Rational(3, 2).round.should == 2
+      Rational(-3, 2).round.should == -2
+      Rational(5, 2).round.should == 3
+      Rational(-5, 2).round.should == -3
+    end
+  end
+
+  describe "with a precision < 0" do
+    it "returns an integer" do
+      @rational.round(-2).should be_kind_of(Integer)
+      @rational.round(-1).should be_kind_of(Integer)
+      Rational(0, 1).round(-1).should be_kind_of(Integer)
+      Rational(2, 1).round(-1).should be_kind_of(Integer)
+    end
+
+    it "moves the truncation point n decimal places left" do
+      @rational.round(-3).should == 0
+      @rational.round(-2).should == 300
+      @rational.round(-1).should == 310
+    end
+  end
+
+  describe "with a precision > 0" do
+    it "returns a Rational" do
+      @rational.round(1).should be_kind_of(Rational)
+      @rational.round(2).should be_kind_of(Rational)
+      Rational(0, 1).round(1).should be_kind_of(Rational)
+      Rational(2, 1).round(1).should be_kind_of(Rational)
+    end
+
+    it "moves the truncation point n decimal places right" do
+      @rational.round(1).should == Rational(3143, 10)
+      @rational.round(2).should == Rational(31429, 100)
+      @rational.round(3).should == Rational(157143, 500)
+      Rational(0, 1).round(1).should == Rational(0, 1)
+      Rational(2, 1).round(1).should == Rational(2, 1)
+    end
+
+    it "doesn't alter the value if the precision is too great" do
+      Rational(3, 2).round(10).should == Rational(3, 2).round(20)
+    end
+
+    # #6605
+    it "doesn't fail when rounding to an absurdly large positive precision" do
+      Rational(3, 2).round(2_097_171).should == Rational(3, 2)
+    end
+  end
+end