1 files changed, 26 insertions, 0 deletions
diff --git a/spec/ruby/core/rational/to_r_spec.rb b/spec/ruby/core/rational/to_r_spec.rb
new file mode 100644
index 0000000000..eb6097f595
--- /dev/null
+++ b/spec/ruby/core/rational/to_r_spec.rb
@@ -0,0 +1,26 @@
+require_relative "../../spec_helper"
+
+describe "Rational#to_r" do
+  it "returns self" do
+    a = Rational(3, 4)
+    a.to_r.should.equal?(a)
+
+    a = Rational(bignum_value, 4)
+    a.to_r.should.equal?(a)
+  end
+
+  it "raises TypeError trying to convert BasicObject" do
+    obj = BasicObject.new
+    -> { Rational(obj) }.should.raise(TypeError)
+  end
+
+  it "works when a BasicObject has to_r" do
+    obj = BasicObject.new; def obj.to_r; 1 / 2.to_r end
+    Rational(obj).should == Rational('1/2')
+  end
+
+  it "fails when a BasicObject's to_r does not return a Rational" do
+    obj = BasicObject.new; def obj.to_r; 1 end
+    -> { Rational(obj) }.should.raise(TypeError)
+  end
+end