commit 0c7ddce2ce07695f745a08ba04831f7845670d68
Author: Kenta Murata <mrkn@mrkn.jp>
Date:   Mon Jun 13 23:52:52 2016 +0900

    Add assertions for Kernel.Rational

diff --git a/test/ruby/test_rational.rb b/test/ruby/test_rational.rb
index 07d0ae5..68e3285 100644
--- a/test/ruby/test_rational.rb
+++ b/test/ruby/test_rational.rb
@@ -1,10 +1,34 @@
 # frozen_string_literal: false
 require 'test/unit'
+require '-test-/integer'
 
 class RationalSub < Rational; end
 
 class Rational_Test < Test::Unit::TestCase
 
+  def test_new
+    assert_raise(TypeError) { Rational(Object.new) }
+    assert_raise(TypeError) { Rational(1, Object.new) }
+
+    class << (o = Object.new)
+      alias to_int object_id
+    end
+
+    assert_raise(TypeError) { Rational(o) }
+    assert_raise(TypeError) { Rational(1, o) }
+
+    class << (o = Object.new)
+      def to_r
+        1/2r
+      end
+    end
+
+    assert_equal(1/2r, Rational(o))
+    assert_raise(TypeError) { Rational(1, o) }
+
+    Rational(Bug::Integer::MyInteger.new)
+  end
+
   def test_ratsub
     c = RationalSub.__send__(:convert, 1)