add an assertion.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48452 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_time.rb

@@ -171,6 +171,7 @@ class TestTime < Test::Unit::TestCase
     assert_equal(100000, Time.at(0.0001).nsec)
     assert_equal(10000, Time.at(0.00001).nsec)
     assert_equal(3000, Time.at(0.000003).nsec)
+    assert_equal(200, Time.at(0.0000002r).nsec)
     assert_equal(199, Time.at(0.0000002).nsec)
     assert_equal(10, Time.at(0.00000001).nsec)
     assert_equal(1, Time.at(0.000000001).nsec)