test_object.rb: add assertions
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47525 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_object.rb: add assertions
[Feature #8923].
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47525 b2dd03c8-39d4-4d8f-98ff-823fe69b080e