Merge pull request #1 from Yujun-Qian/master

add unit tests
YuJun is the author
bring statement coverage to 91.87%
add validates ok case
rm unneeded --
Merge pull request #2 from isao/tests

bring statement coverage to 93.5%
Merge pull request #4 from isao/author

update author in package.json
Merge pull request #1 from yahoo/master

sync with upstream