The tests fail for me when run on Node 0.10.3 or 0.10.1, reverting to 0.8.21 makes them pass.
Output was:
oyvind:plates osmestad$ npm test

[email protected] test /Users/osmestad/Code/plates
vows --spec test/api-test.js

♢ merge data into markup

✗ Errored » 1 errored

npm ERR! Test failed. See above for more details.
npm ERR! not ok code 0