About the usage of tinytest, you may want to take a look at those useful ressources:
The basics are explained in this screencast:
https://www.eventedmind.com/feed/meteor-testing-packages-with-tinytest
Once you understood the idea, you'll want the public API documentation for tinytest. For now, the only documentation for that is at the end of the source of the tinytest package: https://github.com/meteor/meteor/tree/devel/packages/tinytest
Also, the screencast talks about test-helpers, you may want to have a look at all the available helpers in here:
https://github.com/meteor/meteor/tree/devel/packages/test-helpers
There often is some documentation inside each file
Digging in the existing tests of meteor's packages will provide a lot of examples. One way of doing this is to make a search for Tinytest. or test. in the package directory of meteor's source code
