I took the liberty of rewriting the webtests : I tried to run them, and they were completely outdated. I guess they are never ran... Not that they are completely exhaustive, but the mock tests are not either (eg they don't test the tag lib). Wasn't completely useless : I even found/fixed a bug in the process...
For the record, the webtests were using Canoo Webtest, a browser-less framework that had its time but is now pretty much deprecated. Therefore I have re-written the tests using Selenium + Findr (a small utility for writing better Selenium tests, easier).
The tests basically check that the Calc sample works (both old-skool and ajax versions), and tries a few things over bugzooky.
One can run the tests via the IDE (they're basic junit tests), and via maven
mvn clean install -Pwebtests
This should run the example app inside a jetty instance, exec all tests using Firefox, and shutdown the app server.
For those who prefer chrome - which is way faster (you'll need chromedriver installed locally) :