We have a rudimentary unit test framework [1] that we've been using for the samples, though we're still playing with different styles. Personally, I'm fond of the Jasmine-inspired stuff I tried to slap together here [2]. This is of course different from the testing infrastructure for the language itself, which is its own thing.

    [1] https://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/#dart%2Fclient%2Ftesting%2Funittest
    [2] https://code.google.com/p/dart/source/browse/branches/bleeding_edge/dart/client/tests/client/view/ViewTests.dart