For my PDX.pm presentation tonight on Test::Builder2 I threw together some quick examples of some of its killer features, in particular demonstrating changing how Test::Builder2 behaves using method modifiers and applying object roles.
First, demonstrating end-of-assert actions, there's die on fail but even cooler is DEBUG on fail! That's right, run your test in the debugger and have it automatically set a breakpoint on a failure. How cool is that?
I'm sure somebody with better debugger foo than I can make it even cooler and stop at the top of the assert stack rather than inside DebugOnFail.
The second is reimplementing Test::NoWarnings safely. TB2::NoWarnings demonstrates hooking into the start and end of the test as well as safely altering the number of tests planned by trapping the call to set_plan.
You can safely use them all together, though its a crap shoot if DebugOnFail or DieOnFail will trigger first.
While roles and method modifiers are relatively new to the Perl community, using them in lieu of designing my own event system for TB2 has two great advantages. First, I didn't have to design and debug my own event system.
There's a pile of stuff to be done in TB2, a lot of them are fairly small and self contained. Have a look. Patches welcome.