Its possible (although you'll probably need some external tool, like Flex).
However TDD (and unit tests in general) have this issue of that if you want to do it properly, the testing code becoming larger than the code it tests. Also there is the extra issue of writing tests which subconsciously avoid some of the edgy parts. To avoid this you need to split the coders in those who will write the tested code and those who will test the code based on the public API.
Given that unit testing usually makes sense in teams of programmers (especially large-ish teams) and that to make it properly and with so-called blackbox testing (the above method i mentioned) to avoid the case of writing code that avoids the edgy parts you need even more people, its probably not very useful in the realm if indieness :-).
Also personally i don't see the point in writing so many tests for games at all. Its not banking software.
Now i'm sure somebody out there does this, but i'm also sure that the majority of (indie and not) games developers do not and the gain isn't that big for games.