The green red hi-lighting on individual test successes and failure, and on the summary bar that tells you whether all the tests passed, is a very important visual clue.

I guess it got stripped out of the base theme, when someone went through trying to make it as plane as possible, and then no-one has put it back into any of the real themes.

I think that this is sufficiently fundamental (and also, only developer focussed) that these colours should go back into the base theme. At the very least they should be put into canvas, and similar parent themes.