What do you need for better application testing?

Since we're in the middle of rewriting CI for version 4, and obviously testing the code as we go along, I got to wondering what everyone is expecting to make testing their applications easier.

I've seen it brought up on the forums before, but it seems like the big thing that I always heard was "Mocked system classes". I guess I'm not thinking clearly on this because you can already Mock classes with phpUnit:

Code:

$stub = $this->getMockBuilder('SomeClass')
                     ->getMock();

So, what would everyone need to be able to cleanly test their applications. (Other than someone to write all of the tests for them....)

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