I shared your worries about the turnover time for unit tests. But if you use something like [Midje][1] with the 'autotest' feature on, your tests will run in the background after each save. It typically takes a fraction of a second to run the full suite, so by the time I'm done hitting save and switching over to the midje console, the test results are already there.

[1]: https://github.com/marick/Midje