[TIP] Interface vs Implementation Testing

[Titus Brown]

On Mon, Apr 23, 2007 at 02:58:57PM -0500, Kumar McMillan wrote:
-> On 4/21/07, Titus Brown <titus at caltech.edu> wrote:
-> >-> kinda know things still work.  You see where I'm going with that.  I
-> >-> tell developers on my team to **only** test interfaces and **never**
-> >-> test implementation and will slap wrists if I have to :)
-> >
-> >*boggle*
-> >
-> >Why not delete failing tests when the code they're testing no longer
-> >exists, and replace them with the tests that you wrote for the new code?
-> 
-> I coded a huge test suite once that primarily unit tested
-> implementation.  Since there were many tests, any time I wanted to
-> change the way the app was implemented (faster algorithm here, don't
-> need this class anymore, more methods now because of feature X) I
-> usually ended up spending a good deal of time updating and deleting
-> tests.  This just seemed unecessary to me and deterred me from relying
-> on the test suite as an indication of successful functionality.

So, isn't this kind of an argument for functional and regression tests
only?

(I'm honestly curious.  I haven't found much of a need for unit tests in
my own code.)

--titus