[TIP] Functional Testing of Desktop Applications

[Laura Creighton]

In a message of Mon, 05 Mar 2007 00:01:35 GMT, Michael Foord writes:
<snip>
>This leads us into a bit of a debate about how much to mock out in our 
>unit tests. The most extreme testing doctrine says that you should mock 
>out *all* your dependencies when testing a unit - even dependencies 
>within the same object (if you are testing method 'a' and it contains a 
>call to function or method 'b' you should mock 'b').
>
>When you have a short function that has several dependencies this can 
>make writing the tests a real chore. It *also* means that you don't 
>catch errors at a higher level - where you mock you test adequately what 
>you *think* the wiring between your units is doing, but your mental 
>model may be just as buggy as your code.

A different, related problem.  The idea is that your tests stay live
and you run them all periodically to make sure nothing breaks.  Do
this properly, and write a thing like pypy (and py.test) and you
will find that a run of all your tests takes 3-4 hours. :-(  Thus
the most extreme doctrine above only works on "small-enough" projects.

Deciding what to do when your project is no longer "small enough" is
hard.

Laura Creighton