From: Stefan Schmiedl <s@...>
Date: 2001-12-08T18:48:42+09:00
Subject: [ruby-talk:27911] Re: A challenge to proponents of Unit Testing.

rmoldskr@online.no (2001-12-08 18:16):
> 
> But doesn't the assumption that the cases are independant break the
> black box? How do you know that it's enough to check the three cases
> where just one of the sides have illegal values without knowing or
> making assumptions about the implementation?

well, not even Marvin's brain the size of a planet won't be able
to test *all* possible combinations of numbers. you just draw a line
somewhere.

there is a change of terminology in process over in xp-land.
replace unit tests with programmer tests and acceptance test
with customer test.

so unit tests are written by the programmers who know what they
implement.

> 
> But doesn't focusing on testing the specification mean that you might
> overlook vagueness in the specification and with that undefined
> behaviour in the product?

but by writing tests for the specs you often discover the vagueness
before writing something you thought the customer implied but did not.

> 
> If nobody realizes that the specification doesn't cover a value that
> might arise in a real deployment, then you're not going to discover
> that as you are always only testing the by the specification. Or am I
> misunderstanding something?

yes. you are allowed to apply common sense :-)
test first shows its full power when applied together with all of
the other xp practices. you just don't sit in a cubicle with a spec
binder and translate the words into a test suite all by yourself.
you have a whole network of fellow programmers and a customer at
hand who you can ask, if a problem arises. Basically, you are not
left alone.

s.
-- 
Stefan Schmiedl
EDV-Beratung, Programmierung, Schulung
Loreleystr. 5, 94315 Straubing, Germany
Tel. (0 94 21) 74 01 06
Public Key: http://xss.de/stefan.public

shhhh ... I can't hear my code!