From: Phlip <phlip2005@...>
Date: 2008-08-03T01:33:54+09:00
Subject: Re: unit testing advice

Shadowfirebird wrote:
> I certainly "get" the idea that it's better to write the tests first.
> Unfortunately my dinosaur brain needed to write some code to prove
> that my class model was workable...!
> 
> What I'm seeing quite clearly now, is that the next best thing is
> writing the tests while *pretending* that you haven't written the code
> yet.

Right: It's like a little conversation between the tests and code, line by line.

> I suppose you are all going to say that the tests should show what the
> code is supposed to do?  I really like that idea...

The absolute ideal situation:

  - write a little test (maybe add one line to an existing test case)
  - run the test, and its diagnostic tells you what to do next
  - do it
  - run the test and pass it
  - integrate!
  - write a little bit more test
  - it fails, and tells you what to do next
  - do it
  - the test fails again, telling you the _next_ thing to do!
  - do it
  - the tests pass
  - integrate!

The best way to do TDD is make the tests tell you each thing to do next.

But if you can't _easily_ get back to a green-bar, you should revert back to the 
last integration. You should always be able to predict the result of the next 
test run.

-- 
   Phlip