From: Jim Weirich <jweirich@...>
Date: 2003-06-03T10:30:00+09:00
Subject: Re: Unit Testing Style

On Mon, 2003-06-02 at 16:08, Eric Schwartz wrote:
> I know I should have written my tests first, but I didn't, so now I'm
> trying to do them after the fact.  I'm running into a few style
> questions, though, not being used to the Test::Unit style of testing:
> 
> 1) I have several test cases that do multiple assert_* calls.  Is that
>    a Good Thing, a Bad Thing, or not something that's even worth
>    worrying about?  Usually it's things like "Was the file created?
>    Does it contain data of the right format?  Is the data correct?"

Just remember that the test method will terminate with the first failing
assert_*.  So if you have a lot of them in a single method, you could
have multiple failures hiding behind a single failure.

>    In one case, however, the test case is "run a command remotely that
>    logs to yet another remote database, and verify the command was
>    run, output was generated, logged to the right database with the
>    right timestamp, from the right machine, etc., etc., etc."

I try to keep the external environment as simple and self contained as
possible.  I want to run the unit tests and KNOW everything is ok.  If
my tests depend on a lot of external resources, then failure may mean a
problem with the code or a problem with the environment.  I would rather
spend time working on the code than tracing down environment problems.

Sometimes you DO need to talk to external resources (e.g. databases,
servers, etc.).  I usually isolate these tests in their own area
(usually a separate Rake/Make target).  Then I can run the unit tests to
check the code as often as I want and get a lots of "feel good" karma. 
And then I can run the environment dependent tests separately to make
sure I still can talk to the outside world.

> 2) How do people generally feel about interactivity in test cases?  

Evil!  Don't do this!  Never (at least in unit tests).

If you REALLY need some interactivity, I would move it outside the unit
tests.

> Other than that, I'm enjoying Test::Unit quite a lot.

Great!

-- 
-- Jim Weirich     jweirich@one.net    http://jimweirich.umlcoop.net
---------------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct, 
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)