use Perl

I recently did a ten-minute talk on Test-First of OO modules. This got me to thinking 'hey, I should put this on my blog' ... which got me to thinking 'hey, I should have a blog. If it were RSS enabled, Steve Hoek could use it to test his RSS Reader ...' :-)

So, here it is:

Let's say we're going to create a module called 'SomeObject'.

We knoew SomeObject will be a container, and it will take three optional paramaters on creation: The values of the entries at A, B, and C.

SomeObject will have two methods, 'Get' and 'Set'

So, we design the following tests:

1) Does SomeObject.pm compile?
2) Does SomeObject have new and get methods?
3) If I new, does it create a SomeObject object?
4,5,6) With the Object I created above, does it have the correct values for A, B, C?
7) Is the entry for D "Undefined?"

The tests are below:

#---------BEGIN CODE---------#
#use lib wherever SomeObject is. ('./')?
use Test::More;
BEGIN { plan tests => 7 };
use_ok('SomeObject');

can_ok('SomeObject', qw(new get) );

my $t = SomeObject->new(1,2,3);
isa_ok($t, 'SomeObject');

my $a = $t->get('A');
ok($a, 1, "Get 1st Parameter");

my $b = $t->get('B');
ok($b, 2, "Get 2nd Parameter");

my $c = $t->get('C');
ok($c, 3, "Get 3rd Parameter");

my $d = $t->get('D');
my $blnOk = 0;
if (!defined($d)) { $blnOk=1;}
ok($blnOk==1, "Making sure no extra variables are created");
# --- If we really wanted to be slick, I'd
# iterate from D to ZZZ or so, but I don't
# The for would have a bln we'd check, so we'd
# only have one variable, not 26*26*26.
#
#---------END CODE---------#

When you run the test file intially, only the use should pass, because you haven't even _coded_ the other methods.

Then, you code and test. Eventually, the test results look like this:

1..7
ok 1 - use PH::SomeObject;
ok 2 - PH::SomeObject->can(...)
ok 3 - The object isa PH::SomeObject
ok 4 - Get 1st Parameter
ok 5 - Get 2nd Parameter
ok 6 - Get 3rd Parameter
ok 7 - Making sure no extra variables are created

Pretty nifty eh?

Not really, but it's a good start.