assertIsSubset

Hi chaps,
I've just forked phpunit and added new assert for checking if a
$expected value is a subset of $actual.
Works with objects and arrays.

Make sense if you want to test you code but don't want to write 10
lines of assertEquals for individual fields.

example usage
{{{
$expected = array(
 'id' => 7,
 'nodes' => array(
  array('id' => 3),
  array('id' => 12),
 )
);
$actual = $myAPI->myCall();

$this->assertIsSubset($expected, $actual);
}}}

Whole idea is that your API might change over time (new fields in
response, ...) but this particular test doesn't care about whole
response. It's just checking if $actual variable meets the minimum
requirements.

What do you think? Can you see it useful?
I would love to hear some feedback.

Cheers,
W
--
Wojtek Oledzki
hoborglabs.com