public function testFilter()
{
$col = new MessageCollection();
$col->add($m = new Message('a'));
$col->add(new Message('b'));
$col->add(new Message('c'));
$col->filter(function ($v) {
return 'a' === $v->getId();
});
$this->assertEquals(array('a'), array_keys($col->all()));
$this->assertSame($m, $col->get('a'));
}
