public function testCollectionReturnsUniqueItems()
{
$e1 = new Entity();
$e1->id = 1;
$e2 = new Entity();
$e2->id = 2;
$c = new Collection(array($e1, $e2, $e2));
$this->assertEquals(new Collection(array($e1, $e2)), $c->unique());
}
