Tests `Collection::assignTo`.

Source

						public function testAssignTo() {
		$parent = new stdClass;
		$config = array('valid' => false, 'model' => $this->_model);
		$collection = new DocumentSet;
		$collection->assignTo($parent, $config);
		$this->assertEqual($this->_model, $collection->model());
		$this->assertEqual($parent, $collection->parent());
	}