atk4\data\tests\IteratorTest::testBasicID PHP Method

    public function testBasicID()
    {
        $a = ['invoice' => [['total_net' => 10], ['total_net' => 20], ['total_net' => 15]]];
        $this->setDB($a);
        $db = new Persistence_SQL($this->db->connection);
        $i = (new Model($db, 'invoice'))->addFields(['total_net', 'total_vat']);
        $i->addExpression('total_gross', '[total_net]+[total_vat]');
        $i->setOrder('total_net');
        $i->onlyFields(['total_net']);
        $data = [];
        foreach ($i as $id => $item) {
            $data[$id] = clone $item;
        }
        $this->assertEquals(10, $data[1]['total_net']);
        $this->assertEquals(20, $data[2]['total_net']);
        $this->assertEquals(15, $data[3]['total_net']);
        $this->assertEquals(null, $i['total_net']);
    }