Sokil\Mongo\DocumentRelationTest::testAddRelation_ManyMany PHP Method

    public function testAddRelation_ManyMany()
    {
        $carsCollection = $this->database->getCollection('cars');
        $driversCollection = $this->database->getCollection('drivers');
        $driver1 = $driversCollection->createDocument(array('name' => 'Dmytro'))->save();
        $driver2 = $driversCollection->createDocument(array('name' => 'Natalia'))->save();
        $car1 = $carsCollection->createDocument(array('number' => 'AA0123AK'))->save();
        $car2 = $carsCollection->createDocument(array('number' => 'AA4567AK'))->save();
        $car1->addRelation('drivers', $driver1);
        $driver2->addRelation('cars', $car1);
        $car2->addRelation('drivers', $driver1);
        $driver2->addRelation('cars', $car2);
        // check emdedded relation fields
        $this->assertEquals(array($driver1->getId(), $driver2->getId()), array_keys($car1->getRelated('drivers')));
        $this->assertEquals(array($driver1->getId(), $driver2->getId()), array_keys($car2->getRelated('drivers')));
    }