public function testBelongsToRelationForeignKeyIsSaved()
 {
     $owner = new User();
     $owner->name = 'Mickey Mouse';
     $owner->save();
     $car = new Car();
     $car->color = 'red';
     $car->fuel = 'unleaded';
     $car->cruft = 'red is my favorite';
     $car->owner()->associate($owner);
     $car->save();
     $dbCar = DB::table('vehicles')->first();
     $this->assertEquals($car->id, $dbCar->id);
     $this->assertEquals($owner->id, $dbCar->owner_id);
 }