何時在測驗驅動開發(TDD)中驗證類的輸入-有解無憂

我有一個名為MachineId. 創建此類的實體時，我想確保建構式引數已驗證。

class MachineId
{
    
    private $uid;
    
    public function __construct(string $uid)
    {
        $this->uid = $uid;
    }
    
    public function validate() : bool
    {
        // check uid against specific format (by regex) and return true if valid and false if invalid
    }
    
}

我的問題是：我應該什么時候進行驗證？

我應該在創建 MachineId 實體時進行驗證嗎？在這種情況下，將validate方法設為私有是有意義的。這會使使用 Unittest 對其進行測驗變得困難。

// Validation WHILE instantiation
class MachineId
{
    
    private $uid;
    
    public function __construct(string $uid)
    {
        $this->uid = $uid;
        if($this->validate() === false) {
            // throw exception
        }
    }
    
    private function validate() : bool
    {
        ...
    }
    
}

我應該在創建 MachineId 實體之前進行驗證嗎？這將使validate通過 Unittest測驗該方法成為可能，需要在創建物件之前呼叫驗證。使該方法validate成為靜態方法（我試圖阻止）是有意義的。

// Validation BEFORE instantiation
class MachineId
{
    
    private $uid;
    
    public function __construct(string $uid)
    {
        $this->uid = $uid;
    }
    
    public static function validate(string $uid) : bool
    {
        ...
    }
    
}

if(MachineId::validate($uid) === false) {
    // throw exception
};
$machineId = new MachineId($uid);

Should I do the validation after I create an instance of MachineId? This would make it possible to test the validate method by Unittest, requires that validation is called after creating the object.

// Validation AFTER instantiation
class MachineId
{
    
    private $uid;
    
    public function __construct(string $uid)
    {
        $this->uid = $uid;
    }
    
    public function validate() : bool
    {
        ...
    }
    
}

$machineId = new MachineId($uid);
if($machineId->validate() === false) {
    // throw exception
}

Should I create an empty MachineId and then set the uid? In this case I would move the validation call into a setUid method. And again it would make sense to make the validate method private and so it is difficult to test.

// Validation in set method 
class MachineId
{
    
    private $uid;
    
    public function __construct()
    {
        $this->uid = null;
    }    


    public function setUid(string $uid)
    {
        $this->uid = $uid;
        if($this->validate() === false) {
            // throw exception
        }
    }
    
    private function validate() : bool
    {
        ...
    }
    
}

$machineId = new MachineId();
$machineId->setUid($uid);

Should I create a validation class, that I also inject in the constructor?

// Validation with injecting a validation class

interface ValidatorInterface
{
    public function validate(mixed $value) : bool;
}

class MachineIdValidator implements ValidatorInterface
{
    public function validate($uid) : bool
    {
        ...
    }
}

class MachineId
{
    
    private $uid;
    
    public function __construct(string $uid, ValidatorInterface $validator)
    {
        if($validator->validate($uid) === false) {
            // throw exception
        }
        $this->uid = $uid;
    }    
}

$machineId = new MachineId($uid, new MachineIdValidator());

I run into this issue already many times and want to ask, if someone has a suggestion for a case like this. How to validate the string, without having a static method, but it is still testable and should not be forgotten?

我最喜歡的解決方案是創建一個 MachineId 的新實體并提供 uid 字串作為建構式引數。uid 應該經過驗證，并且驗證方法也應該是可測驗的。

uj5u.com熱心網友回復：

我最喜歡的解決方案是創建一個 MachineId 的新實體并提供 uid 字串作為建構式引數。uid 應該經過驗證，并且驗證方法也應該是可測驗的。

我認為您正在尋找類似的東西：

// Validation WHILE instantiation
class MachineId
{   
    private $uid;
    
    public function __construct(string $uid)
    {
        $this->uid = $uid;
        if(MachineId::validate($uid) === false) {
            // throw exception
        };
    }
    
    public static function validate(string $uid) : bool
    {
        ...
    }    
}

根據需要撰寫盡可能多的測驗，以確保 MachineId::validate 已正確實作。