Throwing a \Doctrine\DBAL\Driver\DriverException in a unit test mock

Question

Redacting unit tests, I am confronted to this problem. A piece of code that I want to test catches a \Doctrine\DBAL\Exception\RetryableException. The first constructor in the classes chain is the one of DriverException and is built like this :

/**
 * @param string                                $message         The exception message.
 * @param \Doctrine\DBAL\Driver\DriverException $driverException The DBAL driver exception to chain.
 */
public function __construct($message, \Doctrine\DBAL\Driver\DriverException $driverException)
{
    $exception = null;

    if ($driverException instanceof Exception) {
        $exception = $driverException;
    }

    parent::__construct($message, 0, $exception);

    $this->driverException = $driverException;
}

I feel like I am confronted to the problem of the egg and the chicken, here. How can I instanciante a class that takes an instance of itself as mandatory argument in the first place ?

Answer 1

Note: I won't mark this auto-response as a solution, it is more a workaround.

Instead of throwing the right exception in my unit test mock, I have created a simpler one, extending Exception but still implementing the original interface RetryableException, as it's the interface that is caught in the code I am testing. While not being what I wanted to do, it does the job in my precise case.

Answer 2

Here is how I have an actual instance of DriverException in my unit tests, using an anonymous class instead of a mock:

<?php

declare(strict_types=1);

use Doctrine\DBAL\Driver\Exception as TheDriverException;
use Doctrine\DBAL\Exception\DriverException;
use PHPUnit\Framework\TestCase;

final class MyTest extends TestCase
{
    // ... the rest of the test case

    private function getDriverExceptionWithCode(int $code): DriverException
    {
        $theDriverException = new class($code) extends \Exception implements TheDriverException {
            public function __construct(int $code)
            {
                parent::__construct('oh no, you broke it :(', $code);
            }

            public function getSQLState(): ?string
            {
                return null;
            }
        };

        return new DriverException($theDriverException, null);
    }
}

In my case I needed to unit test a situation where the code is catching a DriverException with a specific code, but you can extend the code as you wish, or make it simpler. The only thing you need is to implement getSQLState, after all.

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