Phpunit testing callback functions when passing them to a stub method - phpunit

Question

Here is the method to test.
public function performPoolRequest(RecreationRequestsCollection $requests): RecreatedPaymentsPoolReading
{
$count_request = count($requests);
if($count_request) {
$pool_recreate_payments = new RecreatedPaymentsPool();
$this->http_client->sendPoolRequest(
$this->generateRequests($requests),
$count_request,
function (ResponseInterface $response, $index) use ($requests, $pool_recreate_payments) {
$this->successHandler($response, $requests, $index, $pool_recreate_payments);
},
function (BadResponseException $reason, $index) use ($requests, $pool_recreate_payments) {
$this->failureHandler($reason, $requests, $index, $pool_recreate_payments);
}
);
return $pool_recreate_payments;
} else {
throw new PoolRequestException('Incorrect amount of requests: ' . $count_request);
}
}
Difficulties arose with this piece of code:
$this->http_client->sendPoolRequest(
$this->generateRequests($requests),
$count_request,
function (ResponseInterface $response, $index) use ($requests, $pool_recreate_payments) {
$this->successHandler($response, $requests, $index, $pool_recreate_payments);
},
function (BadResponseException $reason, $index) use ($requests, $pool_recreate_payments) {
$this->failureHandler($reason, $requests, $index, $pool_recreate_payments);
}
);
I made a mock object $this->http_client
But I don't know how to test methods in the argumets ($this->successHandler, $this->failureHandler, this->generateRequests($requests)) that are sent to the method sendPoolRequest.
All of these methods are protected. I understand how to test them using a reflection object, but I want to know if there is an option to test them within a single test by checking the values in $ pool_recreate_payments.

Answer 1

You have to fake what the http client is doing in some way. That means: actually calling the callback functions. While it might be possible to do that with a PHPUnit mock object, writing own test doubles is often easier.
Here are a few examples to get you started.
public function testAllFailing()
{
$client = new class implements HttpClient {
public function sendPoolRequest(array $requests, int $numRequests, callable $successHandler, callable $errorHandler)
{
foreach ($requests as $index => $request) {
$errorHandler(new BadResponseException(/*...*/), $index);
}
}
};
$myService = new MyService($client);
$result = $myService->performPoolRequest(/*...*/);
self::assertEquals(/*...*/, $result);
}
public function testAllSucceeding()
{
$client = new class implements HttpClient {
public function sendPoolRequest(array $requests, int $numRequests, callable $successHandler, callable $errorHandler)
{
foreach ($requests as $index => $request) {
$successHandler(new Response(/*...*/), $index);
}
}
};
$myService = new MyService($client);
$result = $myService->performPoolRequest(/*...*/);
self::assertEquals(/*...*/, $result);
}
public function testEveryOtherFails()
{
$client = new class implements HttpClient {
public function sendPoolRequest(array $requests, int $numRequests, callable $successHandler, callable $errorHandler)
{
foreach ($requests as $index => $request) {
if ($index % 2 === 0) {
$successHandler(new Response(/*...*/), $index);
} else {
$errorHandler(new BadResponseException(/*...*/), $index);
}
}
}
};
$myService = new MyService($client);
$result = $myService->performPoolRequest(/*...*/);
self::assertEquals(/*...*/, $result);
}

Answer 2

Since Guzzle is used as the http client, I decided to use its capabilities in terms of creating stubs for the response object. Here is a link to the documentation Guzzle documentation. The solution turned out to be simple and allowed us to extensively test the business logic of the response.