How to best write Unit tests for this ?

.Question.txt

Hi, 

How would you write unit-test for this function? addFlushedPagesToCrawlerQueue()

With a functional test I would check the queue size, if the expected number of pages was added to the queue, 
but not sure how to deal with this in unit-tests.

Could you please give me some pointer.

I have added DataHandlerHookTests.php with an idea, but as I always expect null, I would not know which return route it has taken. Therefore... Bad Tests.. 

DatahandleHook.php

<?php

declare(strict_types=1);

namespace AOE\Crawler\Hooks;

use AOE\Crawler\Api\CrawlerApi;
use AOE\Crawler\Domain\Repository\QueueRepository;
use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Extbase\Object\ObjectManager;

class DataHandlerHook
{
    /**
     * @param array $parameters
     * @param \TYPO3\CMS\Core\DataHandling\DataHandler $dataHandler
     */
    public function addFlushedPagesToCrawlerQueue(array $parameters, \TYPO3\CMS\Core\DataHandling\DataHandler $dataHandler): void
    {
        if ($dataHandler->BE_USER->workspace > 0 && !$this->isWorkspacePublishAction($dataHandler->cmdmap)) {
            return;
        }

        $pageIdsToBeFlushedFromCache = $parameters['pageIdArray'];
        if (empty($pageIdsToBeFlushedFromCache)) {
            return;
        }
        foreach ($pageIdsToBeFlushedFromCache as $pageId) {
            $pageId = (int)$pageId;
            if ($pageId < 1) {
                continue;
            }
            if ($this->getQueueRepository()->isPageInQueue($pageId)) {
                continue;
            }
            $this->getCrawlerApi()->addPageToQueue($pageId);
        }
    }

    /**
     * Checks if a workspace record is being published
     *
     * Example $commandMap structure as provided by TYPO3:
     * 'pages' => array(
     *     123 => array(
     *         'version' => array(
     *             'action' => 'swap'
     *  [...]
     * 'tt_content' => array(
     *     456 => array(
     *         'version' => array(
     *             'action' => 'swap'
     * [...]
     *
     * @param array $commandMap
     * @return bool
     */
    protected function isWorkspacePublishAction(array $commandMap): bool
    {
        $isWorkspacePublishAction = false;
        foreach ($commandMap as $tableCommandMap) {
            if (!is_array($tableCommandMap)) {
                continue;
            }
            foreach ($tableCommandMap as $singleCommandMap) {
                if (!is_array($singleCommandMap)) {
                    continue;
                }
                if (!$this->isSwapAction($singleCommandMap)) {
                    continue;
                }
                $isWorkspacePublishAction = true;
                return $isWorkspacePublishAction;
            }
        }
        return $isWorkspacePublishAction;
    }

    /**
     * Checks if a page is being swapped with it's workspace overlay
     *
     * @param array $singleCommandMap
     * @return bool
     */
    private function isSwapAction(array $singleCommandMap): bool
    {
        $isSwapAction = false;
        if (
            isset($singleCommandMap['version'])
            && is_array($singleCommandMap['version'])
            && isset($singleCommandMap['version']['action'])
            && 'swap' === $singleCommandMap['version']['action']
        ) {
            $isSwapAction = true;
        }
        return $isSwapAction;
    }

    private function getQueueRepository(): QueueRepository
    {
        return GeneralUtility::makeInstance(ObjectManager::class)->get(QueueRepository::class);
    }

    private function getCrawlerApi(): CrawlerApi
    {
        return GeneralUtility::makeInstance(ObjectManager::class)->get(CrawlerApi::class);
    }
}

DataHandlerHookTest.php

<?php

declare(strict_types=1);

namespace AOE\Crawler\Tests\Unit\Hook;

use AOE\Crawler\Hooks\DataHandlerHook;
use Nimut\TestingFramework\TestCase\UnitTestCase;
use TYPO3\CMS\Core\DataHandling\DataHandler;

class DataHandlerHookTest extends UnitTestCase
{
    /**
     * @test
     * @dataProvider addFlushedPagesToCrawlerQueueTestDataProvider
     *
     * @param mixed $expected
     */
    public function addFlushedPagesToCrawlerQueueTest(array $params, int $WSId, bool $WSPublishAction, $expected): void
    {
        $dataHandler = self::createMock(DataHandler::class);
        $subject = self::createPartialMock(DataHandlerHook::class, ['isWorkspacePublishAction']);
        $subject->method('isWorkspacePublishAction')->willReturn($WSPublishAction);

        self::assertSame(
            $expected,
            $subject->addFlushedPagesToCrawlerQueue($params, $dataHandler)
        );
    }

    public function addFlushedPagesToCrawlerQueueTestDataProvider(): array
    {
        return [
            'WorkspaceID < 1' => [
                'params' => [],
                'workspace' => -1,
                'isWorkspacePublishAction' => true,
                'expected' => null,
            ],
            'WorkspaceID > 0 and workspace is publish action' => [
                'params' => [],
                'workspace' => 1,
                'isWorkspacePublishAction' => true,
                'expected' => null,
            ],
            'PageIdArray does not exist' => [
                'params' => [],
                'workspace' => 1,
                'isWorkspacePublishAction' => false,
                'expected' => null,
            ],
            'PageIdArray exist but is empty' => [
                'params' => ['pageIdArray' => []],
                'workspace' => 1,
                'isWorkspacePublishAction' => false,
                'expected' => null,
            ],
            'PageIdArray exists, but have 0 as pageId' => [
                'params' => ['pageIdArray' => [0]],
                'workspace' => 1,
                'isWorkspacePublishAction' => false,
                'expected' => null,
            ],
            'PageIdArray exists, have 1 as pageId, pageId 1 is in queue' => [
                'params' => ['pageIdArray' => []],
                'workspace' => 1,
                'isWorkspacePublishAction' => false,
                'expected' => null,
            ],
            'PageIdArray exists, have 1 as pageId, pageId 1 is not in queue' => [
                'params' => ['pageIdArray' => []],
                'workspace' => 1,
                'isWorkspacePublishAction' => false,
                'expected' => null,
            ],
        ];
    }

}