Issue #3152320 by bircher, nedjo, tstoeckler:...

    return new static(

      $this->configStorage,

      $this->directory,

      $collection

      $collection,

      $this->includeProfile,

      $this->installProfile

    );

  }

<?php

namespace Drupal\Tests\Core\Config;

use Drupal\Core\Config\ExtensionInstallStorage;

use Drupal\Core\Config\InstallStorage;

use Drupal\Core\Config\MemoryStorage;

use Drupal\Core\Config\StorageInterface;

use Drupal\Tests\UnitTestCase;

/**

 * @coversDefaultClass \Drupal\Core\Config\ExtensionInstallStorage

 * @group Config

 */

class ExtensionInstallStorageTest extends UnitTestCase {

  /**

   * @covers ::createCollection

  */

  public function testCreateCollection() {

    $memory = new MemoryStorage();

    $include_profile = FALSE;

    $profile = $this->randomMachineName();

    $collectionName = $this->randomMachineName();

    // Set up the storage.

    $storage = new ExtensionInstallStorage($memory, InstallStorage::CONFIG_INSTALL_DIRECTORY, StorageInterface::DEFAULT_COLLECTION, $include_profile, $profile);

    // Create a collection.

    $collection = $storage->createCollection($collectionName);

    static::assertEquals($collectionName, $collection->getCollectionName());

  }

}