DatabaseStorage, readMultiple throws error when receive empty array

Believe we need to investigate the steps that trigger this. Could be masking a larger issue

Will need test coverage as well.

Not in a spot to create a test at the moment however here is a real world sample from a ServiceProvider: This can be made into a test by injecting config.storage.active and calling readMultiple([]);

  public function register(ContainerBuilder $container): void {
    /** @var \Drupal\Core\Config\StorageInterface $config_storage */
    $config_storage = $container->get('config.storage.active');
    $entity_config_names = $config_storage->listAll('some_module.match_nothing');
    $configured_entities = $config_storage->readMultiple($entity_config_names);
 }

The reason config.storage does not see this is it attempts to generate a cache tag for each requested entry, when it is empty no cache tags are generated and when no cache tags are generated config.storage does not try and call inner storage. This appears to be more accidental around making sure cache tags exist rather than intentionally protecting DatabaseStorage::readMultiple() from an empty read.

StorageInterface::readMultiple() does not specify it must be a non-empty-array making readMultiple([]) valid per the interface.

Clearing need steps to reproduce as that is documented.

Perfect test-only job has already been ran https://git.drupalcode.org/issue/drupal-3416525/-/jobs/2118936

Thanks also for adding the steps and summary update. Confirmed solution matches what's in the MR.

Code wise the early return looks fine.

Believe this may be good.

Can the test be added to \Drupal\KernelTests\Core\Config\Storage\ConfigStorageTestBase::testCRUD() and then all config storage types will be tested for the same behaviour.

Trivial change to implement #9

Did switch from an assertEquals() to assertSame() while migrating to be slightly more type strict.

The test only script appears to be broken when changing a base class.

$ $CI_PROJECT_DIR/.gitlab-ci/scripts/test-only.sh
ℹ️ Changes from 2e311a8d3fb7015cf2fa3615e3843caf0d90a4af
core/lib/Drupal/Core/Config/DatabaseStorage.php
core/tests/Drupal/KernelTests/Core/Config/Storage/ConfigStorageTestBase.php
If this list contains more files than what you changed, then you need to rebase your branch.
1️⃣ Reverting non test changes
grep: warning: * at start of expression
grep: warning: * at start of expression
↩️ Reverting core/lib/Drupal/Core/Config/DatabaseStorage.php
grep: warning: * at start of expression
2️⃣ Running test changes for this branch
Exiting with EXIT_CODE=0

Tried rebasing but test-only still wasn't showing much. So started a test-only branch to see if that's any better.

https://git.drupalcode.org/issue/drupal-3416525/-/jobs/2374011 shows the test coverage.

Committed/pushed to 11.x and cherry-picked back through to 10.3.x, thanks!

catch → closed merge request !8764

Automatically closed - issue fixed for 2 weeks with no activity.