Batch tearDownDrupal() entity cleanup into one storage delete() per type

Summary

DrupalTrait::tearDownDrupal() deletes every marked fixture entity one at a time:

foreach ($this->cleanupEntities as $entity) {
    $entity->delete();
}

For N fixtures, that's N separate single-entity storage deletes. EntityStorageInterface::delete() already accepts an array and fires the same per-entity hooks whether passed one entity or many, so the loop is pure round-trip overhead — worst in entity-heavy tests that create many nodes/users per method.

Proposed fix

Iterate in reverse creation order and issue one $storage->delete($batch) call per run of consecutive same-type entities:

$entity_type_manager = $this->container->get('entity_type.manager');
$batch = [];
$batch_entity_type_id = null;
foreach (array_reverse($this->cleanupEntities) as $entity) {
    $entity_type_id = $entity->getEntityTypeId();
    if ($entity_type_id !== $batch_entity_type_id && $batch !== []) {
        $entity_type_manager->getStorage($batch_entity_type_id)->delete($batch);
        $batch = [];
    }
    $batch_entity_type_id = $entity_type_id;
    $batch[] = $entity;
}
if ($batch !== []) {
    $entity_type_manager->getStorage($batch_entity_type_id)->delete($batch);
}

Risk

Ordering is preserved — later-created entities still delete first, and each call handles only one type, so cross-type dependency ordering can't be violated. $storage->delete([$a, $b]) fires the same per-entity hooks as N individual calls, and bucketing only consecutive same-type runs keeps interleaved-type ordering intact.

Measured impact

Near-zero saving on tests with one or two entities, largest on entity-heavy classes. Measured together with two related fixes (pre-flight visit skip, watchdog memoization), the combined per-test body time dropped roughly 5.75s → ~3.9s on a smoke-test probe. Verified with a behavior test driving the real tearDownDrupal() with interleaved node/user fixtures, confirming every one is gone afterward.

Patch

Attached: dtt-batched-entity-cleanup.patch (against 2.7.0 tip). Replaces the per-entity delete loop in src/DrupalTrait.php::tearDownDrupal() with the batched approach above. Includes the interleaved-fixture behavior test.

AI-assistance disclosure

Per drupal.org's policy on AI use in contributions: AI-Generated: Yes. An AI coding assistant helped draft this patch and write-up under my direction. I reviewed the change, ran its behavior test locally, and confirmed the measured numbers come from real test runs — not generated. I take full responsibility for its correctness and will respond to maintainer feedback on this issue.