diff --git a/core/modules/layout_builder/tests/fixtures/update/layout-builder.php b/core/modules/layout_builder/tests/fixtures/update/layout-builder.php
--- /dev/null
+++ b/core/modules/layout_builder/tests/fixtures/update/layout-builder.php
@@ -0,0 +1,54 @@
-<?php
-
-/**
- * @file
- * Test fixture.
- */
-
-use Drupal\Core\Database\Database;
-
-$connection = Database::getConnection();
-
-// Set the schema version.
-$connection->merge('key_value')
-  ->fields(['value' => 'i:8602;'])
-  ->condition('collection', 'system.schema')
-  ->condition('name', 'layout_builder')
-  ->execute();
-
-// Update core.extension.
-$extensions = $connection->select('config')
-  ->fields('config', ['data'])
-  ->condition('collection', '')
-  ->condition('name', 'core.extension')
-  ->execute()
-  ->fetchField();
-$extensions = unserialize($extensions);
-$extensions['module']['layout_builder'] = 0;
-$extensions['module']['layout_discovery'] = 0;
-$connection->update('config')
-  ->fields(['data' => serialize($extensions)])
-  ->condition('collection', '')
-  ->condition('name', 'core.extension')
-  ->execute();
-
-// Add all layout_builder_removed_post_updates() as existing updates.
-require_once __DIR__ . '/../../../../layout_builder/layout_builder.post_update.php';
-require_once __DIR__ . '/../../../../layout_discovery/layout_discovery.post_update.php';
-$existing_updates = $connection->select('key_value')
-  ->fields('key_value', ['value'])
-  ->condition('collection', 'post_update')
-  ->condition('name', 'existing_updates')
-  ->execute()
-  ->fetchField();
-$existing_updates = unserialize($existing_updates);
-$existing_updates = array_merge(
-  $existing_updates,
-  array_keys(layout_builder_removed_post_updates()),
-  array_keys(layout_discovery_removed_post_updates())
-);
-$connection->update('key_value')
-  ->fields(['value' => serialize($existing_updates)])
-  ->condition('collection', 'post_update')
-  ->condition('name', 'existing_updates')
-  ->execute();