Issue #3463226 by quietone, dww, smustgrave, catch, xjm: Use the new...

Issue #3463226 by quietone, dww, smustgrave, catch, xjm: Use the new equivalent updates API to prevent updates from 10.4.0 to 11.0.0

core/modules/system/system.install

@@ -1939,3 +1939,12 @@ function system_update_10201(&$sandbox) {
 
   $sandbox['#finished'] = $sandbox['current_key'] == $sandbox['max'];
 }
+
+/**
+ * Equivalent update to 11102.
+ */
+function system_update_10400(): void {
+  // This is a no-op that exists to prevent an upgrade from 10.4+ to 11.0. That
+  // path is actually a downgrade.
+  \Drupal::service('update.update_hook_registry')->markFutureUpdateEquivalent(11102, '11.1.0');
+}

core/modules/system/tests/modules/downgrade_prevention_test/downgrade_prevention_test.info.yml

+name: '10.4 downgrade prevention test'
+type: module
+description: 'Support module for testing that an update hook prevents a downgrade.'
+package: Testing
+version: VERSION

core/modules/system/tests/modules/downgrade_prevention_test/downgrade_prevention_test.install

+<?php
+
+/**
+ * @file
+ * Update hooks and schema definition for the downgrade_prevention_test module.
+ */
+
+declare(strict_types=1);
+
+/**
+ * A hook_update_N that is equivalent update to 10400.
+ */
+function downgrade_prevention_test_update_11102(): void {
+}

core/modules/system/tests/src/Functional/UpdateSystem/PreventDowngradeTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\system\Functional\UpdateSystem;
+
+use Drupal\FunctionalTests\Update\UpdatePathTestBase;
+
+/**
+ * Tests that a site on 10.4.0 is prevented from downgrading to 11.0.0.
+ *
+ * This tests the upgrade path when there is a pair of equivalent updates. The
+ * earlier update is 10400 and the latter one is 11102.
+ *
+ * @group Update
+ */
+class PreventDowngradeTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setDatabaseDumpFiles(): void {
+    $this->databaseDumpFiles[] = __DIR__ . '/../../../../tests/fixtures/update/drupal-10.3.0.filled.standard.php.gz';
+  }
+
+  /**
+   * Tests prevention of incorrect update path.
+   */
+  public function testDowngradePrevention(): void {
+    $database = \Drupal::database();
+
+    // Record the update 10400 as an equivalent to update 11102.
+    $database->insert('key_value')
+      ->fields([
+        'collection' => 'core.equivalent_updates',
+        'name' => 'downgrade_prevention_test',
+        'value' => 'a:1:{i:11102;a:2:{s:10:"ran_update";s:5:"10400";s:21:"future_version_string";s:6:"11.1.0";}}',
+      ])
+      ->execute();
+
+    // Set the test module schema to 10400.
+    $database->insert('key_value')
+      ->fields([
+        'value' => 'i:10400;',
+        'collection' => 'system.schema',
+        'name' => 'downgrade_prevention_test',
+      ])
+      ->execute();
+
+    // Running the updates should fail with a requirements failure because the
+    // later update, 11102, is missing from the code base.
+    try {
+      $this->runUpdates();
+    }
+    catch (\Exception) {
+      // Continue.
+    }
+    $this->assertSession()->pageTextContains('Missing updates for: 10.4 downgrade prevention test');
+    $this->assertSession()->pageTextContains('The version of the 10.4 downgrade prevention test module that you are attempting to update to is missing update 11102 (which was marked as an equivalent by 10400). Update to at least Drupal Core 11.1.0.');
+
+    // Repeat the test with a code base that does have the 11102 update,
+    // downgrade_prevention_test_update_11102(). First, install
+    // downgrade_prevention_test.
+    $extensions = $database->select('config')
+      ->fields('config', ['data'])
+      ->condition('collection', '')
+      ->condition('name', 'core.extension')
+      ->execute()
+      ->fetchField();
+    $extensions = unserialize($extensions);
+
+    // Install the 'downgrade_prevention_test' module.
+    $extensions['module']['downgrade_prevention_test'] = 0;
+    $database->update('config')
+      ->fields([
+        'data' => serialize($extensions),
+      ])
+      ->condition('collection', '')
+      ->condition('name', 'core.extension')
+      ->execute();
+
+    // Set the schema for 'downgrade_prevention_test' to the update function, 11102.
+    $database->update('key_value')
+      ->fields([
+        'value' => 'i:11102;',
+      ])
+      ->condition('collection', 'system.schema')
+      ->condition('name', 'downgrade_prevention_test')
+      ->execute();
+
+    // Running the updates should succeed because the 11102 update function,
+    // downgrade_prevention_test_update_11102(), now exists.
+    $this->runUpdates();
+
+    $this->assertSession()->pageTextContains('Updates were attempted.');
+  }
+
+}