Issue #3123461 by daffie, Kristen Pol, alexpott, xjm: Deprecate support for...

Issue #3123461 by daffie, Kristen Pol, alexpott, xjm: Deprecate support for database drivers placed in DRUPAL_ROOT/drivers

core/lib/Drupal/Core/Database/Connection.php

@@ -214,6 +214,7 @@ public function __construct(\PDO $connection, array $connection_options) {
       @trigger_error('In drupal:10.0.0 not setting the $identifierQuotes property in the concrete Connection class will result in an RuntimeException. See https://www.drupal.org/node/2986894', E_USER_DEPRECATED);
       $this->identifierQuotes = ['', ''];
     }
+
     assert(count($this->identifierQuotes) === 2 && Inspector::assertAllStrings($this->identifierQuotes), '\Drupal\Core\Database\Connection::$identifierQuotes must contain 2 string values');
     // The 'transactions' option is deprecated.
     if (isset($connection_options['transactions'])) {
@@ -228,6 +229,12 @@ public function __construct(\PDO $connection, array $connection_options) {
       $connection_options['namespace'] = (new \ReflectionObject($this))->getNamespaceName();
     }
 
+    // The support for database drivers where the namespace that starts with
+    // Drupal\\Driver\\Database\\ is deprecated.
+    if (strpos($connection_options['namespace'], 'Drupal\Driver\Database') === 0) {
+      @trigger_error('Support for database drivers located in the "drivers/lib/Drupal/Driver/Database" directory is deprecated in drupal:9.1.0 and is removed in drupal:10.0.0. Contributed and custom database drivers should be provided by modules and use the namespace "Drupal\MODULE_NAME\Driver\Database\DRIVER_NAME". See https://www.drupal.org/node/3123251', E_USER_DEPRECATED);
+    }
+
     // Initialize and prepare the connection prefix.
     $this->setPrefix(isset($connection_options['prefix']) ? $connection_options['prefix'] : '');
 

core/tests/Drupal/Tests/Core/Database/ConditionTest.php

@@ -187,7 +187,7 @@ public function testContribCondition() {
       ->setConstructorArgs([NULL])
       ->disableOriginalConstructor()
       ->getMock();
-    $contrib_namespace = 'Drupal\Driver\Database\mock';
+    $contrib_namespace = 'Drupal\mock\Driver\Database\mock';
     $mocked_namespace = $contrib_namespace . '\\Condition';
     class_alias('MockCondition', $mocked_namespace);
 

core/tests/Drupal/Tests/Core/Database/ConnectionTest.php

@@ -668,7 +668,20 @@ public function provideQueriesToTrim() {
         'SELECT * FROM test; ',
         ['allow_delimiter_in_query' => TRUE],
       ],
-   ];
+    ];
+  }
+
+  /**
+   * Tests the deprecation of Drupal 8 style database drivers.
+   *
+   * @group legacy
+   * @expectedDeprecation Support for database drivers located in the "drivers/lib/Drupal/Driver/Database" directory is deprecated in drupal:9.1.0 and is removed in drupal:10.0.0. Contributed and custom database drivers should be provided by modules and use the namespace "Drupal\MODULE_NAME\Driver\Database\DRIVER_NAME". See https://www.drupal.org/node/3123251
+   */
+  public function testLegacyDatabaseDriverInRootDriversDirectory() {
+    $namespace = 'Drupal\\Driver\\Database\\Stub';
+    $mock_pdo = $this->createMock(StubPDO::class);
+    $connection = new StubConnection($mock_pdo, ['namespace' => $namespace], ['"', '"']);
+    $this->assertEquals($namespace, $connection->getConnectionOptions()['namespace']);
   }
 
 }