Convert driver exceptions when starting transactions

src/Connection.php

@@ -1027,7 +1027,11 @@
         ++$this->transactionNestingLevel;
 
         if ($this->transactionNestingLevel === 1) {
-            $connection->beginTransaction();
+            try {
+                $connection->beginTransaction();
+            } catch (Driver\Exception $e) {
+                throw $this->convertException($e);
+            }
         } else {
             $this->createSavepoint($this->_getNestedTransactionSavePointName());
         }

src/Driver/API/PostgreSQL/ExceptionConverter.php

@@ -7,6 +7,7 @@
 use Doctrine\DBAL\Driver\API\ExceptionConverter as ExceptionConverterInterface;
 use Doctrine\DBAL\Driver\Exception;
 use Doctrine\DBAL\Exception\ConnectionException;
+use Doctrine\DBAL\Exception\ConnectionLost;
 use Doctrine\DBAL\Exception\DatabaseDoesNotExist;
 use Doctrine\DBAL\Exception\DeadlockException;
 use Doctrine\DBAL\Exception\DriverException;
@@ -77,6 +78,10 @@
                 return new ConnectionException($exception, $query);
         }
 
+        if (str_contains($exception->getMessage(), 'terminating connection')) {
+            return new ConnectionLost($exception, $query);
+        }
+
         return new DriverException($exception, $query);
     }
 }

src/Driver/Mysqli/Connection.php

@@ -80,7 +80,9 @@ public function lastInsertId(): int|string
 
     public function beginTransaction(): void
     {
-        $this->connection->begin_transaction();
+        if (! $this->connection->begin_transaction()) {
+            throw ConnectionError::new($this->connection);
+        }
     }
 
     public function commit(): void

tests/Functional/TransactionTest.php

@@ -7,45 +7,48 @@
 use Doctrine\DBAL\Connection;
 use Doctrine\DBAL\Exception\ConnectionLost;
 use Doctrine\DBAL\Platforms\AbstractMySQLPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQLPlatform;
 use Doctrine\DBAL\Schema\Table;
 use Doctrine\DBAL\Tests\FunctionalTestCase;
+use Doctrine\DBAL\Tests\TestUtil;
 use Doctrine\DBAL\Types\Types;
 
 use function func_get_args;
 use function restore_error_handler;
 use function set_error_handler;
-use function sleep;
 
 use const E_WARNING;
 
 class TransactionTest extends FunctionalTestCase
 {
+    public function testBeginTransactionFailure(): void
+    {
+        $this->expectConnectionLoss(static function (Connection $connection): void {
+            $connection->beginTransaction();
+        });
+    }
+
     public function testCommitFailure(): void
     {
+        $this->connection->beginTransaction();
+
         $this->expectConnectionLoss(static function (Connection $connection): void {
             $connection->commit();
         });
     }
 
     public function testRollbackFailure(): void
     {
+        $this->connection->beginTransaction();
+
         $this->expectConnectionLoss(static function (Connection $connection): void {
             $connection->rollBack();
         });
     }
 
     private function expectConnectionLoss(callable $scenario): void
     {
-        if (! $this->connection->getDatabasePlatform() instanceof AbstractMySQLPlatform) {
-            self::markTestSkipped('Restricted to MySQL.');
-        }
-
-        $this->connection->executeStatement('SET SESSION wait_timeout=1');
-        $this->connection->beginTransaction();
-
-        // during the sleep MySQL will close the connection
-        sleep(2);
-
+        $this->killCurrentSession();
         $this->expectException(ConnectionLost::class);
 
         // prevent the PHPUnit error handler from handling the "MySQL server has gone away" warning
@@ -65,6 +68,31 @@ private function expectConnectionLoss(callable $scenario): void
         }
     }
 
+    private function killCurrentSession(): void
+    {
+        $this->markConnectionNotReusable();
+
+        $databasePlatform = $this->connection->getDatabasePlatform();
+
+        [$currentProcessQuery, $killProcessStatement] = match (true) {
+            $databasePlatform instanceof AbstractMySqlPlatform => [
+                'SELECT CONNECTION_ID()',
+                'KILL ?',
+            ],
+            $databasePlatform instanceof PostgreSQLPlatform => [
+                'SELECT pg_backend_pid()',
+                'SELECT pg_terminate_backend(?)',
+            ],
+            default => self::markTestSkipped('Unsupported test platform.'),
+        };
+
+        $privilegedConnection = TestUtil::getPrivilegedConnection();
+        $privilegedConnection->executeStatement(
+            $killProcessStatement,
+            [$this->connection->executeQuery($currentProcessQuery)->fetchOne()],
+        );
+    }
+
     public function testNestedTransactionWalkthrough(): void
     {
         if (! $this->connection->getDatabasePlatform()->supportsSavepoints()) {