Cover scenario `BEGIN TRANSACTION; COMMIT; BEGIN TRANSACTION --failure;

#6545 (comment)

tests/ConnectionTest.php

@@ -32,6 +32,7 @@
 use PHPUnit\Framework\TestCase;
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
+use RuntimeException;
 use stdClass;
 
 /** @requires extension pdo_mysql */
@@ -455,6 +456,35 @@ public function testCommitStartsTransactionInNoAutoCommitMode(): void
         self::assertTrue($conn->isTransactionActive());
     }
 
+    public function testCoverBeginTransactionFailureAfterCommitInNoAutoCommitMode(): void
+    {
+        $driverConnectionMock = $this->createMock(DriverConnection::class);
+        $driverConnectionMock->expects(self::exactly(2))
+            ->method('beginTransaction')
+            ->willReturnOnConsecutiveCalls(
+                true,
+                self::throwException(new RuntimeException()),
+            );
+
+        $driverMock = $this->createMock(Driver::class);
+        $driverMock->expects(self::any())
+            ->method('connect')
+            ->willReturn(
+                $driverConnectionMock,
+            );
+        $conn = new Connection([], $driverMock);
+
+        $conn->setAutoCommit(false);
+
+        $conn->connect();
+        try {
+            $conn->commit();
+        } catch (RuntimeException $e) {
+        }
+
+        self::assertTrue($conn->isTransactionActive());
+    }
+
     /** @dataProvider resultProvider */
     public function testCommitReturn(bool $expectedResult): void
     {