/**
  * Test if rollback rolls-back multi-level transaction.
  */
 public function testRollbackMultipleLevels()
 {
     $this->assertFalse($this->connection->inTransaction());
     // First level
     $this->connection->beginWork();
     $this->assertTrue($this->connection->inTransaction());
     // Second level
     $this->connection->beginWork();
     $this->assertTrue($this->connection->inTransaction());
     // Rollback everything
     $this->connection->rollback();
     $this->assertFalse($this->connection->inTransaction());
 }