QSqlDatabase::open always returns true with QMYSQL

QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
db.setHostName("unreachable");
db.setPort(3306);
db.setDatabaseName("test");
db.setUserName("username");
db.setPassword("password");
if (!db.open()) {
    qDebug() << "Failed to open database" << db.lastError().databaseText();
} else {
    qDebug() << "Success";
}