test class for read file function

Can someone help me to write a test class to my readFile function?

public void readFileCidadao() {
    Set<Cidadao> cidadaos = new HashSet<>();
    try {
        Scanner in = new Scanner(new File("src\files\fx_cidadaos.txt"));
        while (in.hasNextLine()) {
            String linha = in.nextLine();
            String partes[] = linha.split(",");
            Cidadao cidadao = new Cidadao(partes[0], Integer.parseInt(partes[1]), partes[2], partes[3], Integer.parseInt(partes[4]));
    } catch (FileNotFoundException e) {
        System.out.println("File Not Found");