@Test
    public void testClaimsOfCustomer2(){
        FileDatabase db = new FileDatabase();
        db.clearDatabase();
        Customer c1 = new Customer("Adam", "Klíma", 1);
        Customer c2 = new Customer("Lucas", "Sartore", 2);
        db.addCustomer(c1);
        db.addCustomer(c2);
        Claim claim1 = new Claim(c1,  10.0, 10.0, ClaimState.Paid);
        Claim claim2 = new Claim(c1, 15.0, 10.0, ClaimState.Paid);
        Claim claim3 = new Claim(c2, 15.0, 10.0, ClaimState.Paid);
        db.addClaim(claim1);
        db.addClaim(claim2);
        db.addClaim(claim3);
        Set expectedResult = new HashSet<Claim> ();
        expectedResult.add(claim3);
        assertEquals(expectedResult, db.getClaimsByCustomer(c2));
    }