@Test
public void checkCoinNameExistMultipleNames() {

    ConcurrentHashMap<String, String> coins = new ConcurrentHashMap<>();
    coins.put("Contract", "");
    coins.put("Contract(3)", "");
    coins.put("Contract(1)", "");
    coins.put("Contract(2)", "");
    assertEquals("Contract(4)", checkCoinNameExist("Contract", coins));
}