#include <bits/stdc++.h>
using namespace std;
long long const mo = 1e9 + 7;
long long mod(long long k) { return (k + mo) % mo; }
long long addmod(long long a, long long b) { return mod(mod(a) + mod(b)); }
long long mulmod(long long a, long long b) { return mod(mod(a) * mod(b)); }
long long submod(long long a, long long b) {
  return mod(a % mo - b % mo + mo) % mo;
}
void solve() {
  int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  int cnt0 = 0, cnt1 = 0;
  for (char c : s) {
    if (c == '1')
      ++cnt1;
    else
      ++cnt0;
  }
  cout << min({cnt0 * c0 + cnt1 * c1, cnt0 * h + (n)*c1, cnt1 * h + (n)*c0})
       << "\n";
}
int main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed;
  cout.precision(20);
  ;
  int t = 1;
  cin >> t;
  for (int i = 1; i <= t; ++i) {
    solve();
  }
  return 0;
}
