#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  long long int t;
  cin >> t;
  while (t--) {
    long long int cost = 0, sum = 0, c = 0, summ = 0;
    string s;
    long long int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    cin >> s;
    for (long long int i = 0; i < n; i++) {
      if (s[i] == '1')
        cost += c1;
      else
        cost += c0;
      sum += c1;
      summ += c0;
    }
    for (long long int i = 0; i < n; i++) {
      if (s[i] == '0')
        sum += h;
      else
        summ += h;
    }
    cout << min(sum, min(summ, cost)) << endl;
  }
}
