#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    long long cost = 0;
    if (c0 > c1) {
      if (c1 + h <= c0) {
        int count0 = 0, count1 = 0;
        for (int i = 0; i < s.length(); i++) {
          if (s[i] == '0')
            count0++;
          else
            count1++;
        }
        cout << ((c1 + h) * count0) + ((c1)*count1) << "\n";
        continue;
      }
    } else if (c1 > c0) {
      if (c0 + h <= c1) {
        int count0 = 0, count1 = 0;
        for (int i = 0; i < s.length(); i++) {
          if (s[i] == '1')
            count1++;
          else
            count0++;
        }
        cout << ((c0 + h) * count1) + ((c0)*count0) << "\n";
        continue;
      }
    }
    cost = 0;
    for (int i = 0; i < s.length(); i++) {
      if (s[i] == '0')
        cost += c0;
      else
        cost += c1;
    }
    cout << cost << "\n";
  }
  return 0;
}
