#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 str;
    cin >> str;
    int o = 0;
    int z = 0;
    for (int i = 0; i < n; i++)
      if (str[i] == '1')
        o++;
      else
        z++;
    if (c0 > c1 && c1 + h < c0)
      cout << z * h + c1 * (o + z) << endl;
    else if (c0 < c1 && c0 + h < c1)
      cout << o * h + c0 * (z + o) << endl;
    else
      cout << c0 * z + c1 * o << endl;
  }
}
