#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int t, i, c0, c1, n1, n0, h, n;
  cin >> t;
  string s;
  while (t--) {
    cin >> n >> c0 >> c1 >> h;
    cin >> s;
    n0 = 0;
    n1 = 0;
    for (i = 0; i < n; i++) {
      if (s[i] == '0')
        n0++;
      else
        n1++;
    }
    if (c0 == c1) {
      cout << c0 * n0 + c1 * n1 << endl;
    } else {
      if (c1 > c0) {
        if (h + c0 < c1) {
          cout << (h + c0) * n1 + c0 * n0 << endl;
        } else {
          cout << c0 * n0 + c1 * n1 << endl;
        }
      } else {
        if (h + c1 < c0) {
          cout << (h + c1) * n0 + c1 * n1 << endl;
        } else {
          cout << c1 * n1 + c0 * n0 << endl;
        }
      }
    }
  }
}
