#include <bits/stdc++.h>
using namespace std;
int main() {
  int t, n, c0, c1, h, cc0 = 0, cc1 = 0;
  cin >> t;
  cout << endl;
  for (int i = 0; i < t; i++) {
    cin >> n >> c0 >> c1 >> h;
    cout << endl;
    string ali;
    cin >> ali;
    bitset<1001> ss(ali);
    cc1 = ss.count();
    cc0 = n - cc1;
    int min_d = (cc1 * c1) + (cc0 * c0);
    if (c0 < c1) {
      int maliyet = cc1 * c0 + cc0 * c0 + cc1 * h;
      min_d = min(min_d, maliyet);
    } else {
      int maliyet = cc1 * c1 + cc0 * c1 + cc0 * h;
      min_d = min(min_d, maliyet);
    }
    cout << endl << min_d << endl;
  }
  return 0;
}
