#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 second;
    cin >> second;
    int cost1 = 0, z = 0, o = 0;
    for (int i = 0; i < second.length(); i++) {
      if (second[i] == '0') {
        cost1 += c0;
        z++;
      } else {
        cost1 += c1;
        o++;
      }
    }
    int cost2 = o * h + c0 * (second.length());
    int cost3 = z * h + c1 * (second.length());
    cout << min(cost1, min(cost2, cost3)) << endl;
  }
  return 0;
}
