#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int ans = 0;
    int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    if (c0 == c1) {
      ans = n * c0;
    } else if (c0 < c1) {
      int n1 = 0;
      for (int i = 0; i < n; i++) {
        if (s[i] == '1') n1++;
      }
      if (h + c0 < c1) {
        ans = n1 * (h + c0) + (n - n1) * c0;
      } else {
        ans = n1 * c1 + (n - n1) * c0;
      }
    } else {
      int n0 = 0;
      for (int i = 0; i < n; i++) {
        if (s[i] == '0') n0++;
      }
      if (h + c1 < c0) {
        ans = n0 * (h + c1) + (n - n0) * c1;
      } else {
        ans = n0 * c0 + (n - n0) * c1;
      }
    }
    cout << ans << endl;
  }
  return (0);
}
