#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    int len = s.length();
    int cnt = 0;
    if (c0 < c1) {
      for (int i = 0; i < n; i++) {
        if (s[i] == '1') {
          cnt++;
        }
      }
      int ans = (c0 * len) + (cnt * h);
      if (ans > (cnt * c1) + ((len - cnt) * c0))
        cout << (cnt * c1) + ((len - cnt) * c0) << "\n";
      else
        cout << ans << "\n";
    } else if (c0 > c1) {
      for (int i = 0; i < n; i++) {
        if (s[i] == '0') {
          cnt++;
        }
      }
      int ans = (c1 * len) + (cnt * h);
      if (ans > (cnt * c0) + ((len - cnt) * c1))
        cout << (cnt * c0) + ((len - cnt) * c1) << "\n";
      else
        cout << ans << "\n";
    } else {
      for (int i = 0; i < n; i++) {
        if (s[i] == '1') {
          cnt++;
        }
      }
      cout << (cnt * c1) + ((len - cnt) * c0) << "\n";
    }
  }
  return 0;
}
