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