#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 s;
    cin >> s;
    int o = 0, z = 0;
    for (int i = 0; i < n; i++) {
      if (s[i] == '1')
        o++;
      else
        z++;
    }
    int ans = 0;
    if (c0 < c1) {
      if (c0 + h <= c1)
        ans = z * c0 + o * (c0 + h);
      else
        ans = z * c0 + o * c1;
    } else {
      if (c1 + h <= c0)
        ans = c1 * o + z * (c1 + h);
      else
        ans = c1 * o + c0 * z;
    }
    cout << ans << endl;
  }
  return 0;
}
