#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, c1, c2, h;
    cin >> n >> c1 >> c2 >> h;
    int zero = 0, one = 0;
    int cost = 0;
    for (int i = 0; i < n; i++) {
      char ch;
      cin >> ch;
      if (ch == '0')
        cost += min(h + c2, c1);
      else
        cost += min(h + c1, c2);
    }
    cout << cost << endl;
  }
}
