#include <bits/stdc++.h>
using namespace std;
int T;
int main() {
  cin >> T;
  while (T--) {
    int n, c1, c2, h;
    cin >> n >> c1 >> c2 >> h;
    int veg = 0;
    string s;
    cin >> s;
    for (int i = 0; i < n; i++) {
      if (s[i] == '0') {
        veg += min(c1, c2 + h);
      } else {
        veg += min(c2, c1 + h);
      }
    }
    cout << veg << endl;
  }
  return 0;
}
