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