#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int T;
  cin >> T;
  while (T-- > 0) {
    int n, c1, c2, h, minimum = 0;
    cin >> n >> c1 >> c2 >> h;
    string s;
    cin >> s;
    for (int i = 0; i < n; i++) {
      if (s[i] == '0')
        minimum += min(c1, (c2 + h));
      else if (s[i] == '1')
        minimum += min(c2, (c1 + h));
    }
    cout << minimum << endl;
  }
}
