#include <bits/stdc++.h>
using namespace std;
int T, n, c0, c1, h;
int main() {
  cin >> T;
  while (T--) {
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    int on = 0, ze = 0;
    for (int i = 0; i < n; ++i) {
      if (s[i] == '1')
        on++;
      else
        ze++;
    }
    c0 = min(c0, c1 + h);
    c1 = min(c1, c0 + h);
    cout << on * c1 + ze * c0 << '\n';
  }
}
