#include <bits/stdc++.h>
using namespace std;
int main() {
  int t, n, c0, c1, h, n0, n1, ans, ans1, ans2, ans3;
  string a;
  cin >> t;
  while (t--) {
    cin >> n >> c0 >> c1 >> h;
    cin >> a;
    n0 = 0;
    for (int i = 0; i < n; i++) {
      if (a[i] == '0') n0++;
    }
    n1 = n - n0;
    ans1 = n0 * c0 + n1 * c1;
    ans2 = n0 * h + n * c1;
    ans3 = n1 * h + n * c0;
    ans = min(ans1, min(ans2, ans3));
    cout << ans << endl;
  }
  return 0;
}
