#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  int t, n, c_0, c_1, h;
  string s;
  cin >> t;
  for (int i = 0; i < t; i++) {
    cin >> n >> c_0 >> c_1 >> h;
    cin >> s;
    int sum = 0;
    for (int j = 0; j < n; j++) {
      sum += s[j] - '0';
    }
    if (c_0 - c_1 > h) {
      sum = c_1 * n + (n - sum) * h;
    } else if (c_1 - c_0 > h) {
      sum = c_0 * n + sum * h;
    } else
      sum = c_1 * sum + (n - sum) * c_0;
    cout << sum << endl;
  }
  return 0;
}
