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