#include <bits/stdc++.h>
using namespace std;
int main() {
  long long t;
  cin >> t;
  while (t--) {
    long long n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    long long zero = 0, one = 0;
    for (int i = 0; i < n; i++) {
      if (s[i] == '0') {
        zero++;
      } else
        one++;
    }
    if (c0 < c1) {
      long long ans1 = zero * c0;
      if (h + c0 < c1) {
        ans1 += ((h + c0) * one);
      } else {
        ans1 += c1 * one;
      }
      cout << ans1 << '\n';
    } else {
      long long ans2 = one * c1;
      if (h + c1 < c0) {
        ans2 += ((h + c1) * zero);
      } else {
        ans2 += c0 * zero;
      }
      cout << ans2 << '\n';
    }
  }
}
