#include <bits/stdc++.h>
using namespace std;
void solve() {
  int i;
  int n, c1, c0, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  int zero = 0, one = 0;
  for (i = 0; i < n; ++i) {
    if (s[i] == '0')
      zero++;
    else
      one++;
  }
  int ans = c0 * zero + c1 * one;
  ans = min(n * c0 + h * one, ans);
  ans = min(n * c1 + h * zero, ans);
  ans = min(c0 * one + c1 * zero + h * zero + h * one, ans);
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}
