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