#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, c0, c1, h;
  string s;
  cin >> n >> c0 >> c1 >> h;
  cin >> s;
  long long n0 = 0, n1 = 0;
  for (long long i = 0; i < n; i++)
    if (s[i] == '0')
      n0++;
    else
      n1++;
  long long res = c0 * n0 + c1 * n1;
  res = min(res, n1 * h + c0 * n);
  res = min(res, n0 * h + c1 * n);
  cout << res;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t;
  cin >> t;
  for (long long i = 1; i <= t; i++) {
    solve();
    cout << "\n";
  }
}
