#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  long long cnt0 = 0, cnt1 = 0;
  for (long long i = 0; i < n; i++) {
    if (s[i] == '0')
      cnt0++;
    else
      cnt1++;
  }
  cout << min({cnt0 * c0 + cnt1 * c1, cnt0 * (c1 + h) + cnt1 * c1,
               cnt0 * c0 + cnt1 * (h + c0)})
       << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed;
  cout.precision(30);
  long long t = 1;
  cin >> t;
  while (t--) solve();
}
