#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int x, test;
  cin >> test;
  while (test--) {
    int n, c0, c1, h;
    string s;
    cin >> n >> c0 >> c1 >> h >> s;
    int cnt0 = 0, cnt1 = 0;
    for (auto &z : s) {
      cnt0 += z == '0';
      cnt1 += z == '1';
    }
    int cost = (cnt0 * c0) + (cnt1 * c1);
    int cost0 = (c0 * n) + (cnt1 * h);
    int cost1 = (c1 * n) + (cnt0 * h);
    cout << min({cost, cost0, cost1}) << '\n';
  }
  return 0;
}
