#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 5;
long long arr[N + 5];
signed main() {
  long long t;
  cin >> t;
  while (t--) {
    long long n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    long long ans = 0;
    for (long long i = 0; i < s.length(); i++) {
      if (s[i] == '0') {
        ans += min(c0, h + c1);
      } else {
        ans += min(c1, h + c0);
      }
    }
    cout << ans << endl;
  }
  return 0;
}
