#include <bits/stdc++.h>
using namespace std;
const long long mod = 1003, INF = 2e18;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t = 1;
  cin >> t;
  while (t--) {
    long long n, c0, c1, h, ans = INF, count1 = 0;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    for (int i = 0; i < n; i++)
      if (s[i] == '0') {
        count1++;
      }
    ans = min(ans, h * count1 + c1 * n);
    ans = min(ans, h * (n - count1) + c0 * n);
    ans = min(ans, c0 * count1 + (n - count1) * c1);
    cout << ans << "\n";
  }
  return 0;
}
