#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, c0, c1, p;
    cin >> n >> c0 >> c1 >> p;
    string s;
    cin >> s;
    int cnt1 = 0, cnt2 = 0;
    for (int i = 0; i < n; i++) {
      if (s[i] == '0')
        cnt2++;
      else
        cnt1++;
    }
    int ans1 = 0, ans2 = 0;
    ans1 = c1 * n + p * cnt2;
    ans2 = c0 * n + p * cnt1;
    int ans3 = c0 * cnt2 + c1 * cnt1;
    if (ans1 <= ans2 && ans1 <= ans3)
      cout << ans1 << endl;
    else if (ans2 <= ans1 && ans2 <= ans3)
      cout << ans2 << endl;
    else
      cout << ans3 << endl;
  }
}
