#include <bits/stdc++.h>
using namespace std;
int t, n, c0, c1, h, cnt0, cnt1, ans;
string s;
int main() {
  cin >> t;
  while (t--) {
    cnt0 = 0, cnt1 = 0, ans = 0;
    cin >> n >> c0 >> c1 >> h >> s;
    for (int i = 0; i < n; i++) {
      if (s[i] == '0') {
        cnt0++;
      } else {
        cnt1++;
      }
    }
    if (h >= abs(c0 - c1)) {
      ans = cnt0 * c0 + cnt1 * c1;
    } else if (c0 > c1) {
      ans = cnt0 * h + n * c1;
    } else {
      ans = cnt1 * h + n * c0;
    }
    cout << ans << endl;
  }
  return 0;
}
