#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n, c0, c1, h;
  string s;
  cin >> n >> c0 >> c1 >> h;
  cin >> s;
  int change = 0;
  int cnt0 = 0;
  int cnt1 = 0;
  int size = s.length();
  if (c0 == c1) {
    cout << n * c1 << endl;
  } else {
    for (int i = 0; i < size; i++) {
      if (s[i] == '0') {
        cnt0++;
      }
    }
    for (int i = 0; i < size; i++) {
      if (s[i] == '1') {
        cnt1++;
      }
    }
    if (h >= c0 && h >= c1) {
      cout << cnt0 * c0 + cnt1 * c1 << endl;
    } else if (h + min(c0, c1) >= max(c0, c1)) {
      cout << cnt0 * c0 + cnt1 * c1 << endl;
    } else if (h + min(c0, c1) < max(c0, c1)) {
      cout << min((c0 * n) + (cnt1 * h), (c1 * n) + (cnt0 * h)) << endl;
    } else {
      cout << min(c0 * n, c1 * n) << endl;
    }
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
}
