#include <bits/stdc++.h>
using namespace std;
int n, c0, c1, h;
string s;
void solve() {
  cin >> n >> c0 >> c1 >> h;
  cin >> s;
  int count0 = 0;
  int count1 = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == '0') {
      count0++;
    }
  }
  count1 = n - count0;
  int sum = 0;
  if (c0 > c1 && h < c0) {
    int currsum = c1 * count1 + c0 * count0;
    sum = (count0 * h) + (c1 * n);
    cout << min(sum, currsum) << endl;
    return;
  } else if (c0 < c1 && h < c1) {
    int currsum = c1 * count1 + c0 * count0;
    sum = (count1 * h) + (c0 * n);
    cout << min(sum, currsum) << endl;
    return;
  } else {
    sum += (c0 * count0);
    sum += (c1 * count1);
    cout << sum << endl;
    return;
  }
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}
