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