#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, c0, c1, h, min, sum = 0;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  vector<long long int> v(n);
  for (long long int i = 0; i < n; i++) {
    if (s[i] == '0')
      v[i] = c0;
    else
      v[i] = c1;
  }
  if (c0 < c1)
    min = c0;
  else
    min = c1;
  for (long long int i = 0; i < n; i++) {
    if (v[i] != min && v[i] > (min + h)) v[i] = min + h;
    sum = sum + (v[i]);
  }
  cout << sum << endl;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int t;
  cin >> t;
  while (t--) solve();
  return 0;
}
