#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t;
  cin >> t;
  while (t--) {
    long long int n, i, c0, c1, cnt = 0, cnt1 = 0, sum = 0, sum1 = 0, sum2 = 0,
                                h;
    string s;
    vector<long long int> v;
    cin >> n >> c0 >> c1 >> h >> s;
    for (i = 0; i < n; i++) {
      if (s[i] == '0')
        cnt++;
      else
        cnt1++;
    }
    sum = cnt * h + n * c1;
    sum1 = cnt1 * h + n * c0;
    sum2 = cnt * c0 + cnt1 * c1;
    sum = min(sum, min(sum2, sum1));
    cout << sum << endl;
  }
  return 0;
}
