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