#include <bits/stdc++.h>
using namespace std;
const int N = 75;
const int INF = 1e9;
int passThisCaseToJamesBond() {
  int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string str;
  cin >> str;
  long long ans = 0;
  int count0 = 0, count1 = 0;
  count0 = count(str.begin(), str.end(), '0');
  count1 = count(str.begin(), str.end(), '1');
  if ((c0 <= h) && (c1 <= h) || (c0 == c1)) {
    ans = c0 * count0 + c1 * count1;
  } else {
    if (c0 > c1) {
      ans = min(c1 * count0 + c1 * count1 + h * count0,
                c0 * count0 + c1 * count1);
    } else if (c1 > c0) {
      ans = min(c0 * count0 + c0 * count1 + h * count1,
                c0 * count0 + c1 * count1);
    }
  }
  cout << ans << endl;
  return 0;
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    passThisCaseToJamesBond();
  }
}
