#include <bits/stdc++.h>
using namespace std;
void A() {
  long long int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  int ones = 0, zeros = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == '1') {
      ones++;
    } else {
      zeros++;
    }
  }
  long long int oneCost = min(h + c0, c1);
  long long int zeroCost = min(h + c1, c0);
  cout << (ones * oneCost) + (zeros * zeroCost) << endl;
  return;
}
int main() {
  int test;
  cin >> test;
  while (test--) {
    A();
  }
  return 0;
}
