#include <bits/stdc++.h>
using namespace std;
long long t, n, c0, c1, h;
char s[1005];
int main() {
  scanf("%lld", &t);
  while (t--) {
    scanf("%lld %lld %lld %lld", &n, &c0, &c1, &h);
    scanf("%s", s);
    long long len = strlen(s);
    long long temp1 = 0;
    long long temp2 = 0;
    for (int i = 0; i < len; ++i) {
      if (s[i] == '0')
        temp1++;
      else
        temp2++;
    }
    long long ans1 = temp1 * c0 + temp2 * c1;
    long long ans2 = temp1 * h + len * c1;
    long long ans3 = temp2 * h + len * c0;
    printf("%lld\n", min(ans1, min(ans2, ans3)));
  }
}
