#include <bits/stdc++.h>
using namespace std;
long long a, b, c, n, m, k, x, y, z, cnt, ans, tt;
string s;
vector<long long> v, q, t;
int main() {
  long long c0, c1, h;
  cin >> tt;
  while (tt--) {
    cin >> n >> c0 >> c1 >> h >> s;
    cnt = 0;
    ans = 0;
    for (long long i = 0; i < s.size(); i++) {
      if (s[i] == '1')
        cnt++;
      else
        ans++;
    }
    if (c0 == c1)
      cout << c0 * n << "\n";
    else if (c0 + h < c1)
      cout << c0 * n + (cnt * h) << "\n";
    else if (c1 + h < c0)
      cout << (c1 * n) + (ans * h) << "\n";
    else
      cout << (c1 * cnt) + (c0 * ans) << "\n";
  }
}
