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