#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    int ans = 0;
    int cnt = 0;
    int mini = min(c0, c1);
    for (int i = 0; i < n; i++) {
      if (s[i] == '1') {
        ans += c1;
        if (c1 != mini) cnt++;
      } else {
        ans += c0;
        if (c0 != mini) cnt++;
      }
    }
    ans = min(ans, ((n * mini) + (h * cnt)));
    cout << ans << endl;
  }
}
