#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  int ans = 0;
  for (char ch : s) {
    if (ch == '0') {
      ans += min(c0, c1 + h);
    } else {
      ans += min(c1, c0 + h);
    }
  }
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int tc = 1;
  cin >> tc;
  while (tc--) {
    solve();
  }
  return 0;
}
