#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 100, OO = 1e9 + 7, T = 50, M = 1e9 + 7, P = 6151, SQ = 280,
          lg = 20;
void solve() {
  int n, c0, c1, t;
  string s;
  cin >> n >> c0 >> c1 >> t >> s;
  int ans = 0;
  for (auto u : s) {
    if (u == '0')
      ans += min(c0, c1 + t);
    else
      ans += min(c1, c0 + t);
  }
  cout << ans << endl;
}
int32_t main() {
  int t;
  cin >> t;
  while (t--) solve();
  return 0;
}
