#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pp = pair<ll, int>;
const ll mod = 998244353;
const int mxx = 1000000;
ll binpow(ll a, ll n) {
  ll res = 1;
  while (n) {
    if (n & 1) res = (res * a) % mod;
    a = (a * a) % mod;
    n >>= 1;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n, c0, c1, h;
    cin >> n >> c0 >> c1 >> h;
    string s;
    cin >> s;
    int res = 0;
    for (auto el : s) {
      if (el == '0') {
        res += min(c0, h + c1);
      } else {
        res += min(c1, h + c0);
      }
    }
    cout << res << endl;
  }
  return 0;
}
